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PYRO1.TXT Preparation of Contact Explosives
This is part of a series of files on pyrotechnics and explosives. It's serious
stuff, and can be really dangerous if you don't treat it seriously. For you
kids out there who watch too many cartoons, remember that if a part of your
body gets blown away in the REAL world, it STAYS blown away. If you can't
treat this stuff with respect, don't screw around with it.
Each file will start with a set of safety rules. Don't skip over them. Read
'em and MEMORIZE 'em!! At the beginning, there will be a set of general rules
that always apply. Then there will be some things that you HAVE TO KNOW about
the materials you will be using and making this time. Read it thoroughly
before starting anything.
Pyrotechnic preparations and explosives are, by their very nature, unstable,
and subject to ignition by explosion or heat, shock, or friction. A clear
understanding of their dangerous properties and due care in the handling of
ingredients or finished products is necessary if accidents are to be avoided.
Always observe all possible precautions, particularly the following:
1. Mix only small batches at one time. This means a few grams, or at
most, an ounce or so. Don't go for big mixes -- they only make for
bigger accidents. The power of an explosive cubes itself with
every ounce. (9 Ounces is 729 times as powerful as one ounce.)
2. When weighing chemicals, use a clean piece of paper on the scale
pan for each item. Then discard the used paper into a bucket of
water before weighing the next ingredient.
3. Be a safe worker. Dispose of any chemicals spilled on the
workbench or equipment between weighings. Don't keep open
containers of chemicals on your table, since accidental spillage
or mixing may occur. When finished with a container, close it, and
replace it on the storage shelf. Use only clean equipment.
4. Where chemicals are to be ground, grind them separately, NEVER
TOGETHER. Thoroughly wash and clean equipment before grinding
another ingredient.
5. Mixing of batches should be done outdoors, away from flammable
structures, such as buildings, barns, garages, etc. Mixes should
also be made in NON METALLIC containers to avoid sparks. Glass
also should not be used since it will shatter in case of an
accident. Handy small containers can be made by cutting off the
top of a plastic bottle three or four inches from the bottom. Some
mixes may most conveniently be made by placing the ingredients in
a plastic bottle and rolling around until the mixture is uniform.
In all cases, point the open end of the container away from
yourself. Never hold your body or face over the container. Any
stirring should be done with a wooden paddle or stick to avoid
sparks or static.
Powdered or ground materials may also be mixed by placing them on
a large sheet of paper on a flat surface and then rolling them
across the sheet by lifting the sides and corners one at a time.
6. Never ram or tamp mixes into paper or cardboard tubes. Pour the
material in and gently tap or shake the tube to settle the
contents down.
7. Store ingredients and finished mixes where they will not be a fire
hazard away from heat and flame. Finished preparations may be
stored in plastic bottles which will not shatter in case of an
accident. Since many of the ingredients and mixes are poisonous,
they should be stored out of reach of children or pets, preferably
locked away.
8. Be sure threads of screw top containers and caps are thoroughly
cleaned. This applies also to containers with stoppers of rubber
or cork and to all other types of closures. Traces of mixture
caught between the container and closure may be ignited by the
friction of opening or closing the container. Throughout any
procedure, WORK WITH CLEAN CONDITIONS.
9. ALWAYS WEAR A FACE SHIELD OR AT LEAST SHATTERPROOF SAFETY GLASSES.
Any careful worker does when handling dangerous materials. Be sure
lenses and frames are not flammable.
10. Always wear a dust respirator when handling chemicals in dust
form. These small particles gather in your lungs and stay there.
They may cause serious illnesses later on in life.
11. Always wear gloves when working with chemicals.
12. Always wear a waterproof lab apron.
13. If you must work indoors, have a good ventilation system.
14. Never smoke anywhere near where you are working.
15. Make sure there are NO open flames present, and NO MOTORS (they
produce sparks inside.) No hot water heaters, furnaces, or pilot
lights in stoves!! Sparks have been known to very readily explode
dust floating in the air.
16. ALWAYS work with someone. Two heads are better than one.
17. Have a source of water READILY available. (Fire extinguisher,
hose, etc.)
18. Never, under any circumstances, use any metal to load chemicals or
put chemicals in. Fireworks with metal casings are worse to handle
than a live hand grenade. Never use any metal container or can.
This includes the very dangerous CO2 cartridges. Many people have
been KILLED because of flying fragments from metal casings. Again,
please do not use metal in any circumstance.
19. Always be thoroughly familiar with the chemicals you are using.
Some information will be included in each file, but look for
whatever extra information you can. Materials that were once
thought to be safe can later be found out to be dangerous stuff.
20. Wash your hands and face thoroughly after using chemicals. Don't
forget to wash your EARS AND YOUR NOSE.
21. If any device you've built fails to work, leave it alone. After a
half hour or so, you may try to bury it, but never try to unload
or reuse any dud.
22. If dust particles start to form in the air, stop what you are
doing and leave until it settles.
23. Read the entire file before trying to do anything.
24. NEVER strike any mixture containing Chlorates, Nitrates,
Perchlorates, Permanganates, Bichromates, or powdered metals don't
drop them, or even handle them roughly.
These rules may all look like a lot of silly nonsense, but let's look at one
example. When the move "The Wizard of OZ" was made, the actress who played the
good witch was severely burned when one of the exploding special effects got
out of hand. The actress who played the bad witch got really messed up by the
green coloring used on her face, and the original actor who played the Tin Man
got his lungs destroyed by the aluminum dust used to color his face. The actor
we know of as the tin man was actually a replacement. The point is, these
chemicals were being used under the direction of people a lot more knowlegable
of chemicals than you are, and terrible accidents still happened. Don't take
this stuff lightly.
The contact explosives we will be describing use only a few chemicals. Some do
need extra caution to keep from causing trouble.
Iodine Crystals
Though most people don't realize it, Iodine is not a brown liquid, but a
steel-grey solid. The tincture of iodine you buy at the drugstore actually
contains just a tiny bit of iodine dissolved in a jarful of inexpensive
alcohol, and resold at a huge mark up. We'll be using iodine in the crystalline
form. On contact with your skin, it will produce a dark stain that won't wash
off with soap and water. We'll talk about removing these stains later. If it
gets hot, it vaporizes into a purple cloud, that smells like the chlorine in a
swimming pool. This cloud is dangerous to inhale, since it will condense in
your lungs, and is corrosive. Since we won't need to heat this stuff, it is not
a problem, but you should make sure that you don't let any iodine crystals
spill onto a hot surface. If you don't touch it and keep it away from your
face, you shouldn't have any troubles.
Ammonium Hydroxide
This is just good old household ammonia. Be sure to get the clear kind. The
sudsy stuff won't be too useful. It is made from ammonia gas dissolved in
water, and every time you open the bottle, it loses some of its strength, so be
sure to use fresh stuff. We need it to be as strong as possible. Some of the
formulas given here use lab grade concentrated ammonium hydroxide. It is much
stronger than the supermarket kind, and is very unkind to skin or especially
the eyes. It is a good idea to wear eye protection with even the supermarket
grade. Though we don't usually worry about this when using household ammonia
for cleaning, we usually dilute it for that. Here we'll be using it straight
out of the bottle, and it is much more corrosive in that form. Never use this
material if you don't have real good ventilation, as the ammonia vapors can be
overpowering.
Potassium Iodide
This is a reasonably safe chemical. You get Potassium ions in some of the fruit
you eat, and Iodide ions (usually as Sodium Iodide) are added to the table salt
you buy at the store. So, while you don't directly eat this chemical, you do
eat the components that make it up. Don't be scared of this stuff.
Sodium Thiosulfate
Otherwise known as photographic hypo. When dissolved in water, this will remove
the iodine stains left by touching iodine crystals, and exploding contact
explosive. Not particularly nasty stuff, but make sure to wash it off after
cleaning yourself with it.
General Information
This is a powerful and highly sensitive explosive. A dust sized particle will
make a sharp crack or popping sound. A piece the size of a pencil lead will
produce an explosion as loud as any of the largest firecrackers or cherry
bombs. It cannot be exploded by any means when wet, and therefore can be
handled and applied with safety. When dry, it will explode with the touch of a
feather, or a breath of air.
The strength of the ammonia water you use will have a direct effect on the
strength of the final product. If you use supermarket ammonia, the explosive
will work, but not as spectacularly as if you use a 15% or higher (10 to 15
molar) solution. The stronger it is, the better. You'll also need filter paper,
and a funnel. A properly folded coffee filter will do nicely if you don't have
the filter paper. If you're not sure how to fold filter paper, check an
elementary chemistry textbook.
Methods of Preparation
1.) Granular Explosive. This is the easiest kind, and the only kind that will
work reasonably well with supermarket ammonia. Crush enough iodine crystals to
make a pile of powder equal to the volume of a pencil eraser. Do not grind into
a fine powder. Put about 4 ounces or 1/2 measuring cup of strong ammonia water
into a small container with the iodine, and seal it for about 5 to 10 minutes,
shaking frequently. While the mixture is reacting, get your filter paper ready.
While it is best to consult a book that shows how to do this, you take the
circle of filter paper, fold it in half, fold it again at right angles to the
first fold, and then open it to form a cone. Open or close it as needed to make
it conform to the angle of the funnel, and moisten it a little to make it stick
in place. Place the funnel over a container that will catch the waste liquid.
Let the mixture settle long enough for the sediment to settle, and pour off as
much of the clear liquid as possible before filtering the sediment. Pour the
remaining liquid and sediment into the filter. The sediment (and the filter
paper covered with it!!!) is your explosive. The small amount you have made
will go a lot farther than you realize. Particularly if you used good strong
ammonia. Place the explosive in an airtight leakproof pill bottle. As this
explosive is unstable by nature, fresh amounts give better results than stale
ones that have been sitting around for a day or so. Best results are obtained
with small fresh batches. But as you'll see, there are a few tricks you can do
with this material that do require it to sit for a day or more.
The explosive should be stored and applied while wet.
2.) Paint type explosive. This will use up a lot of iodine crystals. Make up a
strong tincture of iodine using about 4 ounces or 1/2 measuring cup of rubbing
alcohol, denatured alcohol, or wood alcohol. Wood alcohol is preferable. Add
iodine crystals and shake thoroughly until no more will dissolve. Pour the
liquid into a fruit jar. Add the ammonium hydroxide and stir the mixture until
the mixture is a chocolate brown and shows a little of the original color of
the iodine. The amount of ammonia necessary will depend on its strength. An
equal volume of ammonia is usually sufficient for a 15% or higher solution. The
solution should be filtered at once, and shouldn't ever wait more than 10 or 15
minutes, because it starts to dissolve again.
The explosive again should be stored and applied while wet. This material is
chemically the same as the granular explosive, but because it was precipitated
from a solution, it is much more finely divided, and the reaction happens
almost simultaneously, so you can get it out before it all vanishes back into
the solution.
3.) Paint type #2. Dissolve 1 gram of potassium iodide in about 90cc of
18%-22% ammonium hydroxide. Add 4 grams of pulverized iodine. A deep black
sediment should start forming. Let stand, and stir frequently for five minutes.
Then, filter as usual. While the potassium iodide is not an integral part of
the chemical reaction, the dissolved potassium iodide will allow the iodine
crystals in turn to dissolve, and its common ion effect will cause less iodine
crystals to be wasted. Since the iodine is by far the most expensive
ingredient, you'll save money in the long run by using it.
Care in Handling And Storage
Because this material is so unstable it deteriorates quickly. Don't make any
more than you need to use in the next 24 hours. If you can't use it all
immediately, the container you keep it in should be recapped tightly after use
and the mouth wiped clean. The explosive can cause dark stain damage to things
as rugs, clothing, chair seats, wallpaper, and light or clear plastics. A
strong solution of sodium thiosulfate is effective for removing stains from
hands and clothing before they set. Never leave the container of explosive in
direct sunlight for more than a few minutes, as it will weaken the strength. Do
NOT attempt to make a large explosion as it is dangerous and can cause
deafness. All equipment used should be thoroughly washed and the used filter
paper flushed down the toilet. Under no circumstances attempt to handle the
dried material which is extremely explosive and hazardous. If you can avoid
storing the material in a container at all, there will be no chance that a
loose stopper will let the material dry out and become a potential bomb. Tiny
bits of this can be great fun, but it has to be handled with care.
Application
Although largely a scientific curiosity, this explosive finds itself well
suited for practical jokes. It may easily be painted on the bottom side of
light switches, sprinkled on floors, painted in keyholes, pencil sharpeners,
doorknobs and in hundreds of other unsuspected places. It is also ideal for
catching locker thieves and desk prowlers. It will leave a dark stain on his
hands when it explodes, and only you will know how to remove it.
Reaction Equations
Ammonium
Ammonium Ammonium Nitrogen
Iodine Hydroxide Iodide Tri Iodide Water
3I + 5NH OH ---> 3NH I + NH NI + 5H O
2 4 4 3 3 2
The theoretical yield of explosive from pure iodine is 54.1% by weight. The
remainder of the iodine may be recovered for reuse from the ammonium iodide
waste product by evaporating the waste liquid and treating with chlorine if a
chemistry lab is available. The contact explosive is Ammonium Nitrogen
Tri-Iodide, which explodes into iodine, nitrogen, and ammonia.
Ammonium
Nitrigen
Tri-Iodide Iodine Nitrogen Ammonia
2NH NI ---> 3I + N + 2NH
3 3 2 2 3
Some Clever Uses For This Material
1.) Contact Explosive Torpedos. Get some gelatin capsules, the kind pills are
made of. Fill the small half with uncooked dry tapioca until it is half full.
Then place a wet blob of contact explosive about 4 times the size of a straight
pin head on top of it. Either the granular or paint type explosive will work.
The capsule is then filled the rest of the way up with tapioca until, when the
capsule is put together, the grains of tapioca are packed tightly, and none are
loose. If this is not done properly, the torpedos could go off prematurely, and
the joke would be on you. The torpedos are then moistened at the joints to seal
them and stored until the next day. They are not sensitive enough until the
next day and too sensitive the day after, so plan your activities accordingly.
These torpedos are the most fiendish devices made. You can lay one on top of a
door, where it will roll off when the door is opened, and it will explode on
contact with the floor. If you toss one some distance away it will appear as if
someone else was responsible for the explosion. These torpedos are ideal as
booby traps or for pulling practical jokes with. They may be carried in a small
box filled with cotton until needed. Just treat the box gently, and all will be
well.
2.Contact Explosive Booby Traps. Prepare a small amount of contact explosive.
Cut strips of newspaper 1 1/2 inches wide and 1 foot long. Cut a piece of
string 1 foot long. Put a small amount of wet contact explosive on the strip of
paper 1 inch from the end. Double the string. Now pull one end of the string
back until there is a double loop in the string about 1 inch long. Do not tie.
Lay this double loop across the wet contact explosive and tightly roll the
paper and glue the end. Put away for a few days until thoroughly dry. When dry,
pull the ends of the string and the booby trap will explode. The strings, when
pulled, rub against the dry contact explosive, and make it explode.
Getting The Materials
There are quite a few chemical supply houses that you can mail order the
materials you need. You'll have to sign a form stating that you're over 21 and
won't use the chemicals for the types of things we're learning here. Note that
the people who run these supply houses know what Iodine Crystals and Ammonium
Hydroxide can do when mixed together, and if you order both from the same
place, or in the same order, it may arouse some suspicion.
Check the classified ads in the back of magazines like Popular Science for the
current supply houses. Order as many catalogs as you can find. Not all sell
every chemical that you may want for this series. Also, you can break the
orders up so as not to look suspicious. Lastly, some houses are used to selling
to individuals, and will provide chemicals in 1 or 4 ounce lots, while others
prefer to sell to large institutions, and sell their wares in 1 or 5 pound
jugs. Split up your orders according to the quantities of each item you think
you will be needing. An ounce of Iodine Crystals will cost three or four
dollars an ounce, and an ounce bottle of iodine is pretty tiny, but it goes a
long way. If you had to buy that by the pound, you might just want to forget
the whole thing.
