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Archive-name: pyrotechnics-faq
See reader questions & answers on this topic! - Help others by sharing your knowledge
REC.PYROTECHNICS FAQ
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Last Updated 28JUL95
CONTENTS
========
1. Introduction - Welcome to rec.pyrotechnics
2. Reading rec.pyrotechnics
3. Posting to rec.pyrotechnics
4. Legal Aspects of Pyrotechnics
5. PGI - Pyrotechnics Guild International
6. Pyrotechnic Literature
6a. Fireworks Literature
6b. Fringe Literature
6c. Net-Available Information
7. Frequently Asked Questions
7a. Nitrogen Tri-Iodide, NH3.NI3
7b. Thermite
7c. Dry Ice Bombs
7d. Smoke Bombs
7e. Basic Pyrotechnic Devices
7f. Terminator Bombs, MacGyver, etc.
7g. Match Rockets
8. Commonly Used Chemicals in Pyrotechnics
1. Introduction - Welcome to rec.pyrotechnics
=============================================
Rec.pyrotechnics is a worldwide newsgroup dedicated to the discussion of
fireworks and explosives, mostly concerned with their construction. The
readers of rec.pyrotechnics welcome anyone with an interest in the
subject, be they experienced or just trying to get started in the hobby.
If you are just getting started, try to get hold of as much information
on the subject as you can, and read it carefully. If it is explosives
you are interested in, make sure you read up on the theory behind
explosives. There is a lot of misinformation in movies etc. regarding
explosives, so it is important you get a good background from a reliable
source.
In the Pyrotechnic Literature section below are several books that are
must-reads for anyone serious about pyrotechnics. Try all your local
libraries - even if they don't have the books mentioned below, they are
sure to have some information on the subject. Remember, you can never be
too well-informed - it is *your* safety that is at stake, and not being
aware of all the aspects involved is extremely dangerous.
Pyrotechnics and explosives are not safe - factories have been destroyed
in the past, and they have access to the best materials and equipment,
and take the most stringent safety precautions. Some people on the net
have also been injured by accidents, and many of them had years of
experience and took extremely comprehensive safety measures.
Some knowledge of chemistry and physics is essential - if you didn't do
high-school chemistry, get yourself a chemistry textbook and read it.
Make sure you understand the basic principles involved for any
composition you might be making. It is a good idea to check a recipe out
with someone who is experienced in chemistry, to make sure you haven't
missed any safety aspect.
If you take the time to find out all the information, and put safety of
yourself and others as your highest priority, you will find pyrotechnics
an extremely fun and rewarding hobby.
2. Reading rec.pyrotechnics
===========================
Often you will see an interesting composition or method posted to
rec.pyrotechnics and the temptation is to run out and try it immediately.
However, sometimes information posted will contain errors, or omit
important safety aspects. Sometimes people will post methods that they
heard from some vague source, or that they think should work but haven't
tried.
Leave it for a couple of days to see if anyone on the net responds to it.
If not, get a printout of it and read it several times to make sure you
are completely familiar with it. If you have any questions or corrections
for an article, please don't hesitate to post. People on the net would
much rather answer a question that may seem "silly" to you, than to have
you get hurt.
Also, a complete archive of rec.pyrotechnics is available on the server
news.armory.com in its original message format. You can therefore do a
search on past articles there and quite probably find the information
you are looking for without needing to ask again. To read the archives,
first set your news host by setting the NNTPSERVER environment variable
to news.armory.com - this is achieved on Unix machines by typing:
setenv NNTPSERVER news.armory.com
You may then start your newsreader in the usual way. Note however that
to resume reading news from your local server you must quit the newsreader
and reset the NNTPSERVER variable.
3. Posting to rec.pyrotechnics
==============================
If you have a composition or a method that has served you well, please
share it with the net. Also if you have a question, people will be happy
to help you out with it.
However, please remember that you message is going to be read by a lot of
people around the world, many of whom may not be as familiar with aspects
of your posting as you are. Include all relevant safety information, for
example possible mixing and storage hazards, toxicity, expected behaviour
of the composition once ignited etc. Also, it is worth keeping in mind
that the relevant legal authorities do read rec.pyrotechnics and other
newsgroups.
If you post something you haven't tried, be sure to make that clear in
your article. This is a good idea when asking questions as well - make
sure it is obvious that you are asking a question, rather than posting
something you don't know about and hoping someone will correct it.
Read through your article before posting it to make sure that you have
covered every aspect, and that there are no errors or ambiguities that
could cause people to interpret part of it the wrong way.
4. Legal Aspects of Pyrotechnics
================================
Chances are that many of the procedures involved in pyrotechnics are
illegal without a permit where you live. There are generally separate
laws regarding storage of chemicals, manufacture of fireworks,
manufacture of explosives, storage of fireworks, storage of explosives,
use of fireworks and use of explosives.
The laws regarding fireworks may also be split up in terms of the "Class"
of fireworks concerned - commonly available fireworks are Class C, while
the fireworks typically seen at displays will be mainly Class B, with
some Class C. Make sure you know where you stand in terms of the law in
your area, and get a permit if necessary.
Make sure that what you are doing will not cause any damage to other
people's property, and that there are no innocent bystanders that can get
hurt. There are plenty of laws relating to injury or damage to third
parties and their property, not to mention lawsuits. We don't want anyone
to get in trouble with the law because of anything here.
5. PGI - Pyrotechnics Guild International
=========================================
Pyrotechnics Guild International, Inc is a non-profit organization of
professional and amateur fireworks enthusiasts: builders, shooters &
watchers.
Membership includes a quarterly journal and an annual convention.
(New Castle, Pennsylvania, '94)
(Stevens Point, Wisconsin, '95)
For membership information, contact:
PGI
Ed Vanasek
18021 Baseline Ave
Jordan, MN
55352
You need either three recommendations from random people or one
recommendation from a PGI member. Dues are $25/yr., US.
Another newsletter is American Fireworks News, monthly, miscellaneous news,
technical articles, ads, $19.95/yr.
AFN
Star Rt Box 30
Dingmans Ferry, PA
18328
6. Pyrotechnic Literature
=========================
6a. Fireworks Literature
------------------------
These are extremely good books on the subject of pyrotechnics, and are
really a must-read for the serious pyrotechnics enthusiast. Many others
that are not listed here are also worth reading - check out your local
library, Books In Print, Pyrotechnica Publications etc. for more
references.
