Tanning is the process by which raw animal hides are made softer and more durable for use in clothing, shoes and other products. There are various traditional methods used to tan leather, including oak tanning. Oak tanning uses the natural tannins found in oak, and especially oak bark, to induce the necessary reactions. Oak tannins also have medicinal properties as an astringent and mild antiseptic, which make it useful in the treatment of inflammation and minor wounds.
Things You'll Need
Oak bark or wood
Large stainless steel pot
Shred oak bark (and wood, if any) in a wood chipper to create pieces 1 to 2 inches across. If you do not have a wood chipper, you can buy shredded oak bark at a garden supply store.
Fill a pot halfway with water and bring it to a simmer.
Put the oak chips into the water and soak them until the solution of tannin is at the desired strength, about one to eight hours. You can judge the strength of the solution by color and flavor. A darker solution is stronger (bearing in mind that heat also darkens the color of tannins), and a strong solution of tannin will have the dry, astringent mouth feel of strong tea or red wine.
Pour off the solution and save it. Repeat the steps with the same oak chips to create a weaker solution. If desired, pour off the second batch and repeat to create a third, even weaker solution.
Use soft water for the best results when tanning hides, as the minerals in hard water can react with the tannic acid to blemish or discolor leather.
Heating tannin darkens it and will create a darker tanned leather. For lighter tannin solutions, soak bark for 1 day or more in water at a lower temperature.
When tanning leather, dilute the weakest solution, then move the leather to progressively stronger tannin solutions throughout the tanning process.
Iron or aluminum pots and implements will react with the tannic acid to discolor leather.