PYRO2.TXT Touch Paper, Self Igniting Mixtures, Percussion Explosives
This is part of a series of files on pyrotechnics and explosives. It's serious
stuff, and can be really dangerous if you don't treat it seriously. For you
kids out there who watch too many cartoons, remember that if a part of your
body gets blown away in the REAL world, it STAYS blown away. If you can't
treat this stuff with respect, don't screw around with it.
Each file will start with a set of safety rules. Don't skip over them. Read
'em and MEMORIZE 'em!! At the beginning, there will be a set of general rules
that always apply. Then there will be some things that you HAVE TO KNOW about
the materials you will be using and making this time. Read it thoroughly
before starting anything.
Pyrotechnic preparations and explosives are, by their very nature, unstable,
and subject to ignition by explosion or heat, shock, or friction. A clear
understanding of their dangerous properties and due care in the handling of
ingredients or finished products is necessary if accidents are to be avoided.
Always observe all possible precautions, particularly the following:
1. Mix only small batches at one time. This means a few grams, or at
most, an ounce or so. Don't go for big mixes -- they only make for
bigger accidents. The power of an explosive cubes itself with
every ounce. (9 Ounces is 729 times as powerful as one ounce.)
2. When weighing chemicals, use a clean piece of paper on the scale
pan for each item. Then discard the used paper into a bucket of
water before weighing the next ingredient.
3. Be a safe worker. Dispose of any chemicals spilled on the
workbench or equipment between weighings. Don't keep open
containers of chemicals on your table, since accidental spillage
or mixing may occur. When finished with a container, close it, and
replace it on the storage shelf. Use only clean equipment.
4. Where chemicals are to be ground, grind them separately, NEVER
TOGETHER. Thoroughly wash and clean equipment before grinding
another ingredient.
5. Mixing of batches should be done outdoors, away from flammable
structures, such as buildings, barns, garages, etc. Mixes should
also be made in NON METALLIC containers to avoid sparks. Glass
also should not be used since it will shatter in case of an
accident. Handy small containers can be made by cutting off the
top of a plastic bottle three or four inches from the bottom. Some
mixes may most conveniently be made by placing the ingredients in
a plastic bottle and rolling around until the mixture is uniform.
In all cases, point the open end of the container away from
yourself. Never hold your body or face over the container. Any
stirring should be done with a wooden paddle or stick to avoid
sparks or static.
Powdered or ground materials may also be mixed by placing them on
a large sheet of paper on a flat surface and then rolling them
across the sheet by lifting the sides and corners one at a time.
6. Never ram or tamp mixes into paper or cardboard tubes. Pour the
material in and gently tap or shake the tube to settle the
contents down.
7. Store ingredients and finished mixes where they will not be a fire
hazard away from heat and flame. Finished preparations may be
stored in plastic bottles which will not shatter in case of an
accident. Since many of the ingredients and mixes are poisonous,
they should be stored out of reach of children or pets, preferably
locked away.
8. Be sure threads of screw top containers and caps are thoroughly
cleaned. This applies also to containers with stoppers of rubber
or cork and to all other types of closures. Traces of mixture
caught between the container and closure may be ignited by the
friction of opening or closing the container. Throughout any
procedure, WORK WITH CLEAN CONDITIONS.
9. ALWAYS WEAR A FACE SHIELD OR AT LEAST SHATTERPROOF SAFETY GLASSES.
Any careful worker does when handling dangerous materials. Be sure
lenses and frames are not flammable.
10. Always wear a dust respirator when handling chemicals in dust
form. These small particles gather in your lungs and stay there.
They may cause serious illnesses later on in life.
11. Always wear gloves when working with chemicals.
12. Always wear a waterproof lab apron.
13. If you must work indoors, have a good ventilation system.
14. Never smoke anywhere near where you are working.
15. Make sure there are NO open flames present, and NO MOTORS (they
produce sparks inside.) No hot water heaters, furnaces, or pilot
lights in stoves!! Sparks have been known to very readily explode
dust floating in the air.
16. ALWAYS work with someone. Two heads are better than one.
17. Have a source of water READILY available. (Fire extinguisher,
hose, etc.)
18. Never, under any circumstances, use any metal to load chemicals or
put chemicals in. Fireworks with metal casings are worse to handle
than a live hand grenade. Never use any metal container or can.
This includes the very dangerous CO2 cartridges. Many people have
been KILLED because of flying fragments from metal casings. Again,
please do not use metal in any circumstance.
19. Always be thoroughly familiar with the chemicals you are using.
Some information will be included in each file, but look for
whatever extra information you can. Materials that were once
thought to be safe can later be found out to be dangerous stuff.
20. Wash your hands and face thoroughly after using chemicals. Don't
forget to wash your EARS AND YOUR NOSE.
21. If any device you've built fails to work, leave it alone. After a
half hour or so, you may try to bury it, but never try to unload
or reuse any dud.
22. If dust particles start to form in the air, stop what you are
doing and leave until it settles.
23. Read the entire file before trying to do anything.
24. NEVER strike any mixture containing Chlorates, Nitrates,
Perchlorates, Permanganates, Bichromates, or powdered metals don't
drop them, or even handle them roughly.
These rules may all look like a lot of silly nonsense, but let's look at one
example. When the move "The Wizard of OZ" was made, the actress who played the
good witch was severely burned when one of the exploding special effects got
out of hand. The actress who played the bad witch got really messed up by the
green coloring used on her face, and the original actor who played the Tin Man
got his lungs destroyed by the aluminum dust used to color his face. The actor
we know of as the tin man was actually a replacement. The point is, these
chemicals were being used under the direction of people a lot more knowlegable
of chemicals than you are, and terrible accidents still happened. Don't take
this stuff lightly.
We will be using many more chemicals this time, and some can be quite
dangerous. Please read the following information carefully.
Sodium Azide - NaN
3
This white powder is very poisonous. It is also a bit unstable, so treat it
gently.
Lead Nitrate - Pb(NO )
3 2
This contains poisonous lead and is very water soluble so your body will
absorb it quickly, given the chance. The government has banned leaded paints
and is phasing out leaded gasoline because the stuff slowly accumulates in
your body and can screw up all sorts of important innards. If you are careless
with Lead Nitrate you can do a few lifetimes' worth of damage in one
afternoon.
Ammonium Nitrate - NH NO
4 3
Commonly used as fertilizer, this stuff is somewhat dangerous in large
quantities, particularly if it gets very hot. (Entire shiploads of this
material have been known to go up all at once.) When heated gently, it
decomposes into water and nitrous oxide (laughing gas). Farmers sometimes use
it to blow up tree stumps by mixing it with fuel oil and setting the gunk off
with a detonator. We'll have a very different use for it here.
Potassium Nitrate - KNO
3
Also known as saltpeter, this is commercially used as a diuretic for animals.
It also works as an oxidizing agent in various pyrotechnic mixtures. That is,
when heated it provides the oxygen needed to make the rest of the mixture
burn.
Potassium Potassium
Nitrate Nitrite Oxygen
2KNO ---> 2KNO + O
3 2 2
Potassium Chlorate - KClO
3
A much more spectacular oxidizing agent than Potassium Nitrate. It not only
yields more oxygen than Potassium Nitrate, it does so more easily. Pyrotechnic
mixtures containing this chemical will require much less of it, and yet burn
more fiercely. Even percussion can readily set the mixtures off. This can be
useful, but it sometimes makes the mixtures more sensitive than you'd like.
Mixtures containing this chemical must be handled carefully. Potassium
Chlorate is also poisonous.
Potassium Potassium
Chlorate Chloride Oxygen
2KClO ---> 2KCl + 3O
3 2
Aluminum Dust
Very finely divided aluminum. When put in a glass jar, it almost looks like a
solid piece of grey metal. In this form it is flammable. Also, it can
seriously damage your lungs if you inhale it. Be careful not to stir up any
clouds of dust, and it goes without saying that you shouldn't use it near an
open flame.
Zinc Dust
Very finely divided zinc. Not quite as flammable as Aluminum Dust, but still
worth handling carefully. Can also damage your lungs if inhaled.
Lampblack
This is very finely divided carbon, usually obtained as a soot from other
manufacturing processes. It is much more effective in pyrotechnic mixtures
than powdered charcoal. Tiny spots of this are almost unnoticeable, but they
stick to your hands and smear incredibly far. If you're not very tidy you
should expect to find black smears all over your face and hands after using
this.
Sulfur
A yellow powder used as a reducing agent in many pyrotechnic mixtures. Buy
this in the finely powdered form. You can also get it in hard lumps, but these
will just waste extra time as you have to grind them yourself.
Potassium Permanganate
An oxidizing agent that's somewhat less vigorous than others mentioned here.
Not usually used in pyrotechnic mixtures because it's more expensive and less
effective than some of the alternatives. There are a few cases when it's just
the right thing. Don't let this accidentally come in contact with glycerine.
If such an accident happens, the resulting mess should be immediately wiped up
with wet paper towels and buried or flushed down a toilet. It should NOT be
thrown away in a dry waste receptacle!!!
Gum Arabic
A white powder which is mixed with water to make a glue like substance. Useful
for coating various mixtures or binding them together into a solid mass.
Sodium Peroxide
A very strange and dangerous oxidizer. Don't let it get wet and don't let it
touch your skin.
Glycerine
A thick liquid, chemically similar to rubbing alcohol. Though harder to get
burning, it will burn in the right circumstances. Fairly safe stuff.
Iodine Crystals
Pure Iodine is a steel grey solid, which is poisonous and which produses
poisonous vapors when heated. Smells similar to the chlorine used in bleaches
and swimming pools. If you accidentally should drop some on a hot surface and
notice the odor, you should leave the area.
Touch Paper
This is an easily made material that acts like a slow burning fuse and is
ideal for testing small amounts of a pyrotechnic mixture. It is made by
soaking a piece of absorbent paper, like a paper towel, in a saturated
solution of Potassium Nitrate. (A saturated solution means that you have
dissolved as much of the chemical in water as is possible.) Hang the paper up
to dry, and be sure to wipe up any drips. When dry it is ready. Cut off a
small strip and light the edge to see how different it acts from ordinary
paper. This will ignite all but the most stubborn mixtures, and will ignite
gunpowder, which will in turn ignite most anything else.
Don't dip the towel in the Potassium Nitrate solution a second time to try to
make it "stronger". This will actually make it less effective. Some of the
fancier paper towels don't work too well for this. Best results are obtained
from the cheap folded paper towels found in public restrooms everywhere.
Self Igniting Mixtures
Pulverize 1 gram of Potassium Permanganate crystals and place them on an
asbestos board or in an earthenware vessel. Let 2-3 drops of glycerine fall
onto the Potassium Permanganate. The mixture will eventually sizzle and then
flare. Potassium Permanganate is the oxidizing agent. The glycerine is
oxidized so quickly that heat is generated faster than it can be dissipated.
Consequently, the glycerine is ignited. Because this mixture takes so long to
catch on fire, it is sometimes useful when a time delay is needed to set off
some other mixture. If you lose patience with this test, DO NOT THROW THE
MIXTURE AWAY IN A WASTEBASKET!!! Either bury it or flush it down a toilet. I
know of at least one house fire that was started because this was not done.
Given time, this stuff WILL start to burn.
This demonstration produces a very nice effect, but sends out a lot of
poisonous fumes, so do it outside. Make a mound of equal volumes of iodine
crystals and aluminum dust. Make a small indentation at the top of the mound
and add a drop or two of water and move away. It will hiss and burst into
flame, generating thick purple smoke. The fumes are Iodine vapor which is
very caustic, so make sure you are upwind of the fire. Since this is set off
by moisture, you should not store the mixed material. Mix it immediately
before you plan to use it.
Shred a small piece of newspaper and place on it a small amount of sodium
peroxide. Add two drops of hot water. The paper will be ignited. CAUTION: Keep
Sodium Peroxide from moisture and out of contact with organic materials (your
skin, for example.)
Ammonium Nitrate, 5 grams, 1 gram of Ammonium Chloride. Grind these
SEPARATELY, and add 1/4 gram of zinc dust. Form a cone and add 2-4 drops of
water. A bright blue flame with large volumes of smoke forms. Depending on the
quality of your zinc dust, you may need to increase the quantity of zinc.
Since this is ignited by moisture, you should not attempt to store this
mixture.
Percussion Explosives
This section will not only introduce a couple of mixtures with interesting
possibilities, but it will also demonstrate how sensitive mixtures containing
Potassium Chlorate can be. Keep in mind that Chlorate mixtures can be a LOT
more sensitive than the ones shown here.
Mix 1 part by weight of Sulfur, and 3 parts Potassium Chlorate. Each should be
ground separately in a mortar. They should be mixed lightly without any
pressure on a sheet of paper. A small amount of this mixture (less than one
gram!!) placed on a hard surface and struck with a hammer will explode with a
loud report.
Mix the following parts by weight, the same way as above,
Potassium Chlorate 6
Lampblack 4
Sulfur 1
Both of these mixtures are flammable. Mix small quantities only.
Lead Azide Pb(N )
3 2
Unlike many explosives that must be enclosed in a casing to explode, and
others that require a detonator to set them off, Lead Azide will explode in
open air, either due to heat or percussion. Mixed with gum arabic glue, tiny
dots of it are placed under match heads to make trick exploding matches. The
same mixture coated onto 1/2 " wood splinters are used to "load" cigars. In
larger amounts, it is used as a detonator. A moderately light tap will set it
off, making it much more sensitive than the percussion explosives already
mentioned. It is very easy to make.
Take about 1.3 grams of sodium azide and dissolve it in water. It's best not
to use any more water than necessary. In a separate container, dissolve about
3.3 grams of Lead Nitrate, again only using as much water as needed to get it
to dissolve. When the two clear liquids are mixed, a white precipitate of Lead
Azide will settle out of the mixture. Add the Lead Nitrate solution, while
stirring, until no more Lead Azide precipitates out. You may not need to use
it all. Note that the above weights are given only for your convenience if you
have the necessary scales, and give the approximate proportions needed. You
need only continue to mix the solutions until no more precipitate forms.
The precipitate is filtered out and rinsed several times with distilled water.
It is a good idea to store this in its wet form, as it is less sensitive this
way. It's best not to store it if possible, but if you do, you should keep it
in a flexible plastic container that wont produce sharp fragments in case of
an explosion. (NO MORE THAN A GRAM AT A TIME !!!!) Also, make sure that the
mouth of the container is wiped CLEAN before putting the lid on. Just the
shock of removing the lid is enough to set off the dry powder if it is wedged
between the container and the stopper. Don't forget that after you've removed
the precipitate from the filter paper, there will still be enough left to make
the filter paper explosive.
Lead Azide is very powerful as well as very sensitive. Never make more than a
couple of grams at one time.
Reaction Equations
Lead Sodium Lead Sodium
Nitrate Azide Azide Nitrate
Pb(NO ) + 2NaN ---> Pb(N ) + 2NaNO
3 2 3 3 2 3
Don't try to salvage the Sodium Nitrate that's left over (dissolved in the
water). Sodium nitrate is cheap, not really useful for good pyrotechnics, and
this batch will be contaminated with poisonous lead. It's worthless stuff.
Dump it out.
To demonstrate the power of a little bit of Lead Azide, cut out a piece of
touch paper in the following shape
-----------------------------
! !
! !
! ---------------
! !
! ---------------
! !
! !
-----------------------------
Where the size of the wide rectangle is no more than one inch x 1/2 inch, and
the length of the little fuse is at least 3/4 inch. Apply a thin layer of wet
Lead Azide to the large rectangle with a paint brush and let it dry
thoroughly. When done, set this tester out in the open, light the fuse at the
very tip and step back. If done properly, the tiny bit of white powder will
produce a fairly loud explosion.
