Exploding Pants

By CodingStrategies on February 8th, 2019

In March 2017, a lawyer in a Miami, Florida courtroom prepared to deliver closing arguments in an arson case. According to newspaper reports, he was about to make the case that his client did not intentionally set his car on fire, but that the car spontaneously combusted (as cars are inclined to do). As the attorney fiddled with some item in his pants pocket, smoke began rising from that area and the lawyer was observed dashingfrom the courtroom. After the jury was removed, the lawyer returned and blamed the faulty battery in an e-cigarette for the episode that left him with a singed suit. His client was subsequently convicted of second-degree arson.

But what if pants do more than catch on fire?

In 1931, the peace and quiet of the rural New Zealand countryside was destroyed by a terrifying series of events. Suddenly, and seemingly at random, men’s trousers began to explode. Some detonated on the wash line, some while drying in front of the fire, and others while being worn! What started as an isolated incident or two, soon gripped the nation in an epidemic of exploding pants.

Farmers expect a lot from their clothing. In general, farming is rugged, often dirty work that challenges the strength and durability of all regularly worn garments. But that doesn’t usually mean that their slacks will randomly burst into flames. Richard Buckley was one of the lucky ones; when his trousers combusted he wasn’t wearing them. As reported by the Hawera Star on August 12, 1931: “While Mr. Richard Buckley’s trousers were drying before the fire recently, they exploded with a loud report. Although partially stunned by the force of the explosion, he had sufficient presence of mind to seize the garments and hurl them from the house, where they smoldered on the lawn with a series of minor detonations.”

To understand this phenomenon, it is first important to recognize the nature of local flora called ragwort (Jacobaea vulgaris), also known as benweed, staggerwort, cankerwort and “Stinking Willie.” Ragwort is a particular problem in cattle pastures, because cattle avoid eating this poisonous plant, which allows the ragwort to spread unchecked. Because it is classified as a noxious weed in New Zealand, farmers expend significant time and resources trying to control it. In 1931, the method of choicewas the application of sodium chlorate.

Sodium chlorate is an inorganic compound, generally available as a crystalline powder that is soluble in water. Sodium chlorate was used as a non-selective herbicide and was considered poisonous to all green plants. It could be applied to non-crop land for spot treatment, or for total vegetation control on areas such as roadsides, fences and ditches. As dairy farming became more widespread in New Zealand, more pasture space was required for cattle and the war on ragwort began in earnest. As a result, the government encouraged farmers to spray down affected areas with a sodium chlorate solution. And, sure enough, the ragwort began to perish.

With a significant side effect: sodium chlorate is highly caustic when dry, a fact that came to light as the farmers’ pants began to combust and detonate. Richard Buckley’s exploding trousers were one of the first examples of the properties of drying sodium chlorate, but he was definitely not the last. After wearing his pants to spray the herbicide, Richard hung them in front of the fire to dry out.  As the saturated clothing dried, the water was removed, leaving the combustible sodium chlorate crystals on the natural fibers of the garments (generally wool or cotton). In essence, this created an explosive cloth that could be set off by friction, heat, flames or a strong impact (ICD-10-CM code X06.2XXA, Exposure to ignition of other clothing and apparel, initial encounter).

According to the National Institutes of Health, the peculiar case of Richard Buckley’s exploding trousers was among the subjects that inspired the 2005 Ig Nobel prize winners. The “Igs” are awarded for science that "first makes you laugh, then makes you think," and "cannot and should not be reproduced." Ragwort remains a noxious, malevolent weed spread across New Zealand. A number of subsequent attempts have been made to control the plant and increase grazing land, including the use of other herbicides and the introduction of biological controls such as the cinnabar moth and ragwort flea beetle. While these treatment methods have met with some success, unless strictly controlled, ragwort will continue to proliferate, reduce available grazing land and potentially poison unsuspecting livestock.