How Do Safety Matches Work

Theres a lot of interesting chemistry going on in the small head of a safety match.  Safety matches are safe because they dont undergo spontaneous combustion and because they dont make people sick. You have to strike a safety match against a special surface in order to get it to ignite. In contrast, early matches relied on white phosphorus, which is unstable and likely to burst into flame in air. The other downside to using white phosphorus is its toxicity. Before safety matches were invented, people became ill from chemical exposure. Key Takeaways Safety matches are considered safe in contrast to an older match formulation that contained white phosphorus. White phosphorus matches would ignite spontaneously and were highly toxic.A safety match uses friction to generate the heat needed to initiate combustion. The match head contains powdered sand or glass for this purpose.While safety matches contain red phosphorus instead of white phosphorus, the element is converted to white phosphorus vapor. Thus, inhaling the fumes from matches isnt exactly healthy. The match heads of safety matches contain sulfur (sometimes antimony III sulfide) and oxidizing agents (usually potassium chlorate), with powdered glass, colorants, fillers, and a binder made of glue and starch. The striking surface consists of powdered glass or silica (sand), red phosphorus, binder, and filler. When you strike a safety match, the glass-on-glass friction generates heat, converting a small amount of red phosphorus to white phosphorus vapor.White phosphorus spontaneously ignites, decomposing potassium chlorate and liberating oxygen.At this point, the sulfur starts to burn, which ignites the wood of the match. The match head is coated with paraffin wax so the flame burns into the stick.The wood of a match is special, too. Match sticks are soaked in an ammonium phosphate solution that reduces afterglow when the flame goes out. Match heads are commonly red. This isnt the natural color of the chemicals. Instead, red dye is added to the tip of the match to indicate its the end that catches on fire. Sources Carlisle, Rodney (2004). Scientific American Inventions and Discoveries. New Jersey: John Wiley Sons. p. 275. ISBN 0-471-24410-4.Crass, M. F., Jr. (1941). A history of the match industry. Part 1. Journal of Chemical Education. 18 (3): 116–120. doi:10.1021/ed018p116