Chrome tanning takes about a day in the drum. Raw hide to finished leather usually takes one to three weeks, including drying and finishing. Vegetable tanning takes much longer, with days or weeks in drums and months in pits. Traditional oak bark tanning can take about a year. Times vary with the hide, the method and the tannery.
Quick comparison
| Method | Tanning step | Whole process (roughly) |
|---|---|---|
| Industrial chrome | About 6 to 24 hours in a drum | About 1 to 3 weeks, raw hide to finished |
| Vegetable, drum | About 1 to 3 days | Plus several days of drying |
| Vegetable, pit | About 4 to 12 weeks | Longer; traditional oak bark about 12 months |
| Home brain tanning (deerskin) | About 1 to 3 days of hands-on work after soaking and fleshing | About a week or more |
Before tanning: curing and beamhouse
These steps take time too. Hides are often salted and drained for several days to a few weeks before processing. The beamhouse, covering soaking, liming, deliming, bating and pickling, usually takes about two to four days. Each step is described in how leather is made.
Chrome tanning: about a day
Chrome tanning is fast because chromium salts penetrate the hide quickly. In a drum, the tanning step usually takes about six to 24 hours. The hides come out as “wet blue,” named for their colour. That blue can still show in the cut edge of finished leather, as how to identify chrome tanned leather explains. Chrome’s speed comes from its chemistry, not from cutting corners. Its health and environmental questions are covered in is chrome-tanned leather toxic?.
Vegetable tanning: weeks to a year
Plant tannins move through a hide more slowly than chromium does. In a drum, the tanning step takes about one to three days. In pits, where hides move through stronger and stronger tan liquors, it usually takes four to 12 weeks. Traditional oak bark tanning can take about a year, and medieval sole leather could spend 12 to 18 months in the pits.
Thick hides take longer than thin ones. Cowhide for sole leather is a good example. Pit tanning suits firm leathers such as soles, belts and saddlery. More on bark and pit methods is in traditional leather making.
After tanning: drying and softening
Tanning isn’t the end of the process. Drying can take as long as tanning itself. Leather still needs retanning, dyeing, fatliquoring and finishing, and drying and softening (staking or milling) can take as long as the tanning.
How long home tanning takes
Home methods vary with the animal and the method:
- Brain-tanned deerskin: about 1 to 3 days of hands-on work after soaking and fleshing, and about a week or more in total.
- Smoking a brain-tanned hide: about 30 minutes to a few hours per side.
- Alum or commercial kit tanning of hair-on pelts: a few days to about two weeks. Follow the kit’s directions.
- Small pelts, such as rabbit or squirrel, are faster because they are thinner.
Use gloves and eye protection with lime and other caustic chemicals.
What changes the time
- Hide thickness
- Tanning method
- Temperature
- Concentration of the tan liquor (the tanning bath)
- Agitation, such as drums compared with pits
- pH
Common misconceptions
- Drying a hide is tanning. It isn’t. Untanned, dried hide is rawhide.
- Faster tanning means lower quality. Not necessarily. Chrome is fast because of its chemistry.
- The hide is done when the tanning bath ends. It still needs oiling, drying and softening.
- Longer pit tanning is better for every use. It suits firm leathers such as soles, belts and saddlery.
Do not start with a spoiled hide
Hair that slips easily and a bad smell mean bacteria are already breaking the hide down. Spoiled hides are hard to save, so start with fresh or properly preserved material.