Conkling, John A.: "Chemistry of Pyrotechnics: Basic Principles & Theory"
(Marcel Dekker, New York, NY 1986. (ISBN 0-8247-7443-4).)
See also Conkling's articles in Scientific American (July 1990, pp96-102)
and Chemical & Engineering News (June 29, 1981, pp24-32).
Shimizu, Takeo: "Fireworks - The Art, Science and Technique", 2nd ed.
(Pyrotechnica Publications, 1988. (ISBN 0-929388-04-6).)
Lancaster, Ronald: "Fireworks, Principles and Practice" (Illus.) 2nd ed.
(Chemical Publishing Company Incorporated, 1992. (ISBN 0-8206-0339-2).)
The 1st edition is also available, and is much cheaper. The 2nd edition
only has about 20 new pages and some minor corrections, but is about
$50 more expensive.
Shimizu often directs people to Lancaster rather than giving the detailed
information himself.
Weingart, George W.: "Pyrotechnics" (Illus.)
(Chemical Publishing Company Incorporated, 1968. (ISBN 0-8206-0112-8).)
Davis, Tenney L.: "Chemistry of Powder and Explosives"
More references are available from Books In Print.
By far the best sources for all books on fireworks are:
Quantum Tech Publications
208 Franklin Blvd
Mahomet, IL 61853
(217) 586-5999
Pyrotechnica Publications
2302 Tower Drive
Austin, TX 78703 USA
6b. Fringe Literature
---------------------
These books usually deal with home-made explosives etc. more than
fireworks, and are usually dubious at best. Most are not worth buying,
especially if you are more interested in the pyrotechnics field.
Much of the information in them is inherently unsafe - many of the books
deal with field-expedient methods, and assume that some casualties are
acceptable along the way. If you want to try anything out of one of
these, it is a good idea to ask about it on the net or to someone
experienced in pyrotechnics or explosives.
"The Anarchist's Cookbook": this is in "Books in Print" so your local
bookstore should be able to get you a copy. Alternatively, you can send
$22 (includes postage) to Barricade Books, PO Box 1401, Secaucus NJ 07096.
The Anarchist's Cookbook gets a big thumbs down because it is full of
inaccurate information.
"Ragnar's Guide to Home and Recreational Use of High Explosives": thumbs
down as it is even more inaccurate than The Anarchist's Cookbook.
US Army Technical Manual 31-210 1969 "Improvised Munitions Handbook":
The Improvised Munitions Handbook generally gets okay reviews; it
contains a whole bunch of recipes for making explosives etc. out of handy
chemicals. You can get it from several sources, gun shows, or for $5 from
Sierra Supply.
"Poor Man's James Bond Vol. 2": mostly a set of reprints of various
books, in small type. It does have Davis' Chem. of Powder and Explosives
and what appears to be Vol. 1 and 2 of the Improvised Munitions Handbook
series. Vol. 1 of PMJB has a reprint of Weingart's book Pyrotechnics (?)
Here are some sources for the books. Most of these places will send you
a catalog with related material.
Loompanics, P.O. Box 1197 Port Townsend, WA 98368.
This company sells a wide selection of fringe books on drugs, explosives,
war, survival, etc.
Catalog $5.
Sierra Supply, PO Box 1390 Durango, CO 81302 (303)-259-1822.
Sierra sells a bunch of army surplus stuff, including technical
manuals such as the Improvised Munitions Handbook.
Sierra has a $10 minimum order + $4 postage. Catalog $1.
Paladin Press, P.O. Box 1307 Boulder, CO 80306
Delta Press Ltd, P.O. Box 1625 Dept. 893 El Dorado, AR 71731
Phoenix Systems, P.O. Box 3339, Evergreen CO 80439
Phoenix carries fuse (50 ft/$9), smoke grenades, tracer ammo, dummy
grenades. Catalog $3.
U.S. Cavalry, 2855 Centennial Ave. Radcliff, KY 40160-9000 (502)351-1164
Sells all kinds of military and adventure equipment.
Thanks to Ken Shirriff, Phil Ngai, Keith Wheeler, Charles Marshall, Gary
Hughes, and others.
6c. Net-Available Information
-----------------------------
Articles from rec.pyrotechnics and other miscellaneous
pyrotechnic text files are available by anonymous FTP from
paradox1.denver.colorado.edu in the directory
Anonymous:Text-files:Pyrotechnics: .
The so-called "gopher files", a collection of 4 introductory files on
pyrotechnics, are available using a file transfer client called gopher.
The sources for gopher are available via anonymous FTP from
boombox.micro.umn.edu in the directory /pub/gopher/ .
You can see what it looks like by telneting to consultant.micro.umn.edu
and logging in as "gopher". The pyroguide is in the Gopher system under:
Other Gopher and Information Servers/Fun & Games/Recipes/Misc/Pyrotechnics
These files are quite a good introduction to pyrotechnics, including
information on the manufacture of fuses and casings.
"The Big Book Of Mischief", commonly abbreviated TBBOM, is available
via anonymous FTP from ftp.std.com, and has the file path:
obi/Mischief/tbbom13.txt (version 1.3, 1991)
obi/Mischief/tbbom15.txt (version 1.5, 1994)
It can also be obtained through e-mail from dr@ripco.com
This is generally a compilation of articles from many sources such as
'The Poor Man's James Bond' and from here in rec.pyrotechnics. This also
comes under the heading of 'Fringe Literature', as many of the items and
methods contained in it are of dubious safety and reliability.
7. Frequently Asked Questions
=============================
Below are descriptions of several things that are frequently asked about
on rec.pyrotechnics - they are not generally of much use in fireworks,
but they are here to cut down message traffic on these subjects which
have been covered many times before.
First though, here are some safety rules. Read these and memorize them.
1. Mix only small batches, especially when trying something out for the
first time. Some mixtures, particularly flash powder, will detonate
rather than deflagrate (just burn) if enough is present to be self-
confining. It doesn't take much to do this. Small amounts of
unconfined pyrotechnic mixtures may damage your hands, eyes or face.
