Fuming, or smoking is a wood finishing process which is used to make wooden floors darker and stress the grain pattern. This technique is often applied with respect to oak wood flooring which is treated to make it darker. It consists in exposing a wooden floor to ammonia fumes in enclosed environment. For this purpose a container, a closed tank or a sealed tent can be used to put the wood inside and introduce small amounts of ammonia in the atmosphere. By reacting with the tannins, ammonia changes the shade of wood.
Frequently, people who carry out this process themselves apply the ammonia directly onto the surface of wooden planks. However, this is not the right approach. The wood colour is changed through the reaction of the wood to the presence of ammonia in the air. As a result, tannins contained in the wood come to the surface. The closer the tannins are to the wood surface, the darker the wood will be. If you want to get a really dark hue, keep it in a container where ammonia is present inthe air for a longer time. Using this wood darkening technique you can get different grades of dark wood, starting from rich brown colour, ending with dark brown which is almost black.
In principle, the final effect depends on how long the wood is kept in the environment filled with ammonia. To get light brown colour leave the wood for only twelve hours. If you prefer the wood to get darker, leave it there for 72 hours. Moreover, the colour change also depends on the temperature – the higher it is, the faster the wood changes its colour and tone. If exposed to warmer temperatures, the wood will usually take on red tones, while lower temperatures give it green hues, which leaves a lot of room for creativity.
Probably not many of you know that someone came across this technique by pure accident. Fuming was discovered in horse stables at the end of the 20 Century, when someone discovered that the beams that were above the horses were darker, while those in other parts of the stable were lighter. This was caused by ammonia contained in the horses’ urine. Since that time fuming has become a very popular wood treatment process among furniture makers and has been widely used to add floors a special dark appeal. This technique isn't anything difficult, but it's recommended to let professionals take care of it, instead of doing it yourself, unless you want to use it only on small pieces of furniture.