Every material has an ‘autoignition point’ – the temperature at which it will spontaneously ignite without any external source of ignition. With wood, the autoignition point is 300ºC. As soon as wood is heated to this temperature, it starts to release hydrocarbons. These then react with the oxygen in the air and ignite the wood. By comparison: cotton can withstand much higher heats. A cotton shirt has an autoignition point of 407ºC. Diesel, on the other hand, will ignite at a temperature of just 210ºC.