Larger amounts can threaten arms, legs and life. The hazards are
greatly reduced by using smaller amounts. Also be aware that a mixture
using finer powders will generally behave MUCH more vigorously than
the same mixture made with coarser ingredients. Many of these mixtures
are MUCH more powerful than comparable amounts of black powder. Black
powder is among the tamest of the pyrotechnician's mixtures.
2. Many of these mixtures are corrosive, many are very toxic, some will
react strongly with nearly any metal to form much more unstable
compounds. Of the toxics, nearly all organic nitrates have *very*
potent vasodilator (heart and circulatory system) effects. Doses for
heart patients are typically in the small milligram range. Some can
be absorbed through the skin.
3. Keep your work area clean and tidy. Dispose of any spilled chemicals
immediately. Don't leave open containers of chemicals on your table,
since accidental spillage or mixing may occur. Use only clean equipment.
4. If chemicals need to be ground, grind them separately, never together.
Thoroughly wash and clean equipment before grinding another chemical.
5. Mixing should be done outdoors, away from flammable structures, and
where ventilation is good. Chemicals should not be mixed in metal or
glass containers to prevent a shrapnel hazard. Wooden containers are
best, to avoid static. Always use a wooden implement for stirring.
Powdered mixtures may be mixed by placing them on a sheet of paper and
rolling them across the sheet by lifting the sides and corners one at
a time.
6. Don't store powdered mixtures, in general. If a mixture is to be
stored, keep it away from heat sources, in cardboard or plastic
containers. Keep all chemicals away from children or pets.
7. Be sure all stoppers or caps, especially screw tops, are thoroughly
clean. Traces of mixture caught between the cap and the container can
be ignited by friction from opening or closing the container.
8. Always wear a face shield, or at least shatterproof safety glasses.
Also wear a dust mask when handling powdered chemicals. Particulate
matter in the lungs can cause severe respiratory problems later in
life. Wear gloves and a lab apron when handling chemicals. This rule
is very important.
9. Make sure there are no ignition sources near where you are working.
This includes heaters, motors and stove pilot lights. Above all,
DON'T SMOKE!
10. Have a source of water READILY available. A fire extinguisher is
best, a bucket of water is the bare minimum.
11. Never, under any circumstances, use metal or glass casings for
fireworks. Metal and glass shrapnel can travel a long way, through
body parts that you'd rather they didn't.
12. Always be thoroughly familiar with the chemicals you are using. Don't
just rely on the information provided with the recipe. Look for extra
information - the Merck Index is very good for this, especially
regarding toxicity. It can also provide pointers to journal articles
about the chemical.
13. Wash up carefully after handling chemicals. Don't forget to wash your
ears and your nose.
14. If a device you build fails to work, leave it alone for half an hour,
then bury it. Commercial stuff can be soaked in water for 30 minutes
after being left for 30, then after 24 hours cautious disassembly can
be a valid learning experience. People have found "duds" from shoots
that took place over a year ago, having been exposed to rain etc,
which STILL functioned when fitted with fresh fuse or disposed of in
a bonfire. Even after a 30 minute waiting period (minimum), initial
pickup should be with a long- handled shovel.
15. Treat all chemicals and mixtures with respect. Don't drop them or
handle them roughly. Treat everything as if it may be friction- or
shock-sensitive. Always expect an accident and prepare accordingly,
even if all these safety precautions are observed. Several people on
the net have gotten stitches, lost fingers, or been severely burned.
Some of them were very scrupulous in their safety precautions and had
many years' safe experience with pyrotechnics.
7a. Nitrogen Tri-Iodide, NI3.NH3
--------------------------------
Nitrogen Tri-Iodide is a very unstable compound that decomposes
explosively with the slightest provocation. It is too unstable to have
any practical uses, but is often made for its novelty value. Some books
describe uses for it in practical jokes etc. but in my experience it has
been far too unstable for this to be a feasible idea. Despite its common
name, the explosive compound is actually a complex between nitrogen
tri-iodide and ammonia, NI3.NH3 (nitrogen tri-iodide monoammine).
Reagents:
Solid Iodine (I2)
Ammonia solution (NH4OH) - Use only pure, clear ammonia. Other solutions,
such as supermarket 'cloudy' ammonia, will not
give the desired product.
Place a few fine crystals of iodine in a filter paper. The best way to
make fine iodine crystals is to dissolve the iodine in a small quantity
of hot methanol (care: methanol is toxic and flammable. Heat on a steam
bath away from open flame. Use in a well-ventilated area.), and then pour
the solution into a container of ice-cold water. This will cause
extremely fine iodine crystals to precipitate out. Drain off the liquid
and wash the crystals with cold water. If this method is not possible,
crush the iodine as finely as possible.
Then filter ammonia through the iodine crystals. Use a small amount of
ammonia and refilter it, to reduce wastage. The smaller the pieces of
iodine the better the result, as more iodine will react if it has a
greater surface area. You will be able to recognise the NI3.NH3 by its
black colour, as opposed to the metallic purple of the iodine.
Reaction: 3I + 5NH OH ---> 3NH I + NI .NH + 5H O
2(s) 4 (aq) 4 (aq) 3 3(s) 2 (l)
When the NI3.NH3 decomposes it will leave brown or purple iodine stains.
These are difficult to remove normally, but can be removed with sodium
thiosulphate solution (photographic hypo). They will fade with time as
the iodine sublimes.
Safety aspects:
NI3.NH3: Despite the common misconception presented in many articles
on NI3.NH3, it is NOT safe when wet. I have personally witnessed
NI3.NH3 exploding while at the bottom of a 1000Ml plastic beaker
full of water. NI3.NH3 can not be relied on not to decompose at
any time. Even the action of air wafting past it can set it off.
If you want to dispose of some NI3.NH3 once you have made it, it
can be reacted safely with sodium hydroxide solution. NI3.NH3 is
a potent high explosive, and should be treated with respect. Its
power, instability and unpredictability require that only small
batches be made. Do not make more than you can immediately use.
Never attempt to store NI3.NH3.
The detonation of NI3.NH3 releases iodine as a purple mist or
vapour. This is toxic, so avoid breathing it. Toxicity data on
NI3.NH3 is unknown, but I think it is safe to assume that eating
or touching it would be a bad idea anyway.
