Case Study - 48 Hour Fumed Oak


Fuming is a wood finishing process that darkens wood and brings out the grain pattern. It consists of exposing the wood to fumes from ammonia which reacts with the tannins in the wood. The process works best on white oak because of the high tannin content of this wood. Each board having a different grain structure will take in different amounts of ammonia and the finished colour will not be uniform. Also you can get lighter streaks in the boards and this is to be expected. Every batch of flooring will vary slightly. If you want a uniformed finish with minimal colour variation then this process is not for you.

Fuming has an advantage over staining/colour oiling in that it does not obscure the grain, it just darkens it. Fuming has the disadvantage that it is not a very precise process. Different batches of wood will react to fuming differently. Once a floor has been fumed it will still continue to change colour and they do tend to even out, as does a normal oiled flooring, after being laid.

The longer the floor is exposed to ammonia the darker it will become which is why we single, double and triple fume.

Fuming was an accidental discovery in England after it was noticed that oak boards stored in a stable had darkened. This was caused by the ammonia fumes from the horse urine reacting with the wood. At the end of the nineteenth and beginning of the twentieth centuries fuming became popular with furniture makers in the Arts and Crafts movement.


Our Showroom Floor – Fumed and Tumbled.

Above is our existing showroom floor taken three years ago. Please excuse the soiled dusty look. This is the only archive photo we could find. The two planks placed on the floor were kept in the absence of light since the floor was originally laid in 2013. You will see just to the right of those planks some boards on the floor with light lines running through them. Those lighter lines were the same as the very light grain in the stored planks. The light line in the laid floor has toned down over time due to Ultra Violet sunlight.

Our clean Showroom Floor – June 2023

Above is a new floor made four weeks ago (May 2023) with one such board to illustrate how sapwood will appear. This is a special order floor made in face widths of 220 mm and 260 mm. We can not guarantee how much sap will be in the floor but normally it is a small amount. It is not until the oak is fumed that it shows out. It is possible to colour out some of the sap if required to do so once the floor is laid but that is only to be done by a person with the correct materials and experience.

The fuming process used results in a chemically reactive colour change in the oak.
Oak naturally contains Tannic acid. The lighter shade (Almost white) is sapwood which contains very little acid if any. When Oak is exposed to Ammonia fumes, the ammonia reacts with the tannic acid resulting in the colours seen. The more concentrated the acid is in various sections of the plank the darker the reactive colour. When we use colour Staines on oak the pigments make over the natural characteristics and colour variation. The beauty of fuming is that the oak gets to keep its natural identity and grain variations.

The following are more images showing the beauty of the  fumed Oak

The following are 24 hour fumed.


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