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8. Commonly Used Chemicals in Pyrotechnics: P




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This article is from the Pyrotechnics FAQ, by Hans Josef Wagemueller zoz@cs.adelaide.edu.au with numerous contributions by others.

8. Commonly Used Chemicals in Pyrotechnics: P

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.

 

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