Iodine: Iodine sublimes easily at room temperature and is toxic -
ingestion of 2-4g of iodine can be fatal. Make sure you are in a
well-ventilated area, and avoid touching the iodine directly.
Ammonia: Again, use in a well-ventilated area as ammonia is not
particularly pleasant to inhale. Ammonia is corrosive, so avoid
skin contact, especially if using relatively concentrated
solution. If skin contact occurs, wash off with water. Don't
drink it.
7b. Thermite
------------
The thermite reaction is a redox reaction that produces a lot of heat and
light. In its usual configuration, temperatures can exceed 3000 degrees C,
and molten iron is produced. It is therefore mainly used for welding, and
by the Army in incendiary grenades.
There are many possible configurations - basically it is the reaction
between a reactive metal and the oxide of a less reactive metal. The most
common is as follows:
Aluminium powder, Al (coarse) 1 volume part or 3 weight parts
Iron (III) Oxide, Fe203 1 volume part or 1 weight part
A stoichiometric mixture will provide best results.
The powders are mixed together and ignited with a suitable fuse. Many
people use magnesium ribbon - I don't recommend this, as magnesium ribbon
is not all that easy to light, and quite prone to going out due to oxygen
starvation. A much better fuse for thermite is a common sparkler. The
mixture should be shielded with aluminium foil or similar to prevent
sparks from the sparkler igniting the thermite prematurely.
Reaction: 2Al + Fe O ---> Al O + 2Fe + lots of heat
(s) 2 3(s) 2 3(s) (l)
The mixture can be varied easily, as long as the metal oxide you are
using is of a less reactive metal than the elemental one you are using,
e.g. copper oxide and zinc. Adjust the ratios accordingly.
Safety aspects:
Reaction: Make sure you no longer need whatever you are igniting the
thermite on - the reaction will melt and/or ignite just about
anything. If you ignite the thermite on the ground, make sure
the ground is DRY and free of flammable material. If the ground
is wet a burst of steam may occur, scattering 3000 degree metal
everywhere.
Be careful when igniting the thermite - use adequate shielding
to prevent premature ignition. Don't get close to the mixture
once ignited - it has been known to spark and splatter. Don't
look at the reaction directly. It produces large amounts of
ultraviolet light that can damage the eyes. Use welder's
goggles, 100% UV filter sunglasses or do not look at all.
Aluminium: Chemical dust in the lungs is to be avoided. As always, wear a
dust mask. Make sure the environment you are working in is
dry - aluminium powder can be dangerous when wet. Fine
aluminium dust is pyrophoric - this means it can spontaneously
ignite in air. For this reason aluminium powder with a large
particle size is recommended.
Iron Oxide: This is not directly toxic, but any particulate matter in the
lungs is not good. Again, the dust mask is important.
7c. Dry Ice Bombs
-----------------
Dry ice bombs are devices that use pressure to burst a container,
producing a loud report and limited shock effects. No chemical reaction
is involved - the container, usually a plastic 2-litre soft drink bottle,
is burst by the physical reaction of solid carbon dioxide, CO2, subliming
into gas. As the CO2 sublimes, the pressure builds up and eventually the
container ruptures.
The method is very simple - some dry ice is added to the container, some
water is added (about 1/3-1/4 full) and the cap is screwed on tight.
Within a short time the container will burst, usually extremely loudly.
The water can be omitted if a longer delay time is required. It is
reported that these devices can be manufactured using liquid nitrogen
instead of dry ice, and no water. This is not recommended as the delay
time will be substantially shorter.
Safety aspects:
Device: NEVER use glass or metal containers! I cannot stress this enough.
Dry ice bombs are extremely unpredictable as to when they will go
off, and a glass or metal container is very very dangerous to
both the constructor and anyone else in the vicinity. Plastic
bottles are much safer because the fragments slow down quicker,
and thus have a smaller danger radius around the device. Plastic
fragments are still very nasty though - don't treat the device
with any less caution just because it is made of plastic.
There is no way to tell how long you have until the dry ice bomb
explodes - it can be anywhere from a few seconds to half an hour.
Never add the water or screw the cap on the container until you
are at the site you want to use it and you are ready to get away.
Never go near a dry ice bomb after it has been capped. If a dry
ice bomb fails to go off, puncture it from long range with a
slingshot, BB gun, by throwing stones at it or similar. Some
indication of timing can be achieved by semi-crushing the
container before capping - once the container has expanded back
to its original shape it is no longer safe to be anywhere near.
Don't forget that the temperature of the day and the size of the
dry ice pieces will affect the delay length - don't assume that
delay times will be similar between bombs. A hotter day or
smaller pieces of dry ice (i.e. greater surface area) will create
a shorter delay. Remember, even though no chemical reaction
occurs you can still be legally charged with constructing a bomb.
Dry Ice: Humans will suffocate in an atmosphere with a carbon dioxide
concentration of 10% or more. Use in a well-ventilated area. Dry ice
typically has a temperature of about -75 degrees C, so do not
allow it to come into contact with the skin, as freezer burns
and frostbite will occur. Always use gloves or tongs when
handling dry ice.
7d. Smoke Bombs
---------------
A relatively cheap and simple smoke mixture is potassium nitrate
(saltpetre) and sugar. The mixture can be used in powder form, but much
better results are achieved by melting the components together. The
mixture should be heated slowly until it just melts - beware of excessive
heating as the mixture will ignite. Keep a bucket of water next to you in
case the mixture does ignite, and peform the entire operation outdoors if
possible.
The mixture does not have to be completely liquid, the point at which it
has about the viscosity of tar or cold honey is about right. While it is
semi-liquid it can be poured into cardboard or clay molds, and a fuse
inserted. Once it cools and hardens it will be similar to a stick of hard
candy, hence its common name of "caramel candy".
Safety aspects:
Mixture: The mixture burns very hot. Don't go near it once ignited, and
don't assume that whatever the mixture is contained in or
standing on will survive. Try not to breathe the smoke as fine
particles in the lungs are not good for them.
7e. Basic Pyrotechnic Devices
-----------------------------
Stars
-----
A star is an amount of pyrotechnic composition that has by some means
been fashioned into a solid object. These are the bright burning objects
you see ejected from Roman candles, shells, mines etc.
