Exploding trousers

In New Zealand in the 1930s, farmers reportedly had trouble with exploding trousers as a result of attempts to control ragwort, an agricultural weed.

Farmers had been spraying sodium chlorate, a government recommended weedkiller, onto the ragwort, and some of the spray had ended up on their clothes. Sodium chlorate is a strong oxidizing agent, and reacted with the organic fibres (i.e. the wool and the cotton) of the clothes. Reports had farmers' trousers variously smoldering and bursting into flame, particularly when exposed to heat or naked flames. One report had trousers that were hanging on a washing line starting to smoke. There were also several reports of trousers exploding while farmers were wearing them, causing severe burns.

The history was written up by James Watson of Massey University in a widely reported article, "The Significance of Mr. Richard Buckley's Exploding Trousers", and which later won him an Ig Nobel Prize

In their May 2006 "Exploding Pants" episode the popular U.S. television show MythBusters investigated the idea that trousers could explode based on the events of New Zealand in the 1930s. Experimenters tested four substances on 100% cotton overalls:

Each of these were put to four different ignition methods: flame, radiant heat, friction and impact. Although not naming "the herbicide" as sodium chlorate, they confirmed that trousers would indeed vigorously combust due to flame, radiant heat and impact, though their friction tests did not cause ignition. However, combustion (i.e. an exothermic chemical reaction between a fuel and an oxidant) is not the same as an explosion, which involves a rapid increase in volume accompanied by the release of energy in an extreme manner (i.e. a shock wave). Even so, a person witnessing such an event (especially if he or she were wearing the trousers) would likely describe such a sudden event as an explosion.

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