RESTORING A WOODEN TANNING DRUM
This year I restored a British made wooden tanning drum as an essential piece of equipment for the microtannery here in Devon.
With the decline of the leather industry in general in Britain, the move to stainless steel or polypropylene and generally the short supply of small scale tannery equipment, this small wooden drum is a rare find, likely one of very few similar machines left in Britain and perfectly suited to a microtannery scale.
From Pit to Drum
Skins and hides would historically be tanned in pits using varying strengths of bark tanning liquor. This is a very slow process, with bovine hides taking 6-12 months or longer to become fully tanned.
Above: The tanning pits at JF&J Bakers Tannery, Colyton, the last remaining Oak Bark Tannery in Britain
In the late 19th century, the tanning drum was introduced to speed up production, make tanneries more efficient and also suit new tanning technologies and materials such as new leather dyes and chrome tanning agents.
The key transformation of a tanning process when utilising a drum rather than a pit is the amount of movement or ‘agitation’ of the skins and hides, with more agitation meaning the process happens more quickly. Whilst traditional tanning pits would typically be fitted with ‘rockers’ that gently rock the skins from side to side, a drum provides much more mechanical action by comparison.
For Bay Tine Tannery, a drum means my 100% vegetable tanned deerskins will be processed more quickly, but also more evenly and predictably, creating a more consistent finished article.
A British Made Wooden Drum
The wooden drum was originally built by Beamhouse Engineering in Northamptonshire in 1991. It would have been built as a ‘laboratory’ size drum for larger tanneries to test different processes before scaling for their main production, however it is the perfect size for a micro tannery.
Whilst stainless steel and polypropylene started becoming adopted as materials for tanning drums in the late 20th Century, wooden drums still have their beneficial qualities for tanning drums. Wood is naturally insulating and so can provide some benefit to managing temperatures. It also has a naturally softer surface texture which is gentler on fine grain leathers.
After this drum was built, it was exhibited at the ‘Semaine du Cuir’ leather exhibition in Paris. It subsequently spent some years at the Institute for Creative Leather Technologies (ICLT) in Northampton. Prior to arriving at my tannery in Devon, the drum had sat unused for a number of years and was in need of a lot of attention with some repairs and maintenance
Above: The drum being exhibited at the 1991 Semaine de Cuir Leather Exhibition in Paris
Bringing the Drum Back to Life
Wooden drums rely on the moisture content of the timber ‘staves’ to stay watertight and so if wooden drums sit dry for a number of years they can shrink to the point where they will not re-seal. However, fortunately this drum had been kept in sufficiently humid conditions that this was not the case and it quickly retained the critical function of holding water.
The main areas that needed attention were the steel frame, the motor and the outer shell of the drum.
Above: The drum as received and before any restoration
Firstly, the base of the steel frame was almost completely corroded so this had to be cut away and a new steel base welded on. The old and new steels had to be painted to provide protection given the inevitable splashing of liquors and other baths from the tanning process.
The sub-frame of the door was leaking with the original rubber seals having degraded and so this needed to be taken off, the wood beneath cleaned up and new seals putting on so that the door would be watertight.
Given the length of time sat unused, the motor was completely seized and needed to be freed off. In particular, the brake plate on the motor which ensures it will stop quickly when needed had to be mechanically released.
The outside of the wooden drum shell was in a poor state, being completely covered in moss and dirt and with the protective timber stain having been worn away. So, the outside of the drum was all sanded back to provide a bare wooden surface that could then be finished with two new coats of a durable wood stain that could withstand the various solutions and liquors used in the tanning process.
Lastly, the steel guarding cage that goes around the drum for safe operation had to be put together. The sections that came with the drum did not provide a complete set and so some additional pieces had to be fabricated to finish the guarding.
Above: The drum after the restoration was complete
Living History: The people behind the industry
It was a humbling, challenging and fascinating process restoring this old piece of tanning equipment. It also brought me into contact with some amazing people who hold a wealth of knowledge and experience of tanning and leather making, including the company who built the drum who are still in operation, ex-tannery workers including the electrician who originally wired up the machine and controls and ex-tannery engineers.
These are people, for the most part, at the end of their careers in the leather industry or having already retired from their work in tanneries, making it all the more important to learn from them and try to keep as much knowledge intact as possible.
A New Life for an Old Drum
The drum is now the heart of the tannery and serves as a crucial piece of equipment in my process. It is such a great feeling to save such a machine from the scrap heap and give it a new lease of life in the remembering of an endangered, heritage craft here in Britain.
Watch the process of the drum restoration as it unfolded:
Head over to our web shop where the finished goods available are crafted from leather tanned in this wooden drum:
https://baytinetannery.co.uk/collections/all