Fumed, or smoked oak is oak wood flooring which has been treated to change its colour. Fuming or smoking involves putting the oak into an enclosed environment in which ammonia is introduced into the atmosphere. This enclosed environment might be a closed tank or a sealed tent or some form of container into which only a relatively small amount of ammonia is introduced. The effect of the ammonia in the air is that the colour of the wood is changed.
It is a common mistake that fuming or smoking oak involves the application of the ammonia to the oak, but this is not the case. The change in colour comes about from the wood’s reaction to the presence of ammonia in the atmosphere. Effectively what happens is that the ammonia causes the tannins in the wood to be brought to the surface. The closer the tannins are to the surface, the darker the wood will appear. The longer the wood is exposed to the ammonia, the darker it becomes. The results obtained from fuming or smoking will range from a rich brown colour to almost black.
Essentially, the intensity of the colour and the tone of the colour will depend upon the length of time the wood stays in contact with the ammonia fumes. Periods of as little as twelve hours will provide a lightly fumed effect and 72 hours a darker end result. Furthermore, the higher the temperature in the chamber, as you would imagine, the quicker colour change results will appear, but not only that, the tone will be affected. Hotter temperatures typically introduce red tones and cooler temperatures green tones allowing for creativity when it comes to the fuming or smoking process.
The fuming of Oak is carried out to bring out the natural tannins in the Oak, ammonia brings the tannins to the surface and the colour variation you will get naturally is because each piece of wood is unique and some will have tannins near the surface and some deeper down. The nearer the tannins are to the surface the darker the finished board. You can get a rich brown to a virtual black colour. The longer the boards are left in the chamber the darker they become.
Smoked Oak is treated in the same way but with a different mix of ammonia and in some cases to get the warm golden colour without the extremity of colour variation we introduce wood smoke into the chamber
Fuming Oak is not staining or applying ammonia direct to the wood, the ammonia would not penetrate the total thickness of the wood. Fuming Oak means that the oak wood is subjected to ammonia in the atmosphere. If you look in old horse stables you will see that where the horses urinate the ammonia in this has risen to the oak beams or other timber above when it gets warm and is considerably darker than timber that has not been subject to the fumes. This is why it is called fuming.
Processing the timber in the chamber for 48 hours for light fuming and up to seven days for our fully fumed boards. The chambers used are also heated and for really dark boards its usually increase the heat considerably which also has the effect of hardening the oak. Hot temperatures will create reddish tones and cooler temperatures green hues to the tone.