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Comment by jazzyjackson

5 hours ago

> if left untreated, is known for spontaneously combusting as it decays and oxidizes.

Does anyone remember the 90s when as a laymen it seemed like an open debate whether humans would occasionally combust spontaneously? I guess it stopped happening once falling asleep with a cigarette lost popularity

But my point is I wasn’t aware that “spontaneous combustion” was a real thing one has to worry about it. Linseed oil rags will do this too, and that’s why patent leather shoes are coated in plastic now instead.

This can happen to mulch as well if it's left in a very big pile for a long time.

  • If you have a big enough pile of organic matter, exothermic decomposition can lead to fire, if the conditions are right.

    Commonly happens in grain silos, mulch piles, etc.

    It really doesn't take that large of a pile of grass clippings or wood chips to get some steam coming out and a lot of steam if you disturb the pile.

    • Yep, many hay barns have caught fire because the hay was bailed while too wet and it is fermenting so vigorously.

HowStuffWorks used to be full of expert animations of automatic transmissions and helicopters around 2006 but they had a multipart article on spontaneous combustion, with anecdotes of 1890s people who retained too much ethanol.

Human spontaneous combustion is a silly myth. Other kinds like oily rags and apparently fishmeal are very real.

  • Grain dust and flour also come to mind. Essentially anything with the appropriate fuel/air mixture can combust, often explosively, even if we otherwise think of it as food!

    • Those events aren't spontaneous combustion, an ignition source is needed to cause a dust explosion with flour, grain, or sawdust. Spontaneous combustion of something like linseed oil happens with no external ignition source. Spontaneously combustible substances undergo exothermic reactions in normal conditions, e.g. when drying, curing, being exposed to air, or similar. They have low enough flash points that their own heat is enough to cause ignition, which is why you never hear about concrete spontaneously combusting despite having an exothermic curing process.

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