A Lead Azide Booby Trap
Get some string that's heavy enough so that it won't break when jerked hard. A
couple of feet is enough to test this out. You may want to use a longer piece
depending on what you plan to do with this. Fold a small "Z" shape in the
center of the string, as shown in figure 1. The middle section of the "Z"
should be about one inch long.
-------------------------------------.
.
.
.
--------------------------------------------------
Figure 1. Fold string into a small Z
Next, twist the Z portion together as tightly as you can. Don't worry if it
unwinds a bit when you let go, but it should still stay twisted closely
together. If it doesn't, you will need a different kind of string. Figure 2
tries to show what this will look like.
-------------//////////////////-----------------
Figure 2. Twist the Z portion tightly
Next, apply some wet Lead Azide to the twisted portion with a paint brush. The
Lead Azide should have a bit of Gum Arabic in it to make it sticky. Cut
out a piece of paper, two inches by 6 inches long, wrap it around the twisted
portion, and glue the end on so that it stays put. You should now have a two
inch narrow paper tube with a string sticking out each end, as shown in figure
3.
-------------------------
! !
----------! !-------------------
! !
-------------------------
Figure 3. The completed Booby Trap
You should now set the booby trap aside for at least two weeks so that the
Lead Azide inside can dry completely. Don't try to speed up the process by
heating it. When the two ends of the string are jerked hard, the friction in
the wound up string will set off the Lead Azide. The booby trap can be
attatched to doors, strung out as tripwires, or set up in any other situation
that will cause a quick pull on the strings. Be careful not to use too much
Lead Azide. A little will go a long way. Before trying this on an unsuspecting
soul, make a test booby trap as explained here, tie one end to a long rope,
and set it off from a distance.
The paper wound around the booby trap serves two purposes. It keeps the Lead
Azide from flaking off, and it pads the stuff so it will be less likely to get
set off accidentally. A good vigorous swat will still set it off though, so
store these separately and keep them padded well.
Getting The Chemicals
As always, be sure to use your brains when ordering chemicals from a lab
supply house. Those people KNOW what Sodium Azide and Lead Nitrate make when
mixed together. They also know that someone who orders a bunch of chlorates,
nitrates, metal dusts, sulfur, and the like, probably has mischeif in mind,
and they keep records. So break your orders up, order from different supply
houses, get some friends to order some of the materials, and try to order the
things long before you plan do do anything with them. It's a pain, and the
multiple orders cost a lot in extra shipping charges, but that's what it costs
to cover your tracks. DO it!
PYRO3.TXT Stars, Flares, and Color Mixtures
This is part of a series of files on pyrotechnics and explosives. It's serious
stuff, and can be really dangerous if you don't treat it seriously. For you
kids out there who watch too many cartoons, remember that if a part of your
body gets blown away in the REAL world, it STAYS blown away. If you can't
treat this stuff with respect, don't screw around with it.
Each file will start with a set of safety rules. Don't skip over them. Read
'em and MEMORIZE 'em!! At the beginning, there will be a set of general rules
that always apply. Then there will be some things that you HAVE TO KNOW about
the materials you will be using and making this time. Read it thoroughly
before starting anything.
Pyrotechnic preparations and explosives are, by their very nature, unstable,
and subject to ignition by explosion or heat, shock, or friction. A clear
understanding of their dangerous properties and due care in the handling of
ingredients or finished products is necessary if accidents are to be avoided.
Always observe all possible precautions, particularly the following:
1. Mix only small batches at one time. This means a few grams, or at
most, an ounce or so. Don't go for big mixes -- they only make for
bigger accidents. The power of an explosive cubes itself with
every ounce. (9 Ounces is 729 times as powerful as one ounce.)
2. When weighing chemicals, use a clean piece of paper on the scale
pan for each item. Then discard the used paper into a bucket of
water before weighing the next ingredient.
3. Be a safe worker. Dispose of any chemicals spilled on the
workbench or equipment between weighings. Don't keep open
containers of chemicals on your table, since accidental spillage
or mixing may occur. When finished with a container, close it, and
replace it on the storage shelf. Use only clean equipment.
4. Where chemicals are to be ground, grind them separately, NEVER
TOGETHER. Thoroughly wash and clean equipment before grinding
another ingredient.
5. Mixing of batches should be done outdoors, away from flammable
structures, such as buildings, barns, garages, etc. Mixes should
also be made in NON METALLIC containers to avoid sparks. Glass
also should not be used since it will shatter in case of an
accident. Handy small containers can be made by cutting off the
top of a plastic bottle three or four inches from the bottom. Some
mixes may most conveniently be made by placing the ingredients in
a plastic bottle and rolling around until the mixture is uniform.
In all cases, point the open end of the container away from
yourself. Never hold your body or face over the container. Any
stirring should be done with a wooden paddle or stick to avoid
sparks or static.
Powdered or ground materials may also be mixed by placing them on
a large sheet of paper on a flat surface and then rolling them
across the sheet by lifting the sides and corners one at a time.
6. Never ram or tamp mixes into paper or cardboard tubes. Pour the
material in and gently tap or shake the tube to settle the
contents down.
7. Store ingredients and finished mixes where they will not be a fire
hazard away from heat and flame. Finished preparations may be
stored in plastic bottles which will not shatter in case of an
accident. Since many of the ingredients and mixes are poisonous,
they should be stored out of reach of children or pets, preferably
locked away.
8. Be sure threads of screw top containers and caps are thoroughly
cleaned. This applies also to containers with stoppers of rubber
or cork and to all other types of closures. Traces of mixture
caught between the container and closure may be ignited by the
friction of opening or closing the container. Throughout any
procedure, WORK WITH CLEAN CONDITIONS.
9. ALWAYS WEAR A FACE SHIELD OR AT LEAST SHATTERPROOF SAFETY GLASSES.
Any careful worker does when handling dangerous materials. Be sure
lenses and frames are not flammable.
10. Always wear a dust respirator when handling chemicals in dust
form. These small particles gather in your lungs and stay there.
They may cause serious illnesses later on in life.
11. Always wear gloves when working with chemicals.
12. Always wear a waterproof lab apron.
13. If you must work indoors, have a good ventilation system.
14. Never smoke anywhere near where you are working.
15. Make sure there are NO open flames present, and NO MOTORS (they
produce sparks inside.) No hot water heaters, furnaces, or pilot
lights in stoves!! Sparks have been known to very readily explode
dust floating in the air.
16. ALWAYS work with someone. Two heads are better than one.
17. Have a source of water READILY available. (Fire extinguisher,
hose, etc.)
18. Never, under any circumstances, use any metal to load chemicals or
put chemicals in. Fireworks with metal casings are worse to handle
than a live hand grenade. Never use any metal container or can.
This includes the very dangerous CO2 cartridges. Many people have
been KILLED because of flying fragments from metal casings. Again,
please do not use metal in any circumstance.
19. Always be thoroughly familiar with the chemicals you are using.
Some information will be included in each file, but look for
whatever extra information you can. Materials that were once
thought to be safe can later be found out to be dangerous stuff.
20. Wash your hands and face thoroughly after using chemicals. Don't
forget to wash your EARS AND YOUR NOSE.
21. If any device you've built fails to work, leave it alone. After a
half hour or so, you may try to bury it, but never try to unload
or reuse any dud.
22. If dust particles start to form in the air, stop what you are
doing and leave until it settles.
23. Read the entire file before trying to do anything.
24. NEVER strike any mixture containing Chlorates, Nitrates,
Perchlorates, Permanganates, Bichromates, or powdered metals don't
drop them, or even handle them roughly.
These rules may all look like a lot of silly nonsense, but let's look at one
example. When the move "The Wizard of OZ" was made, the actress who played the
good witch was severely burned when one of the exploding special effects got
out of hand. The actress who played the bad witch got really messed up by the
green coloring used on her face, and the original actor who played the Tin Man
got his lungs destroyed by the aluminum dust used to color his face. The actor
we know of as the tin man was actually a replacement. The point is, these
chemicals were being used under the direction of people a lot more knowlegable
of chemicals than you are, and terrible accidents still happened. Don't take
this stuff lightly.
We will be using the following materials this time. Get familiar with them.
Some can be highly dangerous.
Aluminum Dust (and powder) Al
An element used for brilliancy in the fine powder form. It can be purchased as
a fine silvery or gray powder. All grades from technical to superpure (99.9%)
can be used. It is dangerous to inhale the dust. The dust is also flammable, by
itself. In coarser forms, like powder, it is less dangerous.
Antimony Sulfide Sb S
2 3
Also known as "Black" Antimony Sulfide. (There is also a "Red" form, which is
useless to us.) This is used to sharpen the report of firecrackers, salutes,
etc, or to add color to a fire. The technical, black, powder is suitable. Avoid
contact with the skin. Dermatitis or worse will be the result.
Barium Chlorate Ba(ClO ) * H O
3 2 2
Available as a white powder. It is poisonous, as are all Barium salts. It is
used both as an oxidizer and color imparter. It is as powerful as Potassium
Chlorate and should be handled with the same care. Melting point is 414
degrees.
Barium Nitrate Ba(NO )
3 2
Poisonous. Used as an oxidizer and colorizer. The uses and precautions are the
same as with a mixture containing Potassium Nitrate.
Charcoal C
A form of the element carbon. Used in fireworks and explosives as a reducing
agent. It can be purchased as a dust on up to a coarse powder. Use dust form,
unless otherwise specified. The softwood variety is best, and it should be
black, not brown.
Copper Acetoarsenite (CuO) As O Cu(C H O )
3 2 3 2 3 2 2
The popular name for this is Paris Green. It is also called King's Green or
Vienna Green. It has been used as an insecticide, and is available as a
technical grade, poisonous, emerald green powder. It is used in fireworks to
add color. Careful with this stuff. It contains arsenic.
Copper Chloride CuCl
2
A color imparter. As with all copper salts, this is poisonous.
Copper Sulfate CuSO *5H O
4 2
Known as Blue Vitriol, this poisonous compound is available as blue crystals or
blue powder. Can be purchased in some drugstores and some agricultural supply
stores. Used as a colorizer.
Dextrine
This can be purchased as a white or yellow powder. It is a good cheap glue for
binding cases and stars in fireworks.
Lampblack C
This is another form of the element carbon. It is a very finely powdered black
dust (soot, actually) resulting from the burning of crude oils. It is used for
special effects in fireworks.
Lead Chloride PbCl
3
Available as a white, crystalline, poisonous powder, which melts at 501
degrees. As with all lead salts, it is not only poisonous, but the poison
accumulates in the body, so a lot of small, otherwise harmless doses can be as
bad as one large dose.
Mercurous Chloride HgCl
Also known as calomel or Mercury Monochloride. This powder will brighten an
otherwise dull colored mixture. Sometimes it is replaced by Hexachlorobenzene
for the same purpose. This is non poisonous ONLY if it is 100% pure. Never
confuse this chemical with Mercuric Chloride, which is poisonous in any purity.
Potassium Chlorate KClO
3
This, perhaps, is the most widely used chemical in fireworks. Before it was
known, mixtures were never spectacular in performance. It opened the door to
what fireworks are today. It is a poisonous, white powder that is used as an
oxidizer. Never ram or strike a mixture containing Potassium Chlorate. Do not
store mixtures containing this chemical for any length of time, as they may
explode spontaneously.
Potassium Dichromate K Cr O
2 2 7
Also known as Potassium Bichromate. The commercial grade is used in fireworks
and matches. The bright orange crystals are poisonous.
Potassium Nitrate KNO
3
Commonly called Saltpeter. This chemical is an oxidizer which decomposes at 400
degrees. It is well known as a component of gunpowder and is also used in other
firework pieces. Available as a white powder.
Potassium Perchlorate KClO
4
Much more stable than its chlorate brother, this chemical is a white or
slightly pink powder. It can often substitute for Potassium Chlorate to make
the mixture safer. It will not yield its oxygen as easily, but to make up for
this, it gives off more oxygen. It is also poisonous.
Red Gum
Rosin similar to shellac and can often replace it in many fireworks formulas.
Red Gum is obtained from barks of trees.
Shellac Powder
An organic rosin made from the secretions of insects which live in India. The
exact effect it produces in fireworks is not obtainable from other gums. The
common mixture of shellac and alcohol sold in hardware stores should be
avoided. Purchase the powdered variety, which is orange in color.
Sodium Oxalate Na C O
2 2 4
Used in making yellow fires. Available as a fine dust, which you should avoid
breathing.
Strontium Carbonate SrCO
3
Known in the natural state as Strontianite, this chemical is used for adding a
red color to fires. It comes as a white powder, in a pure, technical, or
natural state.
Strontium Nitrate Sr(NO )
3 2
By far the most common chemical used to produce red in flares, stars and fires.
Available in the technical grade as a white powder. It does double duty as an
oxidizer, but has a disadvantage in that it will absorb some water from the
air.
Strontium Sulfate SrSO
4
Since this chemical does not absorb water as readily as the nitrate, it is
often used when the powder is to be stored. In its natural state it is known as
Celestine, which is comparable to the technical grade used in fireworks.
Sulfur S
A yellow element that acts as a reducing agent. It burns at 250 degrees, giving
off choking fumes. Purchase the yellow, finely powdered form only. Other forms
are useless without a lot of extra and otherwise unnecessary effort to powder
it.
Zinc Dust Zn
Of all the forms of zinc available, only the dust form is in any way suitable.
As a dust, it has the fineness of flour. Should be either of the technical or
high purity grade. Avoid breathing the dust, which can cause lung damage. Used
in certain star mixtures, and with sulfur, as a rocket fuel.
The Chemistry of Pyrotechnics
Most pyrotechnic mixtures follow a very simple set of chemical rules. We'll go
over those now. Most mixtures contain an oxidizing agent, which usually
produces oxygen used to burn the mixture, and a reducing agent, which burns to
produce hot gasses. In addition, there can be coloring agents to impart a color
to the fire, binders, which hold the mixture in a solid lump, and regulators
that speed up or slow down the speed at which the mixture burns. These are not
all the possibilities, but they cover most all cases.
Oxidizing agents, such as nitrates, chlorates, and perchlorates provide the
oxygen. They usually consist of a metal ion and the actual oxidizing radical.
For example, Potassium Nitrate contains a metal ion (Potassium) and the
oxidizing radical (the Nitrate). Instead of potassium, we could instead
substitute other metals, like sodium, barium, or strontium, and the chemical
would still supply oxygen to the burning mixture. But some are less desirable.
Sodium Nitrate, for example, will absorb moisture out of the air, and this will
make it harder to control the speed at which the mixture will burn.
In the following examples, we'll use the letter "X" to show the presence of a
generic metal ion.
Note that Nitrates are stingy with the oxygen that they give up. They only give
one third of what they have.
Some Some
Nitrate Nitrite Oxygen
2XNO ---> 2XN0 + O
3 2 2
Chlorates are very generous, on the other hand. They give up all the oxygen
they have. Furthermore, they give it up more easily. It takes less heat, or
less shock to get that oxygen loose. Mixtures using chlorates burn more
spectacularly, because a smaller volume of the mix needs to be wasted on the
oxidizer, and the ease with which the oxygen is supplied makes it burn faster.
But the mixture is also MUCH more sensitive to shock.
Some Some
Chlorate Chloride Oxygen
2XClO ---> 2XCl + 3O
3 2
Perchlorates round out our usual set of oxidizing tools. Perchlorates contain
even more oxygen than Chlorates, and also give it all up. However, they are not
as sensitive as the Chlorates, so they make mixtures that are "safer". That is,
they're less likely to explode if you drop or strike them.
Some Some
Perchlorate Chloride Oxygen
XClO ---> XCl + 2O
4 2
Reducing agents, like sulfur and charcoal (carbon) simply burn the oxygen to
produce sulfur dioxide and carbon dioxide. It's usually best to include a
mixture of the two in a pyrotechnic mixture, as they burn at different speeds
and temperatures, and the proper combination will help control the speed of
combustion. Also, when extra fast burning speed is needed, like in rockets and
firecrackers, metal powder is often added. The finer the powder, the faster the
burning rate. The proportions change the speed, as well. Magnesium powder or
dust is often used for speed. Aluminum dust works, but not as well. Zinc dust
is used in some cases. Powdered metal, (not dust) particularly aluminum or
iron, are often used to produce a mixtire that shoots out sparks as it burns.
