Formula: nitrated cellulose, mixture of compounds
Description: Nitrocellulose is used as a binder in pyrotechnic compositions. It is also used in some items without any other oxidisers or fuels. In other fields of pyrotechnics than fireworks it is widely used as a propellant, sometimes mixed with nitroglycerine and other materials (so called double- or triple base propellants).
Hazards: Nitrocellulose can detonate in large quantities. It is also extremely flammable and must be handled as if it is a mixed composition (which it is in fact, on the molecular level, unlike most pure chemicals). Pure nitrocellulose is thermally instable and will decompose over time. Double and triple base powders contain nitroglycerine and are probably best avoided for use in fireworks.
Sources: Nitrocellulose is sold in gun shops to those with the proper licences in some countries. Double and triple base powders seem to be most common though. A less nitrated but usable form of cellulose, called celluloid, is also used in some household items: ping-pong balls. This may be a source for small amounts. Celluloid is also used for film but that is getting a little scarce these days with digital cameras taking over the market. It is probably too expensive for pyro uses anyway. Finally, it is possible to make nitrocellulose at home. The procedure is too lengthy to describe well here, but it involves treating cellulose (preferably cotton or paper) with a mixture of sulfuric acid, nitric acid and water. The product is then washed extensively and stabilised. Properly stabilising the product at home may be difficult and commercial nitrocellulose is preferred for that reason.
Potassium benzoate
Formula: KC7H5O2
Description: Potassium benzoate is commonly used in whistle compositions. It is a white powder
Hazards: Potassium benzoate is not particularly dangerous.
Sources: Potassium benzoate can be prepared from benzoic acid and potassium carbonate or hydroxide. Benzoic acid is not very soluble, but both potassium carbonate and hydroxide are. Dissolve 140.2g potassium carbonate or 56.1g potassium carbonate in 250 ml water, and add 146g benzoic acid. Bring the mixture to a boil. If potassium carbonate is used, CO2 gas will evolve. Continue boiling untill all benzoic acid has dissolved, occasionally adding some water to make up for what has evaporated. When all benzoic acid has dissolved, continue boiling untill the first crystals of potassium benzoate are observed (ie the saturation point has been reached). Then allow the solution to cool to room temperature. Potassium benzoate will crystalise in needle shaped crystals. Filter, and rinse the crystals twice with ice-cold water. The crystals may be dried in an oven at 100 deg C.
Potassium chlorate
Formula: KClO3
Description: Potassium chlorate is a very common oxidiser in pyrotechnics, even though it has some treacherous properties and other oxidisers would sometimes be safer to use. Part of the reason of its popularity in commercial pyrotechnics is that it is cheap and easily available. The large scale production of this compound made the first quality colored fireworks possible, about a century ago.
Hazards: Potassium chlorate is toxic, and breathing protection should be worn when handling fine powder. Compositions made with potassium chlorate tend to be more sensitive than those based on nitrates and perchlorates and should therefore be handled accordingly. Potassium chlorate, or any chlorate for that matter, should never be used in combination with sulfur and sulfides. Mixtures containing both are very sensitive and may spontaneously ignite. In general, when using chlorates great care should be taken to avoid contamination of other compositions or tools. Also read the general safety <safety_EN.html> page for more information on this problem.
Sources: Potassium chlorate can be prepared at home. For this purpose, sodium chlorate <cheminfo_EN.html> is prepared first by electrolysis. It may also be obtained as a herbicide in some countries (France, for example) Then, by double decomposition with potassium chloride, potassium chlorate is prepared from this solution. The product is recrystallised, dried and powdered.
Potassium perchlorate
Formula: KClO4
Description: Potassium perchlorate is a very common oxidiser in pyrotechnics. Composition based on perchlorates tend to be less sensitive than those based on chlorates, and perchlorates can be used with sulfur and sulfides. For these reasons potassium perchlorate is much preferred above chlorates. Drawback is its slightly higher price.
Hazards: Potassium perchlorate is toxic, and breathing protection should be worn when handling fine powder.
Sources: Potassium perchlorate can be prepared at home. For this purpose, sodium perchlorate <cheminfo_EN.html> is prepared first by electrolysis. Then, by double decomposition with potassium chloride, potassium perchlorate is prepared from this solution. The product is recrystallised, dried and powdered.
Sodium chlorate
Formula: NaClO3
Description: Sodium chlorate is hardly ever used in pyrotechnics, since it is very hygroscopic. It finds occasional use in composite rocket propellants. It is however very usefull as a starting point in the preparation of several other (less hygroscopic) chlorates for which reason it is included here.
Hazards: Sodium chlorate is toxic, and breathing protection should be worn when handling fine powder. Compositions made with sodium chlorate tend to be more sensitive than those based on nitrates and perchlorates and should therefore be handled accordingly. Sodium chlorate, or any chlorate for that matter, should never be used in combination with sulfur and sulfides. Mixtures containing both are very sensitive and may spontaneously ignite. In general, when using chlorates great care should be taken to avoid contamination of other compositions or tools. Also read the general safety <safety_EN.html> page for more information on this problem. Acidic solutions containing chlorates generate a very poisonous and explosive gas, ClO2.
Sources:Sodium chlorate can be prepared at home. It involves electrolysing a sodium chloride solution under certain circumstances. A description of the process, cell and anode design, etc. for home produciton may be found in the chlorate and perchlorate <kclox_EN.html> section of this page. In some countries, France for example, sodium chlorate may be obtained as a herbicide.