Tanning (oak bark)
The process of using oak bark tanning to convert raw hide/skin into leather. For vegetable tanning and chrome tanning see the separate entry for tanning.
|Historic area of significance|
|Area currently practised||Devon|
|Origin in the UK|
|Minimum no. of craftspeople required|
|Current no. of trainees|
|Current no. of skilled craftspeople|
|Current total no. of craftspeople||1 business|
There are two types of leather – full grain and top grain. Full grain leather is leather that has not been tampered with after removing it from the animal – the hair is removed and the grain or epidermis is left on. Top grain leather is worked with to cover up any scars or blemishes on the skin and is usually sanded and sprayed.
The process of tanning varies according to the intended use of the leather; the end product. However, generally in the preparation for tanning, larger animal hides are divided and cut according to body areas, while smaller animals (e.g. calf, goat, pig and reptiles) are left as one piece. Firstly the hair must be removed from the skin. The hides and skins are in water to be washed and rehydrated, with lime liquors used to loosen the hair and plump the hide. The hair that has been removed is sold on to plasterers or felt manufactures. The hides and skins are naturally uneven and of different thicknesses. Therefore, in order to even them out they are run through a plotting machine. Thickness throughout a hide differs, hence why leathers are shown to have different thicknesses on their labelling.
Oak tanning at J & F K Baker. & Co Ltd. Photo: Jonathan Slack
The tanning process consists of putting hides in weak solutions of tannic acids which gradually increase in strength. The tanning operation varies in time from 3 weeks to 3 months, dependent on the type of hide being tanned and the thickness of it. The leather is then dried in such a way that the leather does not diffuse into ‘grain’ or the ‘flesh’ using oils applied to wet leather which form a film to arrest this diffusion. While still wet, the leather is ‘set out’ removing creases and ‘rolled on’ to help make the characteristic smooth surface of leather. The leather is thoroughly dried out and ‘rolled off’ on very heavy pressure rollers which gives the polish to the finished leather.
England traditionally used oak bark to tan skins and hides. The traditional oak bark process differs slightly from that mentioned above. Oak bark is stripped from trees during the spring and summer seasons. It is dried out for two or three years and then ground down. The tan is soaked out of the bark using cold water. When the tan is strong enough, it is pumped up to the tan yard. There are different pits which the hides pass through. They are suspended by sticks for the first three months. The sticks are then removed and the hides are laid flat, one on top of the other into deeper pits where they remain for nine months. The raw hide becomes leather. When the hides are taken out of the pits, they are dried for two or three days, at which point they are ready for finishing. A downside of using oak bark today is that it is a slow process, requiring twelve months for tanning. However, it is hardwearing and produces a strong textile. Oak bark tanned leather lies at the high end of the market.
Different people do different parts of the job. There are crossovers where they do other people’s jobs, but no one person does it all. Tanners would be working in the tanyard, limeyard men working in the limeyard, curriers would be staining and dressing leather and then those in the machine shop who would be splitting and shaving. Some people might do more than one of those.
Issues affecting the viability of the craft
Only one surviving oak bark tannery (J. & F.J. Baker & Co. Ltd.), where most of the processes are carried out by hand. Some hand processes alongside mostly machine processes in other tanneries.
Lack of awareness: Although the leather has better tensile strength, looks nicer, and lasts longer than machine tanned leather, these qualities might only show after twenty years’ wear. Customers need to be made aware of this and understand what goes into the whole process.
Training issues: Training is done within the business, with the most experienced people training the newcomers in the various processes. Enough people (not more than two at any one time) are being trained to meet the current market. They should still be able to earn a living in twenty years time.
Market issues: There are a lot of available markets, but someone has to go and look for them to enable the business to thrive. These include shoes, saddlery, luggage, and fashion goods. Again, company buyers need to be educated regarding quality if our production is not to lose out to cheaper machine processed leathers.
Supply of raw materials: Supply of hides is local and safe. Local hides are used and generally the standard is quite good, although a premium is paid for selection. Materials are bought through a hide merchant, and they buy from the abattoir, and they know what is needed.
Craftspeople currently known
- J. & F.J. Baker & Co. Ltd. – based in Colyton, Devon. Britain’s last remaining traditional oak bark tannery.