In rare cases, it is desirable to slow down the burning speed. In this case,
corn meal is often used. It burns, so acts as a reducing agent, but it doesn't
burn very well.
Coloring agents are very interesting. It's long been known that various metals
produce different colored flames when burned in a fire. The reasons are buried
in the realm of quantum physics, but the results are what matters, and we can
present them here. Note that if we use an oxidizing agent that contains a
colorizing metal, it can do a double job. It can produce oxygen and color.
Barium -Barium salts give a pleasant green color. Barium Nitrate is most
often used.
Strontium -Strontium salts give a strong red color. Strontium Nitrate is a
very convenient material for red.
Sodium -Sodium salts give an intense yellow color. So intense in fact that
any sodium compounds in a mixture will usually wash out other
colorizers. As has been said, Sodium Nitrate absorbs moisture from
the air, and so is not really suitable to impart color. Instead,
Sodium Oxalate is usually used. This does not absorb lots of water,
but has the disadvantage of being very poisonous.
Copper -Copper salts are used to give a blue color. Blue is the most
difficult color to produce, and it's usually not too spectacular.
Usually Copper Acetoarsenite (Paris Green) is used. This compound
contains arsenic, and is very poisonous. Since it still doesn't
produce a very memorable blue, it's often used with mercurous
chloride, which enhances the color, but is also poisonous, and
expensive, to boot.
Potassium -Potassium salts will give a delicate purple color, if they'e very
pure. The cheaper lab grades of potassium nitrate often contain
traces of sodium, which completely obscure the purple color. In
order to get the purple coloring, very pure grades must be used,
and you must be very careful to mix it in very clean vessels, and
scoop it from the supply jar with a very clean scoop. The color is
certainly worth the effort, if you can get it.
Some mixtures that burn in colors also contain binders, that hold the mixture
together in a solid lump. These lumps are usually referred to as stars. The
balls fired from a roman candle or the colorful showers sprayed from aerial
bombs are examples of stars. Depending on the mixture, the binder is either a
starch called dextrine or finely powdered orange shellac. A shellac-like
material called red gum is also used on occasion. In some mixtures, the shellac
powder also helps produce a nice color. Shellac mixtures are moistened with
alcohol to get them to stick together. Dextrine mixtures are moistened with
water.
If the colored mixture is to be used as a flare, it's just packed into a thin
paper tube. If it's to be fired from a roman candle, it's usually extruded from
a heavy tube by pushing it out with a dowel, and the pieces are cut off as the
proper length pops out. Stars fired from an aerial bomb are usually made by
rolling the moist mixture flat, and cutting it with a knife into small cubes.
Stars that are extruded are often called "pumped stars" those that are rolled
out are "cut stars".
The following are formulas for mixtures that burn with various colors. Parts
are by weight.
Red
Potassium Chlorate 9
Sulfur 2
Lampblack 1
Strontium Nitrate 9
bind with shellac
dissolved in alcohol
Blue
Potassium Chlorate 9 This one is inferior
Copper Acetoarsenite 2 Potassium Chlorate 12
Mercurous Chloride 1 Copper Sulfate 6
Sulfur 2 Lead Chloride 1
bind with dextrine Sulfur 4
in water bind with dextrin in water
Green
Barium Chlorate 8 Barium Nitrate 3
Lampblack 1 Potassium Chlorate 4
Shellac Powder 1 Shellac Powder 1
bind with alcohol Dextrine 1/4
Bind with alcohol
Yellow
Potassium Chlorate 8 Potassium Chlorate 8
Sodium Oxalate 3 Sodium Oxalate 4
Lampblack 2 Shellac Powder 2
Bind with shellac in Dextrine 1
alcohol or dextrine Bind with alcohol
in water
White
Potassium Nitrate 6
Sulfur 1
Antimony Sulfide 2
bind with dextrine in
water
Orange
Strontium Nitrate 36
Sodium Oxalate 8
Potassium Chlorate 5
Shellac Powder 5
Sulfur 3
Bind with alcohol
Purple (ingredients must be very pure)
Potassium Chlorate 36 This one has more of a lilac color
Strontium Sulfate 10 Potassium Chlorate 38
Copper Sulfate 5 Strontium Carbonate 18
Lead Chloride 2 Copper Chloride 4
Charcoal 2 Lead Chloride 2
Sulfur 12 Sulfur 14
bind with dextrine in bind with dextrine in water
water
Brilliant White
Potassium Perchlorate 12
Aluminum Dust 4
Dextrine 1
Bind with water
Golden Twinkler Stars - Falls through the air and burns in an on and off
manner. The effect is spectacular. A pumped or cut star.
Potassium Nitrate 18
Sulfur 3
Lampblack 3
Aluminum Powder 3
Antimony Sulfide 3
Sodium Oxalate 4
Dextrine 2
Bind with water
Zinc Spreader Stars - Shoot out pieces of burning zinc and charcoal. These
stars are much heavier than usual, and require larger charges if they're to
be fired from a tube.
Zinc Dust 72
Potassium Chlorate 15
Potassium Dichromate 12
Granular Charcoal 12
Dextrine 2
bind with water
Electric Stars - Stars that contain aluminum powder
Potassium Nitrate 15 Potassium Chlorate 60
Aluminum, fine 2 Barium Nitrate 5
Aluminum, medium 1 Aluminum, fine 9
Black Powder 2 Aluminum, medium 4
Antimony Sulfide 3 Aluminum, coarse 3
Sulfur 4 Charcoal 2
bind with dextrine in Dextrin 5
water bind with red gum in
water
Potassium Perchlorate 6
Barium Nitrate 1 Potassium Perchlorate 4
Aluminum 20 Aluminum, medium 2
Dextrin 1 Dextrin 1
bind with shellac in bind with shellac in alcohol
alcohol
Simpler Zinc Spreaders
Potassium Nitrate 14 Potassium Chlorate 5
Zinc Dust 40 Potassium Dichromate 4
Charcoal 7 Charcoal, medium 4
Sulfur 4 Zinc Dust 24
bind with dextrine in bind with dextrine in water
water
Willow Tree Stars - Use large amounts of lampblack -- too much to burn fully.
Gives a willow tree effect.
Potassium Chlorate 10
Potassium Nitrate 5
Sulfur 1
Lampblack 18
bind with dextrine in water
In future files, we'll look at using these mixtures to produce roman candles,
aerial bombs, and other effects. As always, don't forget that it's just plain
stupid to go buying all these materials from one chemical supply house. When
you buy it all as a group, they know what you plan to do with it, and they keep
records. If anyone goes investigating the source of homemade fireworks and
checks with your supplier, there will be a lead straight to you. Be sure to
cover your tracks.
PYRO4.TXT - Casings and General Construction, Part 1
This is part of a series of files on pyrotechnics and explosives. It's serious
stuff, and can be really dangerous if you don't treat it seriously. For you
kids out there who watch too many cartoons, remember that if a part of your
body gets blown away in the REAL world, it STAYS blown away. If you can't
treat this stuff with respect, don't screw around with it.
Each file will start with a set of safety rules. Don't skip over them. Read
'em and MEMORIZE 'em!! At the beginning, there will be a set of general rules
that always apply. Then there will be some things that you HAVE TO KNOW about
the materials you will be using and making this time. Read it thoroughly
before starting anything.
Pyrotechnic preparations and explosives are, by their very nature, unstable,
and subject to ignition by explosion or heat, shock, or friction. A clear
understanding of their dangerous properties and due care in the handling of
ingredients or finished products is necessary if accidents are to be avoided.
Always observe all possible precautions, particularly the following:
1. Mix only small batches at one time. This means a few grams, or at
most, an ounce or so. Don't go for big mixes -- they only make for
bigger accidents. The power of an explosive cubes itself with
every ounce. (9 Ounces is 729 times as powerful as one ounce.)
2. When weighing chemicals, use a clean piece of paper on the scale
pan for each item. Then discard the used paper into a bucket of
water before weighing the next ingredient.
3. Be a safe worker. Dispose of any chemicals spilled on the
workbench or equipment between weighings. Don't keep open
containers of chemicals on your table, since accidental spillage
or mixing may occur. When finished with a container, close it, and
replace it on the storage shelf. Use only clean equipment.
4. Where chemicals are to be ground, grind them separately, NEVER
TOGETHER. Thoroughly wash and clean equipment before grinding
another ingredient.
5. Mixing of batches should be done outdoors, away from flammable
structures, such as buildings, barns, garages, etc. Mixes should
also be made in NON METALLIC containers to avoid sparks. Glass
also should not be used since it will shatter in case of an
accident. Handy small containers can be made by cutting off the
top of a plastic bottle three or four inches from the bottom. Some
mixes may most conveniently be made by placing the ingredients in
a plastic bottle and rolling around until the mixture is uniform.
In all cases, point the open end of the container away from
yourself. Never hold your body or face over the container. Any
stirring should be done with a wooden paddle or stick to avoid
sparks or static.
Powdered or ground materials may also be mixed by placing them on
a large sheet of paper on a flat surface and then rolling them
across the sheet by lifting the sides and corners one at a time.
6. Never ram or tamp mixes into paper or cardboard tubes. Pour the
material in and gently tap or shake the tube to settle the
contents down.
7. Store ingredients and finished mixes where they will not be a fire
hazard away from heat and flame. Finished preparations may be
stored in plastic bottles which will not shatter in case of an
accident. Since many of the ingredients and mixes are poisonous,
they should be stored out of reach of children or pets, preferably
locked away.
8. Be sure threads of screw top containers and caps are thoroughly
cleaned. This applies also to containers with stoppers of rubber
or cork and to all other types of closures. Traces of mixture
caught between the container and closure may be ignited by the
friction of opening or closing the container. Throughout any
procedure, WORK WITH CLEAN CONDITIONS.
9. ALWAYS WEAR A FACE SHIELD OR AT LEAST SHATTERPROOF SAFETY GLASSES.
Any careful worker does when handling dangerous materials. Be sure
lenses and frames are not flammable.
10. Always wear a dust respirator when handling chemicals in dust
form. These small particles gather in your lungs and stay there.
They may cause serious illnesses later on in life.
11. Always wear gloves when working with chemicals.
12. Always wear a waterproof lab apron.
13. If you must work indoors, have a good ventilation system.
14. Never smoke anywhere near where you are working.
15. Make sure there are NO open flames present, and NO MOTORS (they
produce sparks inside.) No hot water heaters, furnaces, or pilot
lights in stoves!! Sparks have been known to very readily explode
dust floating in the air.
16. ALWAYS work with someone. Two heads are better than one.
17. Have a source of water READILY available. (Fire extinguisher,
hose, etc.)
18. Never, under any circumstances, use any metal to load chemicals or
put chemicals in. Fireworks with metal casings are worse to handle
than a live hand grenade. Never use any metal container or can.
This includes the very dangerous CO2 cartridges. Many people have
been KILLED because of flying fragments from metal casings. Again,
please do not use metal in any circumstance.
19. Always be thoroughly familiar with the chemicals you are using.
Some information will be included in each file, but look for
whatever extra information you can. Materials that were once
thought to be safe can later be found out to be dangerous stuff.
20. Wash your hands and face thoroughly after using chemicals. Don't
forget to wash your EARS AND YOUR NOSE.
21. If any device you've built fails to work, leave it alone. After a
half hour or so, you may try to bury it, but never try to unload
or reuse any dud.
22. If dust particles start to form in the air, stop what you are
doing and leave until it settles.
23. Read the entire file before trying to do anything.
24. NEVER strike any mixture containing Chlorates, Nitrates,
Perchlorates, Permanganates, Bichromates, or powdered metals don't
drop them, or even handle them roughly.
These rules may all look like a lot of silly nonsense, but let's look at one
example. When the move "The Wizard of OZ" was made, the actress who played the
good witch was severely burned when one of the exploding special effects got
out of hand. The actress who played the bad witch got really messed up by the
green coloring used on her face, and the original actor who played the Tin Man
got his lungs destroyed by the aluminum dust used to color his face. The actor
we know of as the tin man was actually a replacement. The point is, these
chemicals were being used under the direction of people a lot more knowlegable
of chemicals than you are, and terrible accidents still happened. Don't take
this stuff lightly.
***********************************
One of the biggest complaints I hear about firework formulas goes something
like, "This $@#!!* thing doesn't work! I wish someone would actually try the
things out before they upload them and waste my time!" Sometimes, I agree.
There are formulas for fireworks and explosives that have no chance of working,
and others that are downright dangerous. Many were obviously thrown together by
kids who never really tried them out, but thought they would look "big" in the
eyes of their friends if they wrote some "anarchy" files. Others copy formulas
from old manuals on pyrotechnics or explosives, or even old encyclopedias.
These will often work, but many were written before anyone thought about
safety, and were abandoned after enough people got blown away. Modern
literature on pyrotechnics often warn against some of these old formulations,
but they get copied anyway by people who either don't know or don't care that
they're dangerous. These files can then get passed around the country by others
who don't know of the danger.
Let me make my feelings clear. People who write such trash are dangerous and
should be treated the same as anyone who tried to slip you a computer virus or
trojan horse. At least a trojan will just screw up your hard drive. That can be
repaired, but you can't go buy a new set of eyes or fingers! If you don't
thoroughly understand what you're doing, go learn some more, first. There are
enough bad text files out there that taking the time to learn about dangerous
materials and mixtures will be your only defense against getting seriously
hurt.
But a formula may be completely correct and as safe as a pyrotechnic mixture is
expected to be, and you still may have trouble making it work. Often the reason
is that the kids who wrote the text files don't know how to package the
materials to get the proper results. Or they didn't know that it takes more
than just mixing chemicals to make some of the compositions work. If you've
ever mixed together the ingredients for gunpowder and watched its feeble
fizzling compared that to the hard flash of commercial gunpowder, you've seen
how important the proper processing can be. Sure, the first time you mixed a
few chemicals together it was a real kick just to set fire to a small pile of
it and watch it burn. But to make any kind of decent firework requires that a
properly designed casing be used to hold your magic powders, and then those
powders have to be made properly. A poorly designed casing or improperly
processed composition will louse things up as much as any lousy formula.
There don't seem to be any text files out there that discuss casings or
processing, though I've personally downloaded hundreds that contain formulas
for pyrotechnic mixtures. Now we can change all that.
So what's the big deal about casings? Just a paper tube, right? No, not
quite. A roman candle casing has to be able to handle repeated bursts so as
to fire its stars like a rifle does bullets. But if all the burning materials
inside change the inside diameter of the casing by too much, then the puffs
of gas that fire the stars into the air will escape around them and not push
them very high. Some of my early attempts didn't fire the stars out at all. A
skyrocket casing has to be light, strong enough not to burst even though the
pressures inside can be tremendous, and if it has a nozzle it has to grip it
tightly enough that it doesn't get blown out of the casing. A firecracker on
the other hand, has to be flimsy enough to burst yet strong enough to grip
its end plugs rather than let them rip loose and fire off of the end of the
casing. There are dozens of other examples, and if the casings aren't built
right then you've just built a dud.
So, learning all about various papers and glues isn't nearly as sexy as
playing with chemicals, but until you do you may as well just go lighting up
little piles of powder. You'll save a lot of money, and the results will be no
less spectacular. But there's a lot more to this than we can cover in the size
text file that's been typical of this series. We'll break this topic up into a
group of files that are a bit larger than usual. This will just be part 1 of
the discussion on casings and construction.
So, now that I've shamed you into wanting to learn about paper and glue,
let's get down to business. There are two kinds of paper tubes available.