Usually the pyrotechnic composition is mixed with a binder and a small
amount of solvent to make a doughy mass which is then fashioned into
stars, although some use has been made of so-called pressed stars, which
involve the composition being pressed extremely hard into a mold with a
hydraulic press or similar, thus doing without the solvent.
The usual methods are to make the composition into a flat pancake or
sausage and cut it up into stars ("cut stars"), pushing it through a tube
with a dowel, cutting it off at regular intervals ("pumped stars") or
rolling cores of lead shot coated in fire clay in a bowl of the
composition ("rolled stars").
Cutting and pumping produce cubic or cylindrical stars, while rolling
produces spherical stars. Pumped stars are the most suitable for Roman
candles, because it is easy to get the correct width. The stars are often
dusted with a primer, usually meal black powder, to ensure ignition.
Shell
-----
The shell is a sphere or cylinder of papier mache or plastic which
contains stars and a bursting charge, together with a fuse. It is fired
into the air from a tube using a lift charge, usually black powder. The
time the fuse takes determines the height above the ground at which the
shell will burst, igniting and spreading the stars.
Rocket
------
A rocket consists of a tube of rocket fuel, sealed at one end, with a
constriction, or nozzle, at the other end. The burning fuel produces
exhaust gases, which, when forced out the nozzle, produce thrust, moving
the rocket in the other direction.
Solid fuel rockets can be one of two types - end-burning, where the fuel
is solidly packed into the tube, so the fuel can only burn at one end -
and core-burning, where there is a central core longitudinally through
the fuel, so the fuel can burn down its full length. At the top of the
rocket can be a smoke composition, so it is possible to determine the
maximum height ("apogee") of the rocket, or a burst charge and stars.
Lance
-----
A lance is a thin paper tube containing a pyrotechnic composition. These
are most commonly used in large numbers to make writing and pictures at
fireworks shows - this is referred to as lancework. The tube is thin so
burns completely away as the lance burns, so as not to restrict light
emission from the burning section.
Gerb
----
These are pyrotechnic sprays, often referred to as fountains or flower-
pots. They consist of a tube full of composition, sealed at one end and
with a nozzle at the other, similar to a rocket. Unlike a rocket, they
are not designed to move anywhere, so all the emphasis is on making the
nozzle exhaust as long as pretty as possible, with large amounts of
sparks, nice colours etc.
The sparks are produced by metal powders or coarse charcoal in the gerb
composition, with coarse titanium powder being the chemical of choice.
Gerb compositions in a thin tube set up in a spiral arrangement are used
as wheel drivers, for spinning fireworks e.g. Catherine wheels.
Waterfall
---------
These are similar to gerbs, but usually do not spray as far. They are
usually mounted horizontally in banks of several tubes, placed some
distance above the ground. When ignited, the effect is like a brilliant
waterfall of sparks.
Mine
----
These have a mortar arrangement similar to that for a shell, but are not
designed to send out a shell. The lift charge sends up a bag full of
stars and a bursting charge, with a short fuse set to spread the stars
relatively close to the ground. Because the bag has much less strength
than a shell, the stars are not spread as far, and the final effect is
that of a shower of stars moving upward in an inverted cone formation.
7f. Terminator Bombs, MacGyver, etc.
------------------------------------
The first thing to remember when watching pyrotechnics in movies, TV
shows etc. is that it is exactly that, not real life. There is almost
always no point in trying to extrapolate what MacGyver, for example,
does back to reality, with respect to pyrotechnics at least. Reese
making those bombs from supermarket supplies in Terminator was bogus,
as are pretty much any information on explosives you receive from
movies. Sorry.
7g. Match Rockets
-----------------
How To Build A Match Rocket
Version 1.5
7/14/95 [Slightly edited for FAQ 28JUL95]
Brett K. Carver
brett@sr.hp.com
Disclaimer: Please notice that the title is not "How To Build THE Match
Rocket". This describes how I built match rockets and represents
only one method of construction. Others will have different/better
ideas. This should be enough to get one started.
Warning: Improper construction of match rockets can cause them to explode
KILLING YOU INSTANTLY; Improper firing of match rockets can cause
them to penetrate your body KILLING YOU INSTANTLY. (well, probably
not, but be careful anyway).
Definition: Basically, a match rocket is a paper match with something
wrapped over the match-head to form a combustion chamber and
focus the flow of escaping gas. The match is then heated until
it ignites and the escaping gases cause it to take off.
Parts: You'll need the following:
a book of paper matches
aluminum foil
cellophane tape (i.e. Scotch tape)
two sewing needles
scissors
Constructions: This roughly how I built them...
1. Remove a match from the book. Trim off the end to remove the
frayed edges from where it was ripped out.
2. Use about 1 square inch of foil and 'wrap' it around the head
of the match extending between 1/4 and 1/2 inch past the head.
I left 'wrap' vague since there a many ways to do it. The
goals are to: a) keep weight down, b) get several layers of
foil around the match head, and c) keep things neat and clean.
3. [optional] I had a lot of trouble with blow-out (the force of
combustion tearing a hole in the foil), so I started wrapping
the foil with a few layers of cellophane tape. It seemed to
solve my blow-out problems without adding as much weight as
additional foil did.
4. Add two exhaust ports, one down each side of the match. This
can be done two ways: a) after step #3, push a sewing needle
along the match-stick, under the foil, up to the match-head, or
b) do steps #2 and #3 with the needles already in place. In
either case the important thing is to get a small well-formed
port. I used the smallest sewing needles I could find (the
head of a regular pin caused it not to lay flat creating poor
ports). In addition, I'd run my finger-nail along the side of
the needle to force the foil down so that I'd have a nice clean
tube rather than just a crude gap between the match-stick and
the foil. I use two needles because with only one I'd always
end up damaging one port while creating the other. Obviously,
remove the needles when done.
