Torrefying wood is still little known in Quebec. This heat treatment at high temperature gives a natural material of exceptional beauty and can replace chemically treated wood frequently used for decks and siding. This is a new ecological trend. Indeed, torrefied wood has several characteristics. It is waterproof, rot-restistant and contains no chemicals.
These sidings have been treated at high temperatures for several hours in the absence of air in an autoclave without the addition of chemical. Wood, when heated under pressure, is as resistant to decay than the chemically treated wood or the red cedar.
The wood is subjected to a gradual increase in temperature in a sealed furnace until it reaches 0% humidity (about 20 hours to a temperature ranging from 130 to 180 ° C, according to manufacturers). The temperature is then raised to give the final color to the wood. The process lasts from 8 to 12 hours at a temperature of 200 to 220 ° C, according to the manufacturer, type of wood and finish desired. Thereafter, the wood is moistened in order to restore flexibility and ease of handling.
When wood is subjected to a very high temperature, much of the hemicellulose and lignin is destroyed, reducing the nutrient offered to fungi and insects. Roasting gives the wood a dark color, reduces the possibility of water absorption and makes the wood less vulnerable to adverse weather and moisture. The guarantees are up to 60 years on the product.
The roasting process gives the wood a color from caramel to chocolate, to all material, both in surface and depth. Since wood fades when exposed to UV rays, sanding of the surface allows you to retrieve the initial color. To prevent the wood to fade under the influence of UV rays, it can be coated, usually an opaque or semi-opaque dye. Several species can be roasted. Since the process does not use any chemicals, wood roasted can be recovered for energy production or incinerated at the end of life.