“Traditional leather making” usually means the methods used before chrome tanning, which was developed in the 1850s and became the industry standard. Most traditional methods use plant tannins, but the category also includes brain tanning with smoke, alum tawing and oil tanning. These methods can produce excellent leather. They are slower, rely on local materials, and carry their own hazards.
Traditional methods at a glance
| Method | What does the tanning | Typical time | Typical result |
|---|---|---|---|
| Bark (vegetable) tanning | Plant tannins from bark, wood and leaves | Weeks to months in pits; about a year for traditional oak bark | Firm, sturdy leather that darkens and develops a patina |
| Brain tanning | Fats from brains, followed by smoking | About 1 to 3 days of hands-on work after soaking; a week or more in total | Soft leather that stays soft after getting wet, once smoked |
| Alum tawing | Alum and salt | A few days to about two weeks for home kits | White leather that is not permanent in water |
| Oil (chamois) tanning | Oxidised fish oil | Varies widely | Soft, pliable leather |
Bark (vegetable) tanning
Vegetable tanning is the oldest method still used for quality leather. It uses tannins from oak, chestnut, hemlock, mimosa (wattle), quebracho and sumac. Tannins bind to collagen, making it less soluble in water and more resistant to decay.
Traditional bark tanning happens in pits. Hides move through a series of pits, starting in weak tan liquor and ending in stronger liquor. Building the strength up gradually keeps the outer surface from tanning and hardening before the inside has been penetrated.
Timing varies a lot. Pit tanning usually takes four to 12 weeks, and traditional oak bark tanning can take about a year or longer. J & F J Baker, in Colyton, Devon, is one of the best-known surviving oak bark tanneries in the UK.
Bark tanning is not the same as soaking leather in tea. It takes months, using liquors of different strengths.
Old ways of preparing hides
Before modern chemicals, hides were prepared with methods that now sound unpleasant, many of them used in medieval tanneries:
- Dehairing used wood ash, a lime slurry, or “sweating,” where the hides were left to begin rotting so the hair would loosen. In some places, stale urine was used.
- Bating, which softens and cleans the hide, used dog or pigeon dung. Its enzymes helped soften the skin.
Modern tanneries don’t use urine or dung, although a few traditional sites still do. The Chouara tannery in Fez, Morocco, uses quicklime and pigeon dung in open stone vats, along with plant dyes.
“Traditional” does not mean safe. Lime is caustic, and dung and urine can carry pathogens.
Brain tanning
Brain tanning is one of the oldest ways to make soft leather. Brains contain fats, such as lecithin, that act as emulsifiers. They coat the hide’s fibres and keep them soft. Strictly speaking, brain tanning is an oil or emulsion tannage rather than a tannin tannage. The old saying that every animal has enough brains to tan its own hide is roughly true for deer.
A basic brain-tanning method runs like this:
- Remove the hair and prepare the hide.
- Remove the membrane from the flesh side.
- Soak the hide in a brain solution.
- Wring it out.
- Stretch and work the hide constantly while it dries.
Brain-tanned hide needs one more step to stay soft after it gets wet. That step is smoking. Brain-tanned deer is the classic “buckskin.” Deer leather is usually called deerskin, as explained in hide vs skin.
Smoking
Without smoking, brain-tanned hide goes stiff again when it gets wet. Smoking sets the leather so it dries soft after wetting. It also colours the hide from pale tan to brown, depending on the wood and how long the hide is smoked. Aldehydes in the smoke act as a light tannage.
Traditional smoking used punky or rotten wood and cool smoke. Smoke hides outdoors only, because carbon monoxide builds up in enclosed spaces.
Alum tawing
Alum tawing uses aluminium salts (alum) and salt, often with egg yolk and flour in older recipes. It produces white leather, and it was already in use in ancient Egypt. It isn’t a true tannage, though. Water washes the alum out, so alum-tawed leather isn’t permanent the way bark-tanned leather is.
Oil (chamois) tanning
Oil tanning uses fish oil, traditionally cod oil. The oil oxidises inside the skin, which tans it. The result is soft, pliable leather, such as chamois.
Where traditional tanning survives
Traditional methods now survive mostly in small workshops and a few specialist tanneries. J & F J Baker in Devon and the Chouara tannery in Fez are two examples. For how modern tanneries are organised, see what a tannery is.
Is traditional leather better?
It depends on the use. Bark-tanned leather is firm and holds its shape, which suits soles, belts and saddlery. Brain-tanned leather is soft and drapes well, which suits soft garments. Chrome tanning is much faster. Its health and environmental questions are covered in is chrome-tanned leather toxic?
For how long each method takes, see how long it takes to tan leather. For how these older methods fit alongside the modern stages, see how leather is made.
Misconceptions
- Brain tanning uses tannin. It doesn’t. Smoking is a separate finishing step.
- Alum-tawed leather lasts like bark-tanned leather. It doesn’t, because water removes the alum.
- Traditional means non-toxic. It doesn’t. See the safety notes below.
- Bark tanning is soaking in tea. It takes months, with liquors of different strengths.
Safety
Lime and wood-ash lye burn skin and eyes, so wear gloves and goggles. Smoke hides outdoors only. Deer brains can carry chronic wasting disease (CWD), so avoid brains from animals in CWD areas, and wear gloves when handling them.