Example: What follows is ONE way to wrap the foil around the match head
(step #2 above). This is the basic method I used, but I'm sure it
can be improved:
1. Start with a one inch square piece of foil:
##########
##########
foil -> ##########
##########
##########
2. Fold in half (it's now 1" x 1/2"):
##########
foil -> ##########
##########
3. Fold in half again over the match head (it's now 1/2" x 1/2"
with the match head in the middle (the head is now covered
with a double layer of foil):
#####
foil -> #####======= <- match stick
#####
4. Sort of fold/wrap the excess foil around the match as neatly as
possible:
After wrapping one side:
foil -> #####======= <- match stick
#####
After wrapping the other side:
foil -> #####======= <- match stick
5. Move on to step #3 above (optional tape).
Firing: Put the completed rocket in a launcher. It is often suggested
that one use a bent paper-clip as a launcher. Don't waste your
time. I used a short piece of 1/4 inch copper tube mounted to a
hinge. The launch angle was adjustable by turning a screw. The
tube was short enought that the match-head just extended enough to
apply heat. The back of the tube was blocked off. Besides the
obvious ease of launch-angle adjustment, the smooth tube reduced
friction or hang-ups when firing, and the blocked off tube produced
some back-pressure that I think helped produce higher launch
velocities. Anyway, once in the launcher, aim it, and heat the
match-head until it ignites. A lighter works better than a match
for this as it takes a while for ignition and sometime the match
would burn out first.
Distances: I saved my record-breaking matches writing the distances on them.
Launches inside the house became limited by the ceiling and the far
wall. The longest inside launch I got (hitting the far wall) was:
29' 6"
Outside shots were not so limited. The longest outside launch was:
44' 8"
So, there are some target numbers to shoot for... :-)
Fine-tuning: The point of building match-rockets is not to simply 'learn
how to do it', but to get started and fine-tune the rockets to
improve distance. Construction materials, construction techniques,
launcher design, launch angle, and many other things all come into
play at getting a long-distance flight. Experiment. Have fun!
Things that didn't work: The following are things I tried that didn't
improve my flight distance.
1. Wooden matches - they were too heavy.
2. Using two or more matches - too heavy and I couldn't get a good
seal on the combustion chamber.
3. Adding extra match-heads - adding extra 'fuel' presented two
problems: a) I had trouble getting a nice tight wrap of the foil
with the extra material in there, b) if I did get a good one built,
it would 'blow-out' at launch (adding more foil just seemed to make
it too heavy). I had my best results with simple one-head rockets
so I stopped trying for more fuel.
Final caution: Don't play with matches. :-)
8. Commonly Used Chemicals in Pyrotechnics
==========================================
Ignitibility and Reactivity
---------------------------
The secret of making a good pyrotechnic mixture is _homogeneity_. The
better the contact with the oxidiser and the fuel is, the fiercer the
composition. Finely ground fuels and oxidisers are essential for good
stars and propellants. The required intimacy also implies that mixing
can never be thorough enough.
For consistent results, use the same sieves and same mixing methods. Wet
mixing is sometimes more efficient than stirring the dry composition;
moreover, it is almost always safer. Star compositions and granulated
powders can almost always be mixed with water or some other solvent.
Good, homogenous compositions also ignite more easily. Large amounts of
loose, fine powder of almost any pyrotechnic composition represent a
large fire and explosion hazard. But when such a powder is kneaded and
cut into stars or carefully pressed in a tube, it will take fire easily
and burn smoothly.
This is the pyrotechnist's dilemma: the best compositions are often the
most dangerous ones, too. But not always. There are chemicals and
compositions with much worse safety records than today's compositions
have. In the list of pyrotechnic chemicals below, the most notorious ones
have been indicated.
Aluminium, Al -- Fuel
This is used in many compositions to produce bright white sparks or a
a bright white flame. There are many grades of aluminium available
for different spark effects. Most pyrotechnic compositions that involve
sparks use aluminium, e.g. sparklers, waterfalls etc.
Ammonium Nitrate, NH4NO3 -- Oxidiser
This is used very infrequently in pyrotechnics due to its hygroscopic
nature and the fact that it decomposes even at relatively low
temperatures. Even when dry, it reacts with Al, Zn, Pb, Sb, Bi, Ni, Cu,
Ag and Cd. In the presence of moisture it reacts with Fe. It reacts with
Cu to form a brissant and sensitive compound. It is best not to use any
bronze or brass tools when working with ammonium nitrate.
Ammonium perchlorate, NH4ClO4 -- Oxidiser
Used as an oxidiser in solid rocket fuels, most notably the solid booster
rockets for the Space Shuttle. Using it in a composition improves the
production of rich blues and reds in the flames. As with any ammonium
salt, it should not be mixed with chlorates due to the possible formation
of ammonium chlorate, a powerful and unstable explosive.
Anthracene, C14H10 -- Smoke Ingredient
Used in combination with potassium perchlorate to produce black smokes.
Antimony, Sb -- Fuel
The metal is commonly used in the trade as 200-300 mesh powder. It is
mainly used with potassium nitrate and sulphur, to produce white fires.
It is also responsible in part for the glitter effect seen in some
fireworks.
Antimony trisulphide, SbS3 -- Fuel
This is used to sharpen the reports of pyrotechnic noisemakers, e.g.
salutes. It is toxic and quite messy.
Barium salts -- Colouring Agents
Used to colour fires green. several are used:
Barium carbonate, BaCO3 -- Colouring Agent, Stabilizer
As well as being a green flame-colourer, barium carbonate acts as a
neutralizer to keep potentially dangerous acid levels down in pyrotechnic
compositions.
Barium chlorate, Ba(ClO3)2.H2O -- Colouring Agent, Oxidiser
Used when deep green colours are needed. It is one of the more sensitive
chemicals which are still used, best to avoid if possible, but if used it
should be in combination with chemicals which will reduce its sensitivity.
Barium nitrate, Ba(NO3)2 -- Colouring Agent/Enhancer, Oxidiser
Not very strong green effect. Used with aluminium powder to produce
silver effects. Below 1000C aluminium burns silvery-gold, characteristic
of aluminium-gunpowder compositions. Above 1000C it burns silver, and may
be achieved using barium nitrate. Boric acid should always be used in
compositions containing barium nitrate and aluminium.
Barium oxalate, BaC2O4 -- Colouring Agent
Sometimes used, generally in specialised items with magnesium.
Boric acid, H3BO3 -- Stabilizer
This is a weak acid, often included in mixtures that are sensitive to
basic conditions, notably those containing aluminium.
Calcium carbonate, CaCO3 -- Stabilizer
Used as a neutralizer in mixtures that are sensitive to both acids and
bases, for example chlorate/aluminium flashpowder.