These are called spiral wound and parallel wound. If you've ever tried to
wrap a sheet of paper around a dowel, pencil, or broomstick handle, you
produced a crude parallel wound casing. We'll be sharpening our skills in
this area. Spiral wound casings are made by wrapping thin strips around a
round dowel form in a spiral pattern. Tubes used to hold wrapping paper,
paper towels and toilet paper are made using this method, so check one of
these if you have trouble picturing the method. Spiral wound casings are
almost useless in fireworks as they have much less strength. Only
firecrackers like M-80s use spiral wound casings, and that's because they're
not supposed to be strong. So if you happen to come across some spiral wound
tubes that are the right size to cut up for M-80s, you may be able to use
them. Otherwise, they're probably not all that useful, even if they seem
thick enough.
Just so as not to worry anybody, you don't NEED a spiral wound tube for
M-80s. A suitably thin parallel wound tube will do the job just fine. Spiral
wound tubes are frequently used wherever possible because they're cheaper to
make. Machines that handle thin strips of paper don't make as many wrinkled
tubes as machines that have to handle wide sheets. Since we'll be doing our
work by hand, this need not bother us.
Glues
The good news here is that the materials won't be nearly as hard to come by
as some of the pyrotechnic mixtures mentioned in earlier installments. There
are different types of glue formulas, most being variations of flour paste,
which you can select, depending on what's convenient to you. If you don't
feel like doing the slimy work needed to make this muck, I'll mention that
I've had some success with commercial white glues, like Elmer's Glue All,
though this tends to make a casing that doesn't accept certain types of end
plugs very tightly. I wouldn't use it for rocket casings, and firecrackers have
to be specially constructed. It's also going to cost a lot more than flour
paste. You can experiment with it for small batches, if you like. It's also
possible to get passable results with batches of white school paste, thinned
down with enough water to make it flow. But if you're going to make a
reasonable number of casings, you'll need larger batches of glue, and you can
make it fairly cheaply and simply.
A good, homemade glue that will make strong casings is made by adding 4 1/2
cups of flour to 3 cups of boiling water and then adding 1/8 ounce of alum
(aluminum potassium sulfate). Stir this combination until it is consistent in
blend. When it's cooled, it's ready to use. The flour is the actual glue. The
alum helps fireproof the mess and helps act as a preservative. This is
important, as wet flour will eventually spoil, and so this mess has to be
used up fairly quickly. Don't count on saving it for more than a couple of
days and especially don't try storing it in a jar or other closed space. The
flour will spoil by fermenting, producing lots of gas, bursting your jar.
But if spoilage is a real problem, can we let the flour spoil BEFORE we make
the glue? This is not as silly a question as it sounds. By doing this, we
make a slop that can be kept a month or so, if it's also kept in a reasonably
cool, dark place. Just don't make it on a full stomach.
Pour anywhere from a few cups to a few bucketfulls of flour into a container
large enough to cover it with a good layer of water but still be only a third
full. How much water you use doesn't matter too much right now, as most of it
will be poured out later. Just make sure that you're making a batter, instead
of a dough. Stir it up good, but don't worry too much about little lumps.
That will be corrected later.
Now for the revolting part. Let the stuff sit for 2-3 days in a warm (90
degrees F) place and check it after then. If it hasn't begun fermenting by
then, drop in a few pinches of instant yeast. When the fermentation is finished
and there are no more bubbles forming, the flour will have settled as a gooey
layer at the bottom of a pool of revolting brownish liquid. Get rid of the
brown slop and note how much batter is resting in the bottom of the container.
Boil enough water so as to have a volume that's twice the size of the batter,
and pour it in slowly, stirring the flour briskly. It'll start out being easy
to stir, but will get thick in a hurry. If you're only making a few cups at a
time, it won't be heavy enough to hold still while you're trying to stir it, so
you might want to have the container clamped down solid.
If you did it all right, you should have a batch of clear, smooth paste that's
plenty sticky and fine for sticking your casings together. Since it's already a
spoiled batch of flour, it can't go bad a second time and needs no
preservatives.
If you plan to use any Chlorates in your fireworks you should also add some
potassium carbonate dissolved in water to your glue before using it to make any
casings. I always put it in, no matter what I plan to do. The reason for this
is that glue tends to deteriorate slightly, producing a slightly acidic
material. Old paper used in the casings can also become acidic. Any Chlorate
that comes in contact with an acid will produce tiny amounts of Chloric Acid,
which can ignite if you do anything more vigorous than just thinking about it.
Potassium Carbonate will counteract the effect of any acids, making your final
masterpiece much safer than it would be otherwise. After that, it's still
common practice to design fireworks so that no Chlorate bearing portions
actually touch any glue.
A super hard pyrotechnic cement can be made by mixing finely powdered Calcium
Carbonate (powdered chalk) with Sodium Silicate solution. The proportions will
vary depending on the amount of water in the Sodium Silicate, but you can make
a few small test batches to check what works best for your materials. The
Sodium Silicate should be thick enough to remind you of maple syrup, and can
either be thinned with distilled water or allowed to thicken by evaporation, as
needed. Stir in the Calcium Carbonate until you've got a thick, sticky mess.
When this stuff hardens, you won't be able to clean it off of your utensils, so
use items that you won't mind throwing away.
This material makes nice end plugs in large firecrackers, and can be mixed with
sawdust and a bit of red powdered tempra paint to make that nice, solid shell
that coats cherry bombs. But this stuff is rock hard and turns into a shower of
skin and eye piercing shrapnel once it bursts. Keep this in mind as you design
your little gems.
What Was That About Chlorates?
Materials like Potassium Chlorate and Barium Chlorate are among those that you
love and fear to use. Unlike the Perchlorates, which are much safer, Chlorates
form Chloric Acid in the presence of moisture (like humidity) and any kind of
acid material, and this can cause your mixtures to ignite on their own. If that
igniting mixture is inside a salute that's piled in a box with other salutes,
you can expect the whole thing to go up at once. Impressive to watch from a
distance, but if it was in the trunk of your car, you should expect to have to
answer a lot of questions to the authorities. And pay higher insurance. Yes,
there's nothing like Chlorates to make fireworks so thoroughly spectacular.
What to do? I normally avoid them, but have no problem with passing on formulas
that use them, as long as you realize what you're getting into. While there are
some places they should never be used, Chlorates are sometimes used in stars
that get fired from a roman candle or aerial bomb, because the speed with which
they get ejected can actually blow them out. Chlorate based mixtures just don't
blow out. If you want to use them, use small amounts and don't try to store
your creations over long periods of time. Keep them away from other fireworks.
We can neutralize an acid by adding a base (a Hydroxide) but bases tend to
absorb atmospheric moisture and screw up the burning of your mixture. A group
of compounds that act much like bases (Carbonates) also can counteract small
traces of acids. Make sure that your glue contains carbonates to counteract the
effect of any acids that may form. If you want your eyes and fingers to last a
lifetime, it's also a good idea to add some sort of Carbonate to the firework
mixture. This will counteract any acid, but adds nothing at all to the
performance of the powder. Furthermore, they can change the color that the
powder burns. We've covered the elements that add color in an earlier file, and
know, for example that Strontium salts give a red color. So adding Strontium
Carbonate to the mixture can at least give us some coloring. Barium Carbonate
can give a green color. While Sodium Carbonate might give us a yellow though,
it also absorbs atmospheric moisture and will keep your mixture from burning
properly.
The use of carbonates is particularly important if your mixture contains both a
Chlorate and Sulfur. Sulfur can form both traces of Sulfur Dioxide and Hydrogen
Sulfide, and BOTH of these become acidic in water. One of the earlier files in
this series showed how a mixture of just Potassium Chlorate and Sulfur will
explode when you strike them. The trace amounts of acid that are always present
in sulfur in the air can form enough Chloric Acid to explode when hit. Now, if
you let it sit by itself for a long time, it may decide to ignite by itself.
Then again, it may not. A potassium Chlorate-Sulfur bearing pyrotechnic mixture
may behave properly the first 99 times you try it, and then bite you on the
hundredth. If you want to experiment with Chlorate-Sulfur formulas, use small
amounts only, add a carbonate before using them in any real fireworks, and
absolutely avoid any of the ancient formulas that use Chlorates and Sulfur in
firecrackers. For that matter, Chlorates mixed with anything in a firecracker
are a bad idea.
Commercial Safety Fuse
This handy item consists of a string coated with gunpowder, which is in turn
<EFBFBD>wrapped with light twine, and finally coated with a red or green varnish. The
varnish is apparently applied without a great deal of thinner in it, because it
covers the twine layer without actually soaking into it. This waterproofs the
fuse, and it can get quite moist for a long time and still work, provided that
you don't crack the varnish layer by bending it too severely. If you do, the
fuse will still work fine as long as it stays dry. This type of construction is
built around its being made by machine. You wouldn't want to make it this way
by hand, though we'll talk in a minute about a way to make a somewhat inferior
waterproof fuse.
The red and green varnishes are more than just decorative. They tell you
something about how the fuse works. All fuses will spit a stream of burning
crud from their ends as they burn. Sometimes people who are the first to
describe things have no imagination, and it must have been the case here,
because this property is known as end spit. Some fuses also spit sparks to the
side, and not surprisingly, this is called side spit. Consider that a fuse that
has little side spit may not light some of the more difficult to ignite
mixtures until it burns to the very end of the fuse and fires its last spit out
of the far end. Some of the very difficult to ignite mixtures may not ignite at
all. Fuse with side spit will be blasting away at the mixture its inserted into
through the entire length of its insertion. Unfortunately, the fuse with side
spit isn't nearly as tough as the fuse that only has end spit. If you have a
choice of fuse types, you can make your selection according to what you have
available. Fuse with mostly end spit is colored red, while fuse with a good
amount of side spit is colored green. (And I'll bet you thought it was just a
decoration!)
Black Match and Quick Match
These items have nothing to do with the matches you strike to light your
fireworks. In the jargon of pyrotechnics, match is a simple fuse made around a
string core. Black match is used much like you would use ordinary fuse. That
is, it gives a time delay before the firework actually goes off. You should
want this to happen most of the time. Quick match is just the opposite. It
burns from end to end very quickly. This is used where you want to start
several fireworks at once, but light only a single fuse. This happens most
often in commercial fireworks displays, where a large array of various colored
flares (lances, in pyrotechnic lingo) must all be lit together to form a
picture of some sort on a wooden framework set on the ground. You may not have
much need for quick match, but it's interesting information, and if you know
why it works you don't cause it to happen accidentally.
To make black match, you start with cotton twine. Different
thicknesses will give different results. Thicker twine will hold more powder
and will burn better, but heavy cord is too much. Try as many kinds as you can.
Avoid synthetic fibers; they can keep your match from working properly. If you
aren't sure wether or not the twine is synthetic, try to burn a small length of
it. Cotton will burn with a tiny flame and leave a very mundane ash. Synthetics
will clearly melt as they burn.
The prime ingredient of black match is meal powder. This is the name used in
the pyrotechnic field for an unprocessed gunpowder mixture. You can just powder
the ingredients by hand in a mortar and pestle (do each one separately!) and
then just mix them in a plastic bowl. There's no need to use a powder mill, as
will be described below. The black match formulation consists of 10 parts meal
powder and one part of either gum arabic or dextrine. These are two different
types of glues, and you should make your selection based on the humidity. Gum
arabic is better in dry climates and dextrine is better in higher humidity. Add
water and stir the mix until all the grains are wet. It will probably take a
bit of work to get it spread all around, as the fine dust likes to form dry
patches. After you think you've got it all damp, let it all sit for a few
minutes so that any dry areas too small to see will have a chance for the
moisture to soak in. After this, add lots more water and a bit of alcohol stir
until you have a disgusting black mush. The amounts of liquid will be roughly a
pint of water and an ounce of alcohol for every pound of meal powder, but you
may need a bit more or less, depending on the thickness of the string you use.
Don't take these proportions as an indication of the size of your first batch,
though. Start small.
Take a 2 or 3 foot length of the string and stir it up in the mush, squishing
it in so as to get it completely soaked. Slowly draw it out, dust it with some
dry meal powder and hang it to dry. Be careful while stirring, making sure that
you don't wind the string into knots. If you do, discard the string and start
again. Since this piece of garbage will become very flammable when it dries
out, I'd suggest either burying it or cutting it into shorter lengths and
flushing it down the can.
Don't hang up these things anywhere there's an open flame or a chance of a
spark. If one goes off, the sparks it spits off should have a reasonably good
chance of setting off any others hanging nearby, and if you don't end up
starting a fire, you'll at least lose a lot of hard work in a hurry. If you
need longer lengths of this stuff, you'll have to modify your technique, but be
assured it's been done by others, and you can too. As I've never needed more
than a few feet at a time, I can't speak from experience, though. Just use your
head and you'll surely work out a good technique.
This material, when dry, is black match, and will burn as a crude fuse. If you
try to bend it, the powder will crumble off, leaving spot where the fuse may go
out. Obviously, you can't use this everywhere you'd use waterproof safety fuse,
but there are times where it's useful.
All right then, if this stuff is so fragile, why not enclose it in a sort of
tube, to beef it up? That should protect it from crumbling, right? Well, it'll
certainly protect it, but it will also act entirely different. The match will
burn erratically, sometimes normally, sometimes in fast jumps. If the tube is
wide enough, say, 3/16 to 1/4 inch inside, the sparks that the burning powder
spits out will fly down the tube, igniting more powder, and causing the flame
to flash from one end of the tube to the other in almost no time at all. This
is called Quick Match and the tubes can be made by rolling a few layers of
newspaper over a 1/4 inch steel rod and quickly pulling the tubes off to dry.
You can then run a length of black match through the tube, and wherever you
want to attatch a firework to the tube, just poke a small hole and insert a
piece of black match.
Don't try to wrap a tighter tube around a piece of black match to try to
strengthen it. You won't be able to count on any sort of predictable behavior
out of the thing, and if you were counting on having a little time to head for
cover and the flame just flashes through the tube, well, that could abruptly
change your plans for the next few months. Safety fuse isn't hard to get and
it's not all that expensive. Use it where it's needed.
If you absolutely can't get safety fuse, you can coat the black match with
spray on plastic, available from handicraft stores, and when that's dry, brush
on a layer of liquid rubber mold compound, which you can often get from the
same place. One or more layers of the rubber will keep the powder from
crackling off, but absolutely don't skip the spray on plastic, first. The
plastic will put a temporary waterproof coating on the powder, which is needed
since the liquid rubber is water based, and will wet the powder and then dry on
the surface, sealing in the water. Such fuse would be very likely to go out at
an inopportune time. Feel free to experiment with various brush on varnishes as
a waterproofing, but the convenience of spray application has many advantages.
Firecracker Fuse
The tiny firecrackers that come in packs of 20 or more, all braided together,
show the most unusual fuses. A thin tissue tube that has been somehow filled
with the tiniest string of powder. Most texts on fuse give this item a quick
mention as being difficult to make and suggest that their authors tried to do
it and gave up. As it turns out, these are not all that difficult to make once
you get the procedure right. We'll start out making a fuse that's about twice
as thick as those tiny things, and as you develop the proper technique, you'll
be able to scale it down to make something that looks and acts like the real
thing. Most attemps fail when the individual starts out trying to make the fuse
as thin as the commercial version, and eventually gives up. What you really
need to do is first develop the basic skills on something larger. After that,
it's easy to work your way down. To be honest, this kind of fuse is not widely
useful considering the time needed to make it, but for those times when you do
have a use for it, this knowlege can be very handy.
It's very important to start with the right kind of paper. The paper used in
the orient is not availabe here, but reasonable substitutes can be found.
What's needed must be tissue-thin, yet fairly firm and strong. The papers used
in facial tissues and toilet paper are far too flimsy. The real dedicated model
airplane builders who work in balsa wood have used various tissues, and one
material, called silkspan, can get reasonable results. But a perfectly adequate
paper can be scrounged for free. That crackly kind of tissue paper that's used
by stores to pack clothing into gift boxes so that it doesn't flop around in
the box will work just fine. If you don't know what I'm talking about, it's
time you graduated up from blue jeans and T-shirts.
