Vegetable Tanned Leather – Process and Benefits

Vegetable tanned leather

Vegetable tanning refers to leather that is tanned with fruit, roots, leaves, oak and spruce bark. Materials like quebracho, tara pods, olive leaves, rhubarb roots and mimosa are also common. These substances are placed in a pit along with the skins and hides. Since these tannins are derived from plants, the leather is called vegetable-tanned leather. Vegetable tanning takes far more time than chrome tanning, which can be done in a day, but it is far more worth it environmentally.

History of Vegetable Tanned Leather

Vegetable tanning is the oldest method of tanning. It has existed for over 5,000 years. Some evidence revealed that vegetable tanning was around in the 4th millennium BC in Egypt. Several types of leather were prepared for various uses in the ice of the Alps. Recently, we found that more modern industrialized tanning methods have become common, and it can be assumed that nowadays only 10 – 12% of all leather is vegetable-tanned. Historically, each region or country has its own materials that they use for the tanning process. In Europe, they mostly use chestnut and in the UK they use oak.

Is leather sustainable?

Large