Calcium oxalate, CaC2O4 -- Colour Enhancer
Used to add depth to colours produced by other metal salts.
Carbon black/Lampblack, C -- Fuel
A very fine form of carbon made by incompletely burning hydrocarbon fuels.
Commonly used in gerbs to produce bright orange sparks.
Charcoal, C -- Fuel
Probably the most common fuel in firework manufacture, it is not pure
carbon and may contain in excess of 10% hydrocarbons. Indeed, the purer
carbon charcoals (e.g. activated charcoal) do not necessarily give better
results, and are very often worse than less pure grades. It is included
in the vast majority of pyrotechnic compositions in various mesh sizes
and grades, or as a component of black gunpowder.
Clay
This is an important material for making fireworks, not as a reagent but
to perform various practical applications such as blocking or constricting
the ends of tubes for crackers or rocket nozzles, or coating lead shot
prior to the application of star composition when making rolled stars.
Copper and copper compounds -- Colouring Agents
Used to add both green and blue colours to flames:
Copper metal, Cu -- Colouring Agent
Both the bronze and electrolytic forms are occasionally used, but easier
methods are available for the same effect.
Copper acetoarsenate, C4H6As6Cu4O16 -- Colouring Agent
Commonly called Paris Green, this chemical is toxic but used to produce
some of the best blue colours in combination with potassium perchlorate.
Copper carbonate, CuCO3 -- Colouring Agent
This is the best copper compound for use with ammonium perchlorate for
production of blue colours. Also used in other blue compositions.
Copper (I) chloride, CuCl -- Colouring Agent
Cuprous chloride is probably the best copper compound for creating blue
and turquoise flames, and it can be used with a variety of oxidizers.
It is non-hygroscopic and insoluble in water, but it is oxidised slowly
in air.
Copper oxides, CuO/Cu2O -- Colouring Agent
Used for many years for blues, but needed mercury chloride to intensify
colours. Seldom used.
Copper oxychloride -- Colouring Agent
Occasionally used in cheap blue compositions.
Cryolite, Na3AlF6 -- Colouring Agent
Also known as Greenland spar, this is an insoluble sodium salt. Sodium
salts are used to produce yellow colours, but as sodium salts generally
absorb water this tends to be a problem. By using cryolite this problem
is surmounted.
Dextrin -- Binder
Dextrin is a type of starch that is added to many firework mixtures to
hold the composition together. It is the most commonly used binder in
pyrotechnics.
Gallic acid (3,4,5-trihydroxybenzoic acid)
This is used in some formulas for whistling fireworks. Whistle mixes
containing gallic acid are generally the most sensitive of the whistling
fireworks, with high sensitivity to both friction and impact when used
with chlorates, but cannot be used with perchlorates either. There are
safer alternatives for whistle compositions.
Gum arabic (Gum Acacia) -- Binder
An example of the various wood-resin-based adhesives used to bind firework
compositions. Others used include Red Gum and Gum Copal.
Gunpowder
Black powder is the mainstay of pyrotechnics. At a basic level it is
a mixture of potassium nitrate, charcoal and sulphur. However, simply
mixing these ingredients together will not produce proper black powder.
It merely produces a much milder version, which itself is used
extensively in pyrotechnics, and is commonly called meal powder.
True black powder takes advantage of the extreme solubility of potassium
nitrate by mixing the very fine milled ingredients into a dough with
water, then using strong compression to force the water out of the
mixture, so that tiny crystals of potassium nitrate form in and around
the particles of the other ingredients. This produces a product that
is far fiercer than the simple meal powder.
Hexachlorobenzene, C6Cl6 -- Colour Enhancer
Used as a chlorine donor in coloured compositions that require one.
Rarely used, with PVC, Saran and Parlon being preferred.
Hexachloroethane, C2Cl6 -- Smoke Ingredient
The basic ingredient in many military smoke formulas. Not often used
with inorganic smoke mixtures, except those containing zinc.
Iron, Fe -- Fuel
The metal filings are used mainly in gerbs to produce sparks. Iron will
not keep well in firework compositions, and so it is generally pre-coated
with an oil/grease. One simple method is to add 1 gram of linseed oil to
16 grams of iron filings, mix, and boil off the excess oil.
Linseed oil -- Stabilizer
Used to coat metal powders in order to prevent them from oxidation, both
prior to use and in the firework composition. Polyesters are used in
commercial fireworks, but linseed oil remains an accessible option to the
amateur.
Lithium carbonate, Li2CO3 -- Colouring Agent
Used to colour fires red. It has no advantage over strontium salts for
the same purpose.
Magnesium, Mg -- Fuel
Used to produce brilliant white fires. Should be coated with linseed oil/
polyester resin if contained in a composition which is not to be used
immediately, as it may react with other components of the mixture. The
coarser magnesium turnings are sometimes used in fountains to produce
crackling sparks. Magnesium-aluminium alloys give similar effects, and
are rather more stable in compositions.
Parlon -- Colour Enhancer, Binder
Parlon is a chlorine donor, and a key ingredient in many coloured stars.
It is a chlorinated isoprene rubber, chlorine content 66%. It interferes
with burning less than PVC or saran, and can be used as a binder. It
is soluble in methyl ethyl ketone (MEK) and partially in acetone.
Compositions made with parlon and acetone or MEK are nearly waterproof.
Phosphorus, P -- Fuel
Phosphorus is rarely used in pyrotechnics today, except for a few
specialized applications. It was used commonly many years ago, but as the
hazards associated with its use became known it dropped out of use.
Phosphorus comes in several forms, of which the red and the white/yellow
varieties were used. Red phosphorus (used in the strikers on the side of
matchboxes) is the more stable form, while white phosphorus (used by the
military in incendiary devices) ignites spontaneously in air, and must
therefore be stored under water or otherwise protected from the
atmosphere. Both forms are toxic.
Polyvinylchloride (PVC) -- Colour Enhancer, Binder
PVC is a commonly used chlorine donor. It is not as good as Parlon for
this purpose, but is cheaper and more readily available. PVC is soluble
in tetrahydrofuran (THF) but almost all other solvents are useless.
Methyl ethyl ketone (MEK) will plasticise PVC to some extent, however.
Potassium benzoate, C6H5CO2K -- Fuel
Used in whistling fireworks, in combination with potassium perchlorate.
It must be very dry for this purpose, and should be less than 120 mesh.
Potassium chlorate, KClO3 -- Oxidiser
Originally used very commonly in pyrotechnics, potassium chlorate has
gradually been phased out due to its sensitivity, in favor of potassium
perchlorate. Mixtures containing potassium chlorate and ammonium salts,
phosphorus or anything acidic are particularly dangerous. For this reason
mixtures containing potassium chlorate and sulphur are to be avoided,
as sulphur (especially the common "flowers" of sulphur) may contain
residual amounts of acid that can sensitize the mixture. In general,
potassium chlorate should be avoided unless absolutely necessary.
Chlorates have probably caused more accidents in the industry than all
other classes of oxidisers together. The reason lies in their sensitivity
to acids and their low decomposition temperature. When mixed with an
easily ignitable fuel, such as sugar or sulfur, chlorates will ignite
from a fingernail striking a wire screen. Moreover, sulfur is often
acidic, a fact that has lead to spontaneous ignition of sulfur-chlorate
compositions. If you intend to use chlorates, pay extra attention to
safety.
Potassium nitrate, KNO3 -- Oxidiser
A very common oxidising agent in pyrotechnics, potassium nitrate is one
of the chemicals you should never be without. From its essential use
in gunpowder to general applications in most fireworks, you will find
potassium nitrate used wherever a relatively mild oxidiser is required.
In fireworks it should pass 120 mesh, but can be used at 60 mesh. The
fine powder should be used as soon as possible after grinding or
milling as it will soon cake and have to be re-ground.
Potassium perchlorate, KClO4 -- Oxidiser
More expensive than potassium chlorate, but a better oxidising agent
and far safer. In almost all mixtures that previously required the
chlorate, safety factors have led to its replacement with potassium
perchlorate. It should be used in place of the chlorate wherever possible.
Potassium picrate
This is a shock sensitive compound that is used in some whistle formulas.
While safer than gallic acid formulas in this respect, care should be
taken to keep it away from other metals such as lead, because some
other metallic picrates are extremely sensitive.
Saran -- Colour Enhancer, Binder
Saran is another plastic chlorine donor. It is most commonly encountered
in the form of the cling wrap used to protect foodstuffs. It is slightly
soluble in tetrahydrofuran (THF) and will be plasticised by methyl ethyl
ketone (MEK).
Shellac -- Binder
Shellac is an organic rosin commonly used as a binder where a water-
soluble binder would be inappropriate. It can be bought at hardware
stores in the form of lustrous orange flakes, which can be dissolved
in boiling ethanol.
Sodium salts -- Colouring Agents
Sodium salts are sometimes used in place of the corresponding potassium
salts, but this is uncommon due to their hygroscopic nature. They rapidly
absorb water from the air, which can ruin a pyrotechnic composition.
In particularly dry environments they can be used without too much
trouble, and are therefore used in places like Egypt due to the relative
cheapness of some of the salts with respect to the potassium ones. Sodium
salts are also used as colourising agents, producing a characteristic
orange flame.
Strontium salts -- Colouring Agents
Used to colour flames a brilliant red:
Strontium carbonate, SrCO3 -- Colouring Agent, Retardant
Used often for producing red colours, and as a fire retardant in
gunpowder mixtures.
Strontium oxalate, SrC2O4 -- Colouring Agent, Retardant, Stabilizer
As for strontium carbonate, generally, but suffers from greater water
content.
Strontium nitrate, Sr(NO3)2 -- Colouring Agent, Oxidiser
This is the most commonly used strontium salt, because it provides the
most superb red colour available. Best results will be acheived if the
strontium nitrate is anhydrous.
Sulphur, S -- Fuel
Another basic fuel in pyrotechnics, sulphur is used in many pyrotechnic
formulas across the range of fireworks, most obviously in black powder.
It is recommended to avoid the common "flowers" of sulphur, as they
contain residual acid. If they cannot be avoided, a small amount of a
neutralizer such as calcium carbonate should be added if acid is likely
to present a problem.
Titanium, Ti -- Fuel
The coarse powder is safer than aluminium or magnesium for producing
sparks, and gives rise to beautiful, long, forked blue/white sparks.
Fantastic for use in any spark composition, especially gerbs.
Petroleum jelly (Vaseline) -- Stabilizer
Very occasionally used to protect metal powders e.g. iron by coating them
with a thin film of petroleum jelly.
Zinc, Zn -- Fuel, Smoke Ingredient
Zinc metal is used in what are known as zinc spreader stars, which
produce a very nice effect that looks like a green glowing cloud. Also
used in several smoke formulas, due to the thick clouds of zinc oxide
that can be produced.
SPECIAL CAVEATS
---------------
AVOID:
Mixing chlorates with: acidic ingredients
sulphur or sulphides
ammonium salts
phosphorus
pitch or asphalt
gum arabic solution.
Mixing picric acid with: lead or lead compounds
almost any other metal.
Mixing ammonium nitrate with metals especially copper.
Mixing nitrates with aluminium WITHOUT boric acid.
Further Information
-------------------
Further information about these chemicals, for example chemical, physical
and toxicity data, can be obtained from the following books:
The Merck Index
The CRC Handbook of Physics and Chemistry
Ullmann's Encyclopaedia of Industrial Chemistry
Kirk-Othmer's Encyclopaedia of Chemical Technology
The information may be found elsewhere, but these are the most
comprehensive and readily available.
--*** Many thanks to Dave Pierson, Christian Brechbuehler, Ken Shirriff,
--*** Petri Pihko, Bill Nelson, Robert Herndon, Mike Moroney, Geoffrey Davis
--*** and others for their helpful comments, corrections, additions and advice.
--
______ _____________ ______________________ ______
/\####/\ / / / / /\####/\
/ \##/ \ /_______ / / _ ______ / / \##/ \
/____\/____\ / / / / \ \ / / /____\/____\
\####/\####/ / /____\ \_/ / / /_______ \####/\####/
\##/ \##/ / / / / \##/ \##/
\/____\/ /_____________________/ /____________/ \/____\/
zoz@cs.adelaide.edu.au
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