Our forefathers knew an extremely simple and natural way of giving wood lasting protection from outside influences – heat treatment, with no chemical additives! It works like this: heat the wood to between 180-220° C, and a kind of ‘caramelization’ takes place, producing a dark brown coloration. Parts of the (hemicellulose) cell walls are broken up and ejected in crystal form, and the hollow spaces left behind filled up by the remaining elements. This process stops the wood absorbing water, so it no longer swells when exposed to damp and also loses its tendency to warp and split. Thermowood is therefore an ideal material for things that often get wet.