You'll have a difficult time of it if you don't start out by making or getting
a few simple tools. The first item you'll need is a piece of bent sheet metal
or a piece of metal angle. Angle is sturdier and is easier to use. The item
should be about 8-10 inches long. If you use sheet metal, make it about 2
inches wide and bend it down the middle along its length. You should have a
long trough with an angle of 90-100 degrees. Next, you'll need a cradle to hold
the trough so that the bend can be at the lowest point. Two strips of wood,
attatched to a base, will do the job. Finally, you'll need tiny, spoonlike
tools for dispensing and spreading the powder. Some biological supply houses
sell a stainless steel spatula that's ideal. It consists of a thin metal rod
about the thickness of a coat hanger, with one end flattened out into a 1/4
inch wide paddle that's great for spooning out tiny amounts of powder. The
other side has a more pointy paddle that makes it much easier to spread out the
powder.
Make a weak glue by dissolving a bit of dextrine in water. Find a SHARP pair of
scissors and cut out some pieces of the crackly tissue about 3 inches long and
3/4 inch wide. Get pieces that have no wrinkles. The pieces should be quite
straight, which you'll have trouble doing if the scissors are not really sharp.
Fold the tissue along its length, as shown;
|<----------------- 3 inches ------------------>|
| |
\/
----------------------------------------------- ----------
| | 1/4 inch
---------- |-----------------------------------------------| ----------
/\ | / | /\
1/2 inch | / |
\/ | fold here |
---------- -----------------------------------------------
Unfold the sheet and set it down into the trough, as shown in the cross
section. The picture is angled incorrectly, since typewritten characters give
only a limited ability to show graphics. The trough should look like an
"arrowhead" pointing downward.
/
/
/ /
/ /
... / /
powder ------> .... / /
...... / /
paper ---> _______________________________/ /
sheet metal -----> __________________________________________/ <---- First
or metal angle fold
Use the wider of the spoon tools to put a crude line of freshly mixed meal
powder along the length of the fold. Next use the pointier tool to try to
spread the powder out evenly. A few properly placed taps should cause the
powder to spread out uniformly. This works much better if the trough is made of
angle instead of sheet metal. It's not likely to work at all if the meal powder
is a day or more old, since any humidity will probably have started it to cake
together. It's difficult to describe how much powder to put in, but it's easy
to describe what it will look like when it's done. Lift the paper out of the
trough and refold the tissue, holding in the powder. Once folded, the powder
should fill the folded section about halfway.
_________________________________________________________
| |
| |
| |
| |
| |
| |
|_________________________________________________________|
| |
| | Crease and
| | <---- fold here
| ******************************************************* |
| ********************* powder ************************** |
----------------------------------------------------------- <--- First
fold
Next, crease the paper right above the powder and fold it upward, enclosing the
powder in a second fold. This may take a little practice, but it's not as hard
to do as it might first appear.
_________________________________________________________
| |
| |
| |
| |
| |
| |
|_________________________________________________________|
| ******************************************************* | <--- First
| ********************* powder ************************** | fold
----------------------------------------------------------- <--- Second
fold
Next, roll the folded powder section up into the remaining paper. Don't worry
if it's not perfectly smooth, but try the best you can. Give the slender tube
you've made a gentle, rolling twist. Don't twist it too tight, or you'll rip
it. When it's about as thin as it's going to get, dip your finger in the
water/dextrine mix, and quickly run it along the length of the fuse. Be careful
not to use too much. It should not be soaked, just dampened along one side.
Leaving the fuse twisted, set it down with a small weight on each end to keep
the twist in the fuse. The weights will flatten the ends, and when it's dry
you'll want to cut off at least 1/4 inch from each side. These parts won't have
enough powder.
You can experiment with making longer lengths of fuse. Three inches is a
reasonable size to learn on, and you'll probably be able to add another inch or
two, though you may not find the extra effort to be worth it. It's better to
practice making thinner fuse. What you've just made is probably about twice as
thick as is found in commercial packs of firecrackers. Work your way down to
papers only 1/2 inch wide, using a smaller amount of powder. You are now an
expert fusemaker.
Processing Gunpowder
Gunpowder is one of those items that every budding pyro knows something about,
but few really understand. The standard formula shows this to be 75% Potassium
Nitrate, 15% Charcoal, and 10% sulfur. But just powdering and then mixing these
ingredients makes a powder that's just a weak parody of real gunpowder. Real
gunpowder is made using certain commercial processing methods that make it burn
much more fiercely. While we can't copy these methods exactly, we can make a
pretty decent approximation that can be used in place of gunpowder in most
fireworks formulas. By the way, the unprocessed mixture that most people think
of as gunpowder is known in the pyrotechnic trade as "meal powder".
One secret of good gunpowder is in making the individual ingredients as finely
powdered as possible. Just running them around in a mortar and pestle for a few
minutes won't do it. The other secret of good powder is to mix the ingredients
thoroughly. Both of these must be done better than can be done by hand. Simple
mechanical means will be used.
If you've ever looked at commercial gunpowder, you've noticed that it comes in
rock-hard granules of various sizes. It looks nothing like the gray meal powder
you're probably used to making. If the ingredients are properly ground and
mixed, then a tiny amount of water can be added (just enough to moisten it all)
and the wet mass is pressed into a cake about 1/2 inch thick to drive out any
air that may remain. The cake is kept pressed until it's dried solid and is
very hard. This may take several days to a week. During this time, the moisture
in the mix has dissolved a tiny bit of the Potassium Nitrate, which is very
soluble in water. When the particles are tiny enough and the air between the
particles is driven out, the Potassium Nitrate will actually RECRYSTALLIZE
AROUND the particles of Sulfur and Charcoal, and will become very hard. It is
then crushed with wooden tools (or brass or aluminum tools -- no iron or steel
-- it can produce sparks!!!) and the particles are sorted by size by running
them through various mesh sized screens.
Mixing and powdering the ingredients requires you to make or buy a simple
machine. Happily, the same machine can be used for both operations. The machine
is a gemstone tumbler, and for small amounts of powder, a 3 lb. tumbler is
about right. This will allow making 1/2 pound batches of powder. The reason a 3
lb. tumbler is being used for mere half pound loads, is that it will also
contain about 2 pounds of brass pellets that you'll have to cut from half inch
brass bar stock into 1/2 inch lengths. Don't cut the brass by hand with a
hacksaw. If you have access to a power hacksaw, use that, otherwise, find a
local machine shop that can do the job for you. You'll be glad you did, trust
me. While bars of iron or steel are more readily available and cheaper, they
will also make sparks and blow up your powder mill. Brass won't spark at all.
Don't use anything else. After your pellets are cut, you'll want to smooth off
the burrs on a belt sander or, shudder, by hand filing. This is all a lot of
work, but you only have to do it once.
If you want to try making your own tumbler, you'll want to be rolling a soft
plastic bottle about a quart in volume. Don't even think of using metal, glass,
or hard plastic. In either case, an explosion would send deadly shrapnel
flying in all directions. While the hard plastic might not be quite as deadly
as metal, it has the added disadvantage of not showing up in an X-Ray. Think
about it.
The bottle should roll at perhaps 10-12 RPM. The usual way to roll a bottle for
mixing purposes is to have a roller attatched to a low speed motor, and another
free rolling roller a couple of inches away. When the bottle is placed on top
of, and parallel to the two rollers, all three will turn. Don't forget that
electric motors make sparks and sparks can touch off powder. Make the shaft
from the motor to the roller as long as you can, enclose the motor as best you
can, and keep EVERYTHING as clean as you possibly can.
If you buy a gemstone tumbler, make sure it has a solid rubber barrel. There
are metal barrels available, but you should realize by now why you'd avoid that
kind. Some cheap tumblers have plastic barrels. Again, you should avoid hard
plastic.
Once you have the proper equipment, put the brass pellets into the barrel and
dump in the Potassium Nitrate. Now, run the mill for four (yes, I said four)
hours. The Potassium Nitrate must be quite dry, or you'll be wasting a lot of
effort for nothing. It's safe to warm it in a 300 degree oven for a few hours
if it contains moisture, but you'll want to let it cool down in a closed
container before you mix it with anything. Since the Potassium Nitrate will
start caking on a humid day, you may wish to select a dry day before you begin.
After you're done, remove the Potassium Nitrate and put it in a SEALED
container. If you don't do this, the stuff will begin caking from any traces of
humidity, and the final material will actually be less finely powdered than you
want. Next, put in the charcoal, and run it for two hours. Once charcoal is
powdered that finely, you'll make thoroughly nasty black dust clouds when you
try to pour it, so don't take it out of the mill until everything's done. Next,
add the Potassium Nitrate back in and the Sulfur, which normally comes finely
powdered. Now all three ingredients will be in the mill and you should run it
all for six (!!!) hours.
These times are really minimum times if you want to make decent powder. You'll
find that the powder will be much fiercer if you double all these mixing times,
but the time needed will start becoming impractical. Once this is all done, you
should take out the powder, add enough moisture to get it to cake together and
press it into a flat cake. I've had some success with two heavy boards held
together on one end with a wide hinge. These swing together leaving a half inch
gap between them and are clamped together on their free ends with a metal
C-Clamp. The boards should have several layers of waterproof varnish,
otherwise they'll start warping, they'll leach out some of the dissolved
Potassium Nitrate from your powder, and they'll probably become much more
flammable than you'd like them to be. Let the thing sit in a dry, cool place
for a couple of weeks. It should be away from any sparks or flames, including
electric motors, and should be far enough away from other flammable materials
that you won't have a fire on your hand if it accidentally ignites.
After it's dry and hard, crush and screen it, and you're done.
One final word on this. The extreme solubility of Potassium Nitrate allows all
the recrystallization that makes good gunpowder possible. But recrystallization
is a problem when it causes the Potassium Nitrate to cake in the container. If
you get it in jars, you'll probably have to scrape or chip out the chunks you
need. If you buy it in 100 lb sacks, you'll have to break pieces off with a
sledge hammer. Don't forget that this unpleasant property also happens at the
microscopic level, making tiny particles clump together into larger ones, as
the clock ticks. Time is your enemy when you need to have your Potassium
Nitrate in a fine powder. Use it as quickly as you can once you've powdered it.
Don't powder it today for use tomorrow. Even if it looks okay the next day, you
can be sure you've lost some of the work you've put into it, and that the
performance of your final product will suffer.
Rolling Casings
This is one of those very important skills that always seem to be ignored in
files that describe the pyrotechnic arts. Yet, the properly built casing will
make the difference between sucess and failure of your creations. For most
casings, brown Kraft paper will work very well. Everyone who's in any way
involved with modern civilization is familiar with this stuff as the brown
paper bags used by supermarkets, hardware stores, and many other businesses.
It's tough and will absorb the glue, making a tough casing. While stores in
many areas are switching to plastic bags, it should be possible to save enough
bags to meet your needs. If not, you can buy the paper in large rolls from
paper supply houses. While it comes in various thicknesses, choose something
that's comparable to the paper bags, which seem to be well suited for our
needs.
While the simplest casings are just made by rolling a piece of paper over a
rod, and then sliding it off and gluing the end closed, these are not of
very much use. Most casings need to have glue between the layers of paper
to make them hard, have to be cut to the proper length while they're still
wet and mushy from the glue, and you have to use care not to glue the
casing to the rod you're winding it on.
You have two choices as to the type of rod to use to roll your casings. A
metal bar will last longest, won't swelll from the moisture in the glue,
and won't easily stick to a stray glue droplet, but is more expensive,
takes more work to cut to size, and will quickly dull the knife blade that
will be used to cut the casing. A wooden dowel is cheap, easy to cut to
length, available in a wide variety of sizes. It will also have to be
replaced more frequently if you cut your casings while they're on it,
because the knife blade will quickly cut deep grooves into the wood. It
also requires extra care to keep from gluing the casing to it. We'll
describe the procedure for wrapping a casing around a wooden dowel. If you
choose to use a metal rod, you can ignore the extra cautions that using
wood will require.
Start with a sheet of paper. One dimension will be about an inch and a half
larger than the length of your casing. The other dimension will have to be
learned from trial and error, and will have to do with how thick you want
the casing wall to be. Wrap one and a half turns of the paper around the
dowel and give the dowel a twist so that the paper is wrapped tightly with
no slack or wrinkles. Unwrap about a quarter turn, enough so that it still
remains tightly wrapped but just barely so. Next, put glue on the paper
near the crack where the wrapped portion meets loose portion and start
wrapping the paper by rolling the dowel PYRO5.TXT - Casings and General Construction, Part 2
This is part of a series of files on pyrotechnics and explosives. It's serious
stuff, and can be really dangerous if you don't treat it seriously. For you
kids out there who watch too many cartoons, remember that if a part of your
body gets blown away in the REAL world, it STAYS blown away. If you can't
treat this stuff with respect, don't screw around with it.
Each file will start with a set of safety rules. Don't skip over them. Read
'em and MEMORIZE 'em!! At the beginning, there will be a set of general rules
that always apply. Then there will be some things that you HAVE TO KNOW about
the materials you will be using and making this time. Read it thoroughly
before starting anything.
Pyrotechnic preparations and explosives are, by their very nature, unstable,
and subject to ignition by explosion or heat, shock, or friction. A clear
understanding of their dangerous properties and due care in the handling of
ingredients or finished products is necessary if accidents are to be avoided.
Always observe all possible precautions, particularly the following:
1. Mix only small batches at one time. This means a few grams, or at
most, an ounce or so. Don't go for big mixes -- they only make for
bigger accidents. The power of an explosive cubes itself with
every ounce. (9 Ounces is 729 times as powerful as one ounce.)
2. When weighing chemicals, use a clean piece of paper on the scale
pan for each item. Then discard the used paper into a bucket of
water before weighing the next ingredient.
3. Be a safe worker. Dispose of any chemicals spilled on the
workbench or equipment between weighings. Don't keep open
containers of chemicals on your table, since accidental spillage
or mixing may occur. When finished with a container, close it, and
replace it on the storage shelf. Use only clean equipment.
4. Where chemicals are to be ground, grind them separately, NEVER
TOGETHER. Thoroughly wash and clean equipment before grinding
another ingredient.
5. Mixing of batches should be done outdoors, away from flammable
structures, such as buildings, barns, garages, etc. Mixes should
also be made in NON METALLIC containers to avoid sparks. Glass
also should not be used since it will shatter in case of an
accident. Handy small containers can be made by cutting off the
top of a plastic bottle three or four inches from the bottom. Some
mixes may most conveniently be made by placing the ingredients in
a plastic bottle and rolling around until the mixture is uniform.
In all cases, point the open end of the container away from
yourself. Never hold your body or face over the container. Any
stirring should be done with a wooden paddle or stick to avoid
sparks or static.
Powdered or ground materials may also be mixed by placing them on
a large sheet of paper on a flat surface and then rolling them
across the sheet by lifting the sides and corners one at a time.
6. Never ram or tamp mixes into paper or cardboard tubes. Pour the
material in and gently tap or shake the tube to settle the
contents down.
7. Store ingredients and finished mixes where they will not be a fire
hazard away from heat and flame. Finished preparations may be
stored in plastic bottles which will not shatter in case of an
accident. Since many of the ingredients and mixes are poisonous,
they should be stored out of reach of children or pets, preferably
locked away.
8. Be sure threads of screw top containers and caps are thoroughly
cleaned. This applies also to containers with stoppers of rubber
or cork and to all other types of closures. Traces of mixture
caught between the container and closure may be ignited by the
friction of opening or closing the container. Throughout any
procedure, WORK WITH CLEAN CONDITIONS.
9. ALWAYS WEAR A FACE SHIELD OR AT LEAST SHATTERPROOF SAFETY GLASSES.
Any careful worker does when handling dangerous materials. Be sure
lenses and frames are not flammable.
10. Always wear a dust respirator when handling chemicals in dust
form. These small particles gather in your lungs and stay there.
They may cause serious illnesses later on in life.
11. Always wear gloves when working with chemicals.
12. Always wear a waterproof lab apron.
13. If you must work indoors, have a good ventilation system.
14. Never smoke anywhere near where you are working.
15. Make sure there are NO open flames present, and NO MOTORS (they
produce sparks inside.) No hot water heaters, furnaces, or pilot
lights in stoves!! Sparks have been known to very readily explode
dust floating in the air.
16. ALWAYS work with someone. Two heads are better than one.
17. Have a source of water READILY available. (Fire extinguisher,
hose, etc.)
18. Never, under any circumstances, use any metal to load chemicals or
put chemicals in. Fireworks with metal casings are worse to handle
than a live hand grenade. Never use any metal container or can.
This includes the very dangerous CO2 cartridges. Many people have
been KILLED because of flying fragments from metal casings. Again,
please do not use metal in any circumstance.
19. Always be thoroughly familiar with the chemicals you are using.
Some information will be included in each file, but look for
whatever extra information you can. Materials that were once
thought to be safe can later be found out to be dangerous stuff.
20. Wash your hands and face thoroughly after using chemicals. Don't
forget to wash your EARS AND YOUR NOSE.
21. If any device you've built fails to work, leave it alone. After a
half hour or so, you may try to bury it, but never try to unload
or reuse any dud.
22. If dust particles start to form in the air, stop what you are
doing and leave until it settles.
23. Read the entire file before trying to do anything.
24. NEVER strike any mixture containing Chlorates, Nitrates,
Perchlorates, Permanganates, Bichromates, or powdered metals don't
drop them, or even handle them roughly.
These rules may all look like a lot of silly nonsense, but let's look at one
example. When the move "The Wizard of OZ" was made, the actress who played the
good witch was severely burned when one of the exploding special effects got
out of hand. The actress who played the bad witch got really messed up by the
green coloring used on her face, and the original actor who played the Tin Man
got his lungs destroyed by the aluminum dust used to color his face. The actor
we know of as the tin man was actually a replacement. The point is, these
chemicals were being used under the direction of people a lot more knowlegable
of chemicals than you are, and terrible accidents still happened. Don't take
this stuff lightly.
***********************************
We'll only be using a few chemicals this time. Here's the list:
Potassium Perchlorate KClO
4
A poisonous oxidizer, usually white but sometimes a slightly pink powder. Much
more stable than its Chlorate brother, it can often be substituted for it to
make a mixture safer.
Sulfur S
A yellow element that acts as a reducing agent. It burns at 250 degrees,
giving off choking fumes. Purchase the yellow, finely powdered form only.
Other forms are useless without a lot of extra and otherwise unecessary effort
to powder it.
Aluminum Powder Al
An element added for brilliance and to speed up the burning rate of a mixture.
A silvery powder, it often contains small amounts of finer dust that can be
hazardous if stirred up in the air and inhaled. Not nearly as dangerous or as
flammable as when in dust form, but still best to use with some caution.
Sodium Salicylate HOC H COONa
6 4
A white powder that functions as a reducing agent. Not nearly as effective as
other more common reducing agents, so used only when it gives a special
advantage, as in whistles.
Last time, we were discussing construction techniques for some small salutes.
If you followed the directions carefully, you should have made some reasonably
large noises. These little training salutes looked about the same size as an
M-80 or a Silver Salute, but were nowhere nearly as powerful. This was
intentional. Since these things are thoroughly nasty, we started small, though
tried to keep it from becoming obvious. The larger the volume of space inside
the tube, the more powder we can put in, and the more powerful it will be.
Our training salutes had a 7/16" Inside Diameter, was 1 1/4" long, and had
1/4" end caps that take up space that then can't hold powder. The volume of a
cylinder is V = Pi * R * R * L. R is one half of the inside diameter or 7/32".
L is the tube length, minus the size of the two end caps, or 3/4". Pi is about
3.14. This gives us a volume of .113 square inches.
A Silver salute has an Inside Diameter of 1/2", and an M-80 has an inside
diameter of 9/16". Each of these has a length of 1 1/2", and uses only about a
1/8" end cap, because it used the rock-hard (and shrapnel producing)
pyrotechnic cement we learned of last time, instead of the safer paper plugs
we used. Applying the same formula, the silver salute encloses a volume of
.245 square inches, or more than twice the volume of the training salute. The
M-80 encloses a volume of .310 square inches, which is nearly three times that
of the training salute. When we consider that explosive goes up roughly with
the cube of the amount of explosive, we see that small changes in the
dimensions of a salute can bring a huge change in its power. Of course, if you
read the safety rules printed at the beginning of every one of these files,
you will have figured that out for yourself. If you want to make larger
salutes, and I just know you will, it would be a good idea to not use the
pyrotechnic cement, and just make the casing a bit longer so that the paper
end plugs can be used. You can do what you want, but if you perforate your
eyeballs with splinters of pyrotechnic cement, you'll miss out on reading part
6 of this series, and that would really be a pity.
Cherry Bombs
Cherry bombs have been known to be terribly dangerous, largely because they
tended to be coated with the pyrotechnic cement, often stretched out with
cheaper sawdust. These have blinded a great many people. Their reputation has
been further smeared by street punks who dip cherry bombs in glue, then in
BB's, and let them dry into little anti-personnel grenades for hurling into
rival street gangs. The sheer stupidity of such an action can't be adequately
expressed. We'll talk about a safer way to make and use these items.
Cherry bombs start with two small paper cups, one of which fits inside of the
other, to make a crude ball. The smaller ball gets a hole poked in it, and the
fuse inserted and glued in place. The smaller cup is then filled about halfway
with flash powder, the salute powder mentioned last time works nicely, and the
larger cup is glued in place. In the old days, the ball was then held by the
fuse and dipped in the pyrotechnic cement, and set aside to harden. Instead,
without letting the glue on the two cups dry, cover the entire ball with
several layers of glue-soaked paper strips. Make the strips of brown kraft
paper (supermarket paper bags will do) about 2 inches long and a quarter of an
inch wide. These have to be pressed with your fingers onto the outside of the
cups. The entire thing should end up covered with four or more layers of the
paper strips. It's best to put on all the layers at once. If by any chance
the thing should go off while you're making it, the soggy paper will just
split open, and you'll get burned. But once you let some of the layers dry,
you have a potentialy explosive device and could be damaged severely if it
went off.
Making the little paper cups is an interesting exercise in ingenuity. Since
dealers in pyrotechnic materials will sell these cups for less than ten cents
a set, (for smoke bombs only, of course!!) they're hardly worth the effort to
make yourself. But if your funds are limited, or you just enjoy doing it
yourself, we'll look at a couple of ways to do it.
A piece of soaking-wet brown kraft paper can be formed over a round bulge or
into a rounded impression. If two or three such sheets are formed over or
stuffed into such a shape, with a layer of glue between each, they'll dry into
nice cup shapes. Controlling the shapes of the cups can be tricky, but the
outside cup must be able to fit snugly over the inside one. If it's too small,
it won't fit at all, and if it's too big, it will be hard to glue to its mate.
If you think about it, you don't have to control both the inside and outside
dimensions of each cup. The outside of the small cup has to match the inside
of the large cup. A round pin-shaped form will give good control over the
INSIDE diameter, so a round pin should be used to form the OUTSIDE cups. A cup
shaped indentation allows control over the OUTSIDE diameter, so it should be
used to form the INSIDE cup. The outside diameter of the pin should match the
inside diameter of the indentation.
Matching the two parts is easy if you have access to a machine shop. With a
lathe and some decent measuring tools, you can cut the indentation out of a
block of metal and turn the round head over a piece of metal bar stock.
Machinable plastic will work fine too, but it's just not as nice, and stinks
when you machine it. Iron or steel will rust, changing the carefully machined
dimensions and anyway, they're too much of a hassle to cut. Avoid them. Wood
of any kind will warp, swell, and otherwise deform itself. It won't work.
Aluminum won't rust and is easy to machine. This is best if your machining
experience is limited. Brass is really NICE, though. Being able to machine
your own parts is also nice if you plan to make a dozen or so of each part so
that you can make more than one set of cups at the same time.
Okay, so what do you do if you don't have access to a machine shop? Well, a
little walk through a hardware store will give you the right materials, and
you can even make multiple sets of matched pins and cups, even if they are
really hokey looking. The indentations can be found in the plumbing section,
under plastic pipe. Get the end caps, either in the 1/2 or 3/4 inch size. Note
that the size of pipe is the inside diameter of the pipe, not the outside, so
a 1/2 inch end cap will make decent sized cups. The 3/4 inch cap will make
really hefty sized ones.
There's a little problem with these end caps. Their insides are more
cylindrical than they are cup shaped, and the cups they make won't be
hemispherical. The bottom edges can be filled in a bit with some epoxy glue.
Start with a little, so it doesn't run. When it hardens, add another layer.
Keep adding layers until the inside is rounded.
The pin portion can be hammered from a piece of copper pipe about 3 inches or
so long. If you got a 1/2 inch pipe cap, get a piece of 1/2 inch pipe. Clamp a
1/2 inch steel bar into a vise, slide the pipe down over it. The bar should
leave enough empty pipe above it so that you can hammer the copper into a
curved top. If you can get a ball bearing that will fit into the pipe, so much
the better. Hammer the pipe gently, turning it around the bar as you hammer
it. Don't try to form the pipe too fast, or you'll crack the pipe, and you'll
have to cut the end off and start over. Since it's possible to knock fragments
loose, you should wear safety glasses while you do this. Hammer inward, rather
than downward, as much as you can. The downward hammering will smoosh the
copper downward and outward, causing the outside diameter to increase. We
don't want this. You don't have to hammer the pipe until the top is completely
closed. You can leave a hole about 1/4 inch wide and it won't hurt anything.
Practice this out with 1/2 inch pipe. It's much harder to form 3/4 inch pipe
without cracking it, but it can be done. Once you've got the end formed
properly, the pipe will have expanded enough that it will no longer fit into
the pipe cap. Take the bar out of the vise, set it and the pipe flat on an
anvil, or the anvil-end of the vise, and roll it while hammering it. Keep
checking the fit of the pipe into the cap until it fits easily.
Congratulations! You've just made a forming pin.
Now to make some cherry bomb cups. Cut out three 3 inch squares of kraft paper
and soak them in water. Form one tightly over the forming pin and drop a glob
of white glue over the top. Put the second wet sheet on top, smear it all
around to cover the one side with glue, and form it tightly over the first.
Repeat this with another drop of glue and the third sheet. Now, take some
heavy cord and wrap it around the paper to hold it in place. Set it aside to
dry overnight. If you were careful enough not to get any glue on the outside,
you should be able to unwrap the string when its dry. Then, trim the cup with
a small pair of scissors. You now have one completed outside cup.
The inside cup is a little trickier. Here, you also start with three soaking
wet sheets of kraft paper. Stuff the first into the indentation. Wipe some
glue over one side of the second wet sheet and stuff it in on top of the
first. Then do the same glue-and-stuff caper with the third sheet. Press all
three sheets in tightly again, and set it overnight to dry. When dry, trim
this cup as well. Exactly how much to trim will be obvious when you have one
of each. The two cups should fit together snugly to form a crude ball.
Smash paper over Stuff paper into
the forming pin the forming cup \
/ \
/ ________ _____ _____ <--
---> / \ \ / | <-- fuse
/ ____ \ ____ \_/ ____ |
/ / \ \ | | | | _|_
| | | | | | / | \ <-- inner cup
| | | \___/ | | | |
| | | | ||..|..|| <-- outer cup
| | |_______________| | ..|.. |
\_____/ powder is inside
Outer Cup Fixture Inner Cup Fixture Assembled Cups
If all of this seems an awful lot of work, remember, I did say that it was
easier and worthwhile to buy the ready made cups. But all of this does work,
so if you want to increase your experience in pyrotechnic fabrications, give
it a try. To tell the truth, there's nothing that these cherry bombs can do
that a tube salute cannot, and with lots less work. But cherry bombs seem to
have some mystique that give them everlasting popularity.
Oriental Salutes
There's another way to make very effective salutes, one that's totally
different from the standard tube salute we see in The States. The cost of the
materials is lower than what we've discussed, but they take a lot of time.
This makes them the choice in poor countries, where labor is cheap. Since
salutes are banned in the United States, these oriental items aren't imported.
The usual salutes are the quickly made tube type that are made in clandestine
factories right here in the good ol' U S of A, and most people have never seen
these hard little pear-shaped oddities.
Unlike tube salutes, which must have mostly empty space and use a supercharged
flash powder, these items are packed solid and contain low grade flash powder
and ordinary gunpowder. Here is a crude cross section.
----
/----\- Oriental Salute
//++++\-\-
//+ -- +\\-\- +++ = flash powder
||++/**\-\\\\\\ *** = gunpowder
||++|================== === = fuse
|| +\**/-////// Paper is represented by all of the following:
\\+ -- +//-/- // -- || \\
\\++++/-/-
\----/-
----
As you can see (??) the salute is made of a central ball of gunpowder
surrounded by an outer shell of flash powder. The gunpowder is enclosed in a
tissue shell to keep it from mixing with the flash powder. The fuse is coated
heavily with paper so that it will burn through the layer of flash powder
***WITHOUT*** igniting it. The fuse only ignites the gunpowder in the center.
This produces a burst of hot gas that quickly ignites all the flash powder.
While the American salutes rely on extra fine aluminum dust and a
considerable air space inside the salute to get the powder to flash all at
once, the oriental device uses a gunpowder ball, almost like a primer, to
rapidly ignite the flash powder that uses much coarser powdered aluminum.
While this takes effort to make, it can be used by those who don't have
access to aluminum dust, but can file down an aluminum block with a fine
file.
Start with a 3 inch length of green fuse. Last time we discussed the higher
degree of side spit produced by red fuse, and that has a greater chance of
igniting the flash powder on its way to igniting the gunpowder. This gives a
salute with less reliability. Use green fuse if you have it.
Place a pinch of FFFF grain plack powder in the center of a 3/4" square of
tissue paper. Use wrapping tissue, as opposed to the flimsier facial tissue.
Dip the fuse into the powder and fold the tissue up into a ball at the end of
the fuse. Twist the tissue ends and apply a little glue to attatch it to the
fuse. When dry, wrap 2 or 3 layers of masking tape around the fuse where it
meets the ball. This will shield the flash powder from the burning fuse. Now
that we've attatched a tiny ball on the fuse, we'll do it again with a larger
one. The dimensions can vary as we have some choice as to how large a bang we
want to make. Lets start with a tissue square about 4 inches square. Into
this we dump about 3 grams of flash powder made of
Potassium Perchlorate - 4 parts
Sulfir - 1 part
Bright Aluminum Powder - 1 part
The bright aluminum powder is much easier to find in chemical supply catalogs
and can also be made by filing an aluminum block with a fine file. There's no
need for aluminum dust here. Fold the tissue up around the gunpowder ball,
bringing the corners of the tissue up onto the fuse, wrapping it around the
fuse and securing it with a drop of glue. You should now have a ball of flash
powder with a tiny gunpowder ball inside, to which the fuse extends. This
ball has to be wrapped with two or three layers of dry newspaper strips,
about 1/2 inch wide. Wrap them around the bottom and attatch them to the
fuse with a twist and a drop of glue.
The dry paper is to keep the flash powder dry when we wrap it all with
similar strips of kraft paper soaked in paste. Once again, wrap it around the
bottom and twist it around the fuse. The paper should really be dripping wet
with paste. While attatching the dry paper is tricky, doing it with the wet
stuff is downright frustrating, until you've had some practice. It would be a
good idea to try this first with tissue, sand, and wire until you get the
technique down. You'll probably want to attatch 3 to 5 layers of the glue
soaked paper. If you choose to use a larger tissue square and more
flashpowder, you'll get better results by adding additional layers.
If you want to get decorative, you can get colored model airplane tissue from
a good sized hobby shop. Wrap this on as a final layer. The layers of paper
wrapped around the fuse will change the shape of the salute from a cherry to
more like a pear. This is to be expected. Leave the finished salute in a dry,
warm (not hot!) place for a couple of days. After drying, if made properly,
the casing will be hard and sound like a piece of wood when knocked on a hard
surface.
Whistles
These little curiosities are fun to make, but tend to be tricky. Unless
they're made just right they'll just make a lot of fire and smoke. The
chemicals must be very well mixed, the tube has to have the proper
dimensions, and even the smoothness of the inside of the tube will make a
difference.
Sound is simply the result of rapid back and forth changes in air pressure.
Burning pyrotechnic mixtures certainly create pressure. If we can produce a
device whose burning rate changes rapidly, it will produce sound. The trick
is not only to get it to change, but to change at speeds that will produce
tones that we can hear. If a mixture burns deep down inside a tube, and the
gas can't escape as fast as it's produced, the pressure inside will increase.
If the mixture's burning rate is very sensitive to the pressure it's under,
we might have the makings of a whistle composition. Since we might not expect
that such properties are common, we won't be surprised if we need some rather
unusual chemicals to make whistles.
It turns out that many aromatic compounds (molecules with benzene rings in
them, for you chemistry nuts) will work. Unfortunately, many such compounds
are liquid at room temperature, and even the solids tend to evaporate. Many
that do work have other problems.
If you have access to some of the outdated pyrotechnic texts, you'll see
whistle mixtures that use Potassium Picrate. This stuff is extremely sensitive
to shock and should never be used. The fact that it has to be homemade from
the even more sensitive Picric Acid is thoroughly scary.
Even the old texts mention the danger of Picrate whistles, and suggest a
"safer" composition of Potassium Chlorate and Gallic Acid. Last time we
discussed how a Chlorate can ignite spontaneously in the presence of an acid,
and we won't use this either. We won't even mention the proper proportions
needed, though we will say that old texts seem to have gotten copied from
other old texts and somewhere along the line, someone accidentally reversed
the proportions. As a result, many, but not all of the old texts have the
proportions swapped. It's just as well. Fewer people will have gotten hurt
from this mixture if they tried it, it didn't whistle, and they gave up
making it.
The modern whistle formulation consists of
Potassium Perchlorate - 7 parts
Sodium Salicylate - 3 parts
This is far safer than any of the other formulations, and happens to be
cheaper, too. For once, everything worked out in our favor!
Whistles need some special care. While some variation is allowed, it's
suggested that you follow these instructions to the letter. There are so many
different little things that can be done wrong that it can be hard to find the
problem if you're not familiar with what's required. It's best to exactly
follow a set of instructions that work, and once you've got that down you can
make small changes, one at a time.
The inside of the tube should be as smooth as possible. In fact, commercial
whistle tubes are often made of plastic to get the smoothness. In the orient,
they use bamboo tubes, which work best. But even if we lack a consistent
bamboo supply, and don't have some special plastic that resists softening
while containing a flaming mass of chemicals, we can still make do with
carefully rolled paper tubes. Shopping bag kraft paper tends to be fairly
rough. See if you can find a supply of kraft paper on a roll. Commercial rolls
come 3 or 4 feet long and quite thick. It's often used for wrapping packages
and the like. You won't want to buy it by the roll, but you may be able to
find a business that uses it for wrapping that may be talked into selling you
a dozen or so feet of it. If you can get some, roll it carefully, and try to
keep it from getting any bends that would mar its surface. Alternately, some
stores use paper bags made of a very thin, very smooth kraft paper. These
aren't supermarket-style bags, though. Check various clothing stores and
others that use the type of bag that opens by bulging out at the middle,
rather than unfolding into a box shape. If the paper has been bleached and
dyed pink or blue, the whistle won't mind.
Papermaking machines operate by pressing a slush of wood pulp between two
surfaces. One is a felt-like material, and the other is a fine wire mesh. The
difference between the surfaces gives paper two different surface finishes
from side to side. Sometimes this is more obvious than others. On some kraft
paper, one side will be smoother. If so, just keep the smoother side pointed
to the inside surface of the tube. Since you want smoothness, wrap the paper
around a 1/2 inch diameter metal or plastic rod, rather than a wooden dowel.
Don't glue it yet. Wrap at least 4 or 5 layers around the rod and then twist
the rod so that the paper is wound as tightly as possible. Now, set it on a
flat smooth surface and unroll it as far as you can go without letting the end
on the inside come unravelled. Apply a line of glue along the juncture where
the flat portion of the paper meets the rolled part, and start rolling it up
again, pressing the roll into the flat surface.
Keep adding glue where it becomes thin and keep rolling. Make sure that none
of the glue runs out the ends of the roll, or it will make it difficult or
impossible to remove the tube. If your supply of the smooth paper is small,
stop after applying 4 or 5 layers and build it up the rest of the way with the
cruder grade of kraft paper. The tube should be rolled until the wall is at
least 1/8 inch thick. If you're just learning, it would be better to roll it
up to 1/4 inch thick. The reasons will become clear later.
When the tube is rolled to the proper thickness, cut off the ends that don't
have sufficient glue, remove it from the rod, and let it dry thoroughly. The
paper should have been of sufficient size that when the scrap ends are cut
off, the tube is 4 or 5 inches long.
We haven't discussed chemical mixing much yet, except for the motorized
milling for gunpowder, and that's a special case. Many pyrotechnic mixtures
have to be thoroughly mixed to work well, and it's not possible to tell the
difference by looking at the mixed powder. In his book "Pyrotechnics", George
Weingart discusses the use of fine screens for mixing chemicals. This isn't
talking about window screens; they just won't do. Many metal dealers offer
metal meshes that almost might be considered coarse metal cloth. Finely
powdered chemicals can be mixed by slowly swirling them in a soft plastic
container and then repeatedly pressing them through these mesh screens. These
screens can mix the chemicals exceptionally well.
One thing Weingart mentions is that one should avoid letting their fingernails
strike the screen, as that can create a spark and cause a fire or explosion.
While it seems amazing that anyone would want to push flammable or explosive
chemicals through a screen with their bare hands, it does bring up another
concern. While we avoid metal tools wherever possible, there might be a
circumstance where a metal tool might accidentally fall on a screen, causing a
spark. In these modern times, it's possible to get brass mesh screens, and
brass doesn't spark when it's struck.
Now, back to mixing chemicals. Powder each ingredient separately until it
resembles flour or confectioner's sugar. Combine the ingredients in a soft
plastic container and swirl it slowly to crudely mix them. Then press them at
least 5 or 6 times through a 100 mesh screen. Brass is the material of choice,
for reasons already mentioned. Once mixed, it's time to load the tube.
There's a problem when loading the tube. We've made all sorts of efforts to
keep the inside of the tube smooth, and now we're going to go dumping in
chemicals and scraping it with a ramrod. We can't eliminate this problem, but
we can minimize it. We know that we need a long empty space in front of the
whistle tube. It's possible to fill the front end of the tube with a dowel and
load it from the back end. This will at least keep one end clean.
Get a block of wood and drill a 1/2 inch hole into it. The hole needs to be at
a good, right angle, so drill the hole with a drill press, not a hand drill.
Glue a 1/2 inch dowel pin into the hole so that it sticks out about one and a
half inches. With the glue dried and the dowel extending squarely from the
block, you can slide a whistle tube down on the dowel and proceed to load the
tube.
The block and tube is loaded from behind a heavy barrier, to protect you from
an explosion, in case the whistle explodes while loading. This is not a
frivolous extra. While an explosion of this material is unlikely, you can
never completely trust chemical mixtures. Every now and then, you can get
surprised, and the trick is to make sure that the surprises aren't harmful. A
good barrier is made from two pieces of steel plate welded or bolted firmly
together at right angles. This is another tool that the pyrotechnic
practitioner uses a great deal. The steel barrier is attatched firmly to a
workbench in such a way that you will stand inside the "V" area that it makes.
|
| /<--- Edge of workbench
You |/
stand |
here /|
/ |
/ |
_________|<--- Steel Barrier
/
/ O <-- Casing being loaded
The barrier should be made such that another plate can be attatched
horizontally on top. We won't need it for these tiny whistles, but it's
important for some larger casings that get loaded by ramming, like skyrockets.
The horizontal plate will have a hole through which you load the fuel and
insert the rammer. These whistles are small enough that you can position
yourself where the "V" portion alone can protect you. But don't try to load
the casing without it. Remember, if you're standing at a workbench, the casing
being loaded will be mere inches from your balls. If that won't persuade you
to be careful, nothing will, and maybe the removal of your "stupid genes" from
the gene pool will be a benefit to humanity.
You'll want to wear a heavy face shield and protective gloves while ramming.
Ear protection, the things that look like large earphones, aren't a bad idea,
either. As a ramrod, you'll want another 1/2 inch dowel, 1 foot long, but this
one should be sanded a bit so that it fits loosely down the tube. This will
keep the smooth insides from getting rubbed and scraped as you load the
whistle composition. Load the composition, moistened just slightly with
alcohol, about 1/2 teaspoon at a time, and ram it by hand. The safety rules
that come with these files caution you from ramming any mixture. This is good
general advice and it should be followed. However, there are a few cases where
it can be gotten around. The mixtures must be moistened and relatively
insensitive to shock. They must also be loaded from behind the aforementioned
barrier, so that even if anything does go wrong, you'll just end up with
ringing ears and a desire to go out and get yourself sloshed. Now that we've
discussed the barrier and the rules of ramming, we can ammend our safety rule,
but only very slightly.
Don't hit the rammer with anything and don't ram it really hard. While you ram
the casing, you should be standing back so that you can't actually see it,
your view blocked by the barrier. The only part of you that will be exposed to
a possible explosion will be your heavily gloved hands, and they'll be at the
end of a foot long dowel. If you don't ram straight into the tube, or you ram
too hard, the tube will be cocked sideways, and the whistle will probably be
ruined. Since you won't be looking directly at it, this will take some
practice. For this reason, you might want to make your first whistle casings
twice as thick, so that they will be a bit more forgiving of your errors as
you learn. If you're going to make a lot of these, you might consider
building a wooden fixture that will guide the rammer straight into the tube.
Note that if there is an explosion, the dowel may be fired from the tube like
a bullet from a gun, so hold it in such a way that it will not be driven into
your hand. Also, make sure that it's not "aimed" at anything that you don't
want trashed.
Guiding in the ramrod will be nearly impossible for the last inch or so, so
stop there. Cut a 1/2 inch plug off of a 1/2 inch dowel and slide it down the
tube until it rests gently against the powder. Then drip a bit of glue into
the tube, turning it so that it glues the casing to the dowel all the way
around, and set it aside to dry. Don't set it on its side. Keep it pointing
straight up so that the glue doesn't run. Now, to get the proper performance
out of this thing, the alcohol must dry completely. This means setting it
aside for a week or two before proceeding further.
Now we have to hook a fuse onto this thing. It's easier said than done. Once
again, we'll want to use green fuse instead of red, because of its reduced
side spit. Since side spit will gunk up the smooth inside surface of the tube
with residue, green fuse will be more likely to produce a working whistle. The
need for an open tube keeps us from having any good solid surface to attatch
the fuse to, and so if we had somehow imbedded it in the powder, any wiggling
of the fuse would have broken up the nicely packed powder. Any pressing of the
fuse into the powder can cause cracks and keep the whistle from working. There
are two ways of attatching a fuse. Neither is very good.
The easy way, which might be best for beginners, is to bend a length of fuse
over double, and stick one end in the tube, contacting the powder, and the
other end outside the tube, held in place with a ring of tape wrapped around
the tube and the fuse. The advantages are that its easy to do, and any
external bumping on the fuse will be absorbed by the tape, and little shock
will be transmitted into the powder, where it might shake some loose. The
disadvantages are, it burns in direct contact with the inside surface of the
tube, roughing up the surface, once it burns past the tape, the fuse is no
longer held against the powder, but can fall loose. On top of this, the end is
open to the air, so all sorts of crud can settle inside if it sits around for
a while. Glue a thin paper cover over the hole if you use this method.
The second method is to glue a single layer tube of wrapping paper over the
tube that extends about an inch and a half beyond the open mouth of the tube.
When this is dry, insert a length of green fuse that's just long enough to
reach the top of this new paper tube. The fuse should touch the powder at the
line where it meets the wall of the casing. Bunch the wrapping paper tube up
against the fuse, and apply a little glue where the paper touches the fuse.
Now, pulling the paper foreward, twist it as tightly as is practical around
the fuse without causing it to move and rub against the powder, and slip a
lose knot of string over the twist and pull it tight. Apply a dab of glue on
the string and let it dry. By pulling the paper foreward before attatching it
tightly to the fuse, you cause it to pull the fuse inward against the powder.
Even when the fuse burns through the paper, some tension will be retained.
This gives a greater chance that the whistle will be ignited. It also covers
over the open mouth of the tube and only touches the inside surface of the
tube at the point where it touches off the powder. The disadvantages are that
it takes longer to make, and that any bump into the fuse will cause it to
crumble the powder. This second method is preferable if you are careful in
handling your whistles. Since you presumably have complete control of your
whistles from workbench to firing, you can store and move them with the needed
care.
As has been said, the powder has to burn from inside a tube to make an audible
sound. As the powder burns deeper inside, the length of the open tube
effectively increases. This increased length changes the speed with which the
burning chemicals oscillate (it slows them down) causing the frequency to to
start out high pitched gradually dropping down to a very low frequency. This
is the reason for the distinctive sound of whistles and the reason you never
hear one going in the other direction. It also sets a limit on how long a
whistle can be, since they will tend to be uninteresting if they drop below
the range of human hearing.
Whistling Rockets
The strict requirements on making a working whistle and the need for an open
tube would seem to make it impossible to put it in a rocket engine and get a
whistle. Yet whistling rockets are available. The larger skyrockets tend to
have a whistle tube attatched to the outside of the rocket, and both the
engine and whistle get ignited simultaneously by a branch in the fuse. The
tiny whistling rockets use a clever way of getting a rocket-like action out of
an open tube.
/\
/ \
/----\
|****|
|****|<---Whistle tube with
|****| nose cone and fins
|****|
/|===\|\
/ |===\| \
/ |===\| \
/ |===\| \
|____|===\|____|
===\
===\\
Solid plug--> === \\ <--Fuse
attatched to === \
support base ===
=============
If we were to stuff a loose plug down the whistle tube with a hole just large
enough to admit the fuse, then when the whistle composition ignited, the
pressure would would fire the plug from the tube like cork is forced from a
champagne bottle. If we take a whistle tube with only a limited amount of
composition in it, attatch a nosecone and fins, and stuff a stationary plug up
the whistle tube, then when the composition is ignited, the whistle tube would
blow itself up off the plug into the air. The reason for the limited amount of
whistle composition is for weight considerations. Only the initial burst of
gas will fire the whistle tube into the air, and any extra composition will
just weigh it down. The trick is for it to stay in the air while it's
whistling. A whistling rocket that pops into the air and then lands on the
ground while still whistling will be regarded by spectators as a "dud".
Commercial whistling rockets tend to use plastic tubes, and use inside
diameters only 1/4 to 3/8 inch. There's usually only about a 1/4 inch depth of
fuel inside.
Some of the tiny whistling rockets end with a report. Since a regular
firecracker would add too much weight, the usual report is made by adding a
chemical that detonates, exploding without a casing. If the nosecone end of
the whistle tube has a small hole in it before its loaded, then a small amount
of whistle composition will be visible through it. A small wad of Lead Azide
can be placed into this hole so that it will be ignited and explode when the
whistle composition is just burning out. The Lead Azide can be kept from
crumbling off by hiding it under the nosecone. Preparation of Lead Azide is
described in part 2 of this series.
Stay tuned for part 6, where we'll talk more about fireworks that require
special construction. Have fun but keep it safe!

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