This is a very interesting botany sh*tpost about accidental cloth-related combustion. It starts with a story about linseed oil, which in woodworking is rubbed on furniture as a varnish. Linseed oil has an exothermic chemical reaction with oxygen, meaning that the reaction creates heat. This can of course cause some inconvenient spontaneous combustion…
Hay will spontaneously combust as well in hot conditions, many farmers have lost barns and livestock to this.
it’s not due to hot conditions, it’s due to the inner core of the hay bales being damp, leading to decomposition. Decomposition creates heat, and if there is nowhere for the heat to go it can build up to the point the hay catches fire