Bark-Tanned Leather: Oak Bark, Pit Tanning and How It Differs From Ordinary Vegetable Tan

Bark-tanned leather is vegetable-tanned leather made with tannins from tree bark, traditionally oak. The tannins are steeped into a liquor, and hides are left in it for months. At the one UK oak-bark tannery described below, the whole process takes about 12 months.

Ordinary vegetable tan is the wider family. It can use tannins from bark, leaves and other plant parts, and a modern US tannery that uses mimosa and quebracho tannins describes a process of about six weeks. Bark tanning is the slow, traditional end of that family, and the sources we read link it to belts, bridle and shoe leather, not to jackets.

This page is part of our guide to leather tanning and production.

Bark tanned vs vegetable tanned

Every bark-tanned leather is vegetable-tanned, but not every vegetable-tanned leather is bark-tanned.

The word "tan" itself comes from medieval Latin tannum, meaning oak bark.

For the general definition, see what is vegetable-tanned leather and vegetable-tanned leather: how it is made and used.

How pit tanning works

The best-documented modern example is J & FJ Baker in Colyton, Devon. A Farmers Weekly feature calls it Britain's only oak-bark tannery.

• Bark. It comes mainly from Wales and the Lake District, a mix of mature and coppice oak, with coppice preferred because it has more tannin. The bark is stored for at least three years.
• Liquor. Water and bark make the liquor; it takes about a month in summer and 6-8 weeks in colder months.
• Preparation. Hides are rehydrated for 24 hours, limed in a 2% lime solution for about a fortnight, dehaired and defleshed.
• Pits. There are 72 pits holding 12 or 24 hides each. Hides start in weak liquor, which is strengthened over time to avoid uneven tanning.
• Layering. About three months hanging in liquor, then about nine months in a pit layered with raw bark.
• Finishing. Equestrian leather is dressed with oils, often fish oil, and greases.

How long it takes

Sources give very different times. They describe different methods and eras, so they cannot be combined into one number.

A craftsman at a leather merchant talks about oak-bark bridle leather from the Devon tannery. He gives about 14 months for the process, where the Farmers Weekly feature above says about 12.

Which barks

Oak and hemlock are the two best documented. Hemlock bark had a tannin content of 10 to 12 percent and gave a deep reddish-brown leather, while oak gave a lighter, yellowish one.

Wikipedia lists the barks used in modern bark mills: chestnut, oak, redoul, tanoak, hemlock, quebracho, mangrove, wattle and myrobalans. Wattle comes from the bark of Acacia mearnsii.

A short history: hemlock and oak

In the 1800s bark tanning was a large industry, as Northern Woodlands describes. Up to 64 tanneries worked in New York's Catskills, and an estimated 70 million hemlock trees were harvested for their bark.

By the early 20th century imported tropical barks, chromium, oils, aldehydes and synthetics were replacing plant tannins, and hemlock bark tanning had largely ended.

Why it looks and ages differently

A UK maker who buys from the Devon tannery says every stage is done by hand in small runs and that scars, blemishes, irregular dyeing and surface tallow are natural. It says the leather develops a distinctive patina. The same maker says only vegetable (bark) tanned leather develops a genuine patina.

That is a maker's view, not a test, and makers who sell the leather have a commercial interest. A Tuscan consortium makes a similar claim for its vegetable-tanned leather.

We found no sourced description of the smell, so we do not describe it here.

Where it is used, and where it is not

The sources read name belts, bridle and harness leather, shoe leather, purses and flask holders. Vegetable-tanned hide is described as not very flexible.

None of the sources we read names jackets or other garments for bark-tanned leather, and we found no tannery making jacket-weight bark-tanned leather. Leather Collection's jacket pages also do not state the tanning method. For the usual garment tannage, see chrome-tanned leather.

Buying notes

"Bark tanned" is a maker's description, and we read no standard that defines it. If it matters, ask the seller which bark, which tannery and how long the hides were in the pit.

For what the hide you buy looks like, see vegetable-tanned leather texture and appearance and vegetable-tanned hides: what to know. If you want a finished garment rather than a hide, see Leather Collection, which does not state the tannage on its jacket pages.

FAQ

What type of leather is bridle leather? In the sources we read, bridle leather appears as a heavy oak-bark-tanned leather from the Devon tannery, finished with fats and oils.

Is vegetable-tanned leather real leather? Yes. Vegetable tanning is one of the ways hides are tanned, using plant tannins.

Why did tanneries smell? Tannery odors came mainly from putrefying hides and trimmings, from hydrogen sulphide and ammonia, and from wastewater. See what is a tannery.