Formula: NH4 NO3
Description: Ammonium nitrate is an oxidiser. It is very hygroscopic and therefore not used very often in fireworks. It finds some use in composite propellants, but performance is not as good as perchlorate based propellants.
Hazards: Large masses of ammonium nitrate have been known to explode on some occasions although it is very unsensitive. Smaller quantities are less likely to detonate. The risk of detonation increases when ammonium nitrate is molten or mixed with fuels such as metal powders or organic substances. Ammonium nitrate should never be mixed with chlorates as this may result in ammonium chlorate formation, possibly leading to spontaneous ignition. Mixtures of metal powders and ammonium nitrate are likely to heat up spontaneously and may ignite, especially when moist. This can sometimes be prevented by the addition of small amounts of boric acid (1 to 2%), but in general it is better to avoid these mixtures at all. The hygroscopic nature of ammonium nitrates makes this problem worse (also see aluminum).
Sources: Ammonium chloride solution can be prepared by neutralising ammonia solution with nitric acid. It is advised to use a slight excess of ammonia. That is to make sure no remaining acid will be present in the ammonium nitrate obtained on evaporation and crystallisation. Otherwise traces of the acid solution may be enclosed in the crystals, possibly leading to spontaneous ignition of mixtures made with it. Large quantities of ammonium nitrate can also be cheaply bought as fertilizer. In the Netherlands a fertilizer called 'kalkammonsalpeter' is sold. This consists of ammonium nitrate mixed with 'mergel', a mineral consisting mainly of calcium carbonate. The ammonium nitrate can be extracted with water.
Ammonium perchlorate
Formula: NH4ClO4
Description: Ammonium perchlorate is an oxidiser used in a large number of compositions. Very impressive color compositions can be made with it, but their burn rate is often too low for use in star compositions. For lancework and torches slow burning is an advantage and it is therefore commonly used in these items. Ammonium perchlorate is also used in composite rocket propellants, including the propellants used in the solid propellant boosters used for the space shuttle. The decomposition products of ammonium perchlorate are all gasses which is very beneficial for rocket propellants.
Hazards: Ammonium perchlorate can detonate by itself, although it is not very sensitive. Larger amounts and mixtures of ammonium perchlorate with metal powders or organic substances are more likely to detonate.
Sources: Ammonium perchlorate is usually bought from chemical suppliers and from dedicated pyro suppliers such as skylighter <http://www.skylighter.com/>. Fine ammonium perchlorate powder is a regulated substance in most countries and cannot easily be bought or transported. Since it is such a usefull chemical in pyrotechnics it can be worth the time and effort to try to prepare it at home. This can be done by first making sodium perchlorate <cheminfo_EN.html> followed by double decomposition with ammonium chloride (other ammonium compounds can be used). The preparation of sodium perchlorate is most easily accomplished by electrolysis, the procedure for which is described elsewhere on this page.
Barium carbonate
Formula: BaCO3
Description: Barium carbonate is used both in white and green color compositions. When chlorine donors are present in a composition a green color will result from the formation of BaCl+ in the flame. Without chlorine donors BaO will be formed which emits white light. Barium carbonate is convenient to use in chlorate based color compositions since it will neutralize residual acid which reduces the risk of spontaneous ignition.
Hazards: Most barium compounds are very poisonous, especially the more soluble barium compounds such as the chlorate and nitrate. A dust mask should be worn at all times when working with barium carbonate.
Sources: Barium carbonate is cheaply available in kilogram quantities from ceramic supply shops. However, this material is often contaminated with small amounts of barium sulfide which are left over from the production process. Therefore, ceramics grade barium carbonate should never be used in mixtures incompatible with sulfides such as chlorate based mixtures. Barium carbonate is not easily made at home.
Barium chlorate
Formula: BaClO3
Description: Barium chlorate is used as an oxidiser in green color compositions. Fierce burning and high color purity compositions can be made with it.
Hazards: Barium chlorate is poisonous and a dust mask should be worn at all times when handling it. Barium chlorate should never be mixed with sulfur or sulfides or allowed to come in contact with mixtures containg sulfur or sulfides since this could result in spontaneous ignition. (Sulfur reacts with water and air to form small amounts of sulfuric acid. Sulfuric acid and chlorates react producing ClO2, an explosive gas which will ignite many organic materials on contact). Mixtures made with barium chlorate are often especially sensitive to friction and shock (even more so than potassium chlorate based mixtures) and should be handled with extra care.
Sources: Barium chlorate is usually purchased from chemical suppliers and from dedicated pyro suppliers such as skylighter <http://www.skylighter.com/>. It can be made at home from sodium chlorate <cheminfo_EN.html> and barium chloride by double decomposition. Barium chlorate can also be prepared from barium chloride by electrolysis in a process analogous to that used for preparing sodium chlorate.