How to Age Vegetable Tanned Leather
What is vegetable tanning?
Vegetable tanning is a method of using plant material like bark and leaves to convert animal skins into durable leather. This multi-step process is time consuming, often taking over 6 months to complete, but it creates a beautiful, long-lasting leather that continues to interact with its environment, building up a rich umber patina over time with exposure to natural elements.
Sun, oil, and water
Sunshine darkens vegetable tanned leather much like it tans human skin. As the sun’s power varies depending on season and latitude, so does its effect on leather. While I was on vacation in North Africa over the summer, the Valerie leather strap bracelet in the above picture darkened considerably with exposure to the sun’s strong rays. Dips in the ocean would soak the leather, then it would dry out quickly as I wore it on the beach. This wet-dry cycle aged the leather quickly, but oils from my skin added a conditioning element, so the leather never stiffened or dried out. Instead, it became quite soft, conforming to the shape of my wrist.
Speeding up the process
Some leather accessories don’t get a lot of exposure to sun, water, and oil. The Devilish Wallet in the above picture (right) shows about 5 months of wear. In comparison to the brand new wallet on the left, it has developed a light golden color from the natural oils in my hands and the absorption of sunlight as it sits on my desk. If I wanted to speed up the patina process, I could emulate the history of the Valerie Bracelet – increasing the amount of sunlight, water, and oil that the leather receives. Strong, direct sunlight will darken leather faster than weaker, indirect sunlight.
Water won’t necessarily harm leather, though vegetable tanned leather is very malleable while wet and will retain any new shape you give it while it dries. (This is how gun holsters are made.) Water will also darken vegetable tanned leather slightly when it dries.
Applying any natural oil will both darken and moisturize vegetable tanned leather. Typically, leatherworkers only work with animal oils like neatsfoot oil or mink oil. Neatsfoot oil comes from the shinbone of the cow (etymologically, “neat” was once used as a word for “cow”, and “foot” loosely refers to the lower leg of the animal.) Mink oil is derived from the fat tissue of the mink. There are varying reports of success with vegetable oils, though some report rotting after longterm use on horse tack.
Is it Real Leather?
Not all leather will interact with sun, water and oil like vegetable tanned leather. 90% of worldwide leather production uses chrome tanning as a quick method to convert animal skins into usable material. Chrome tanned leather is essentially chemically sealed from further interacting with the elements, making it nearly impervious to stains. This also leaves the leather without the additional textile dimension of vegetable tanned leather, sometimes demanding the question “Is it real leather?”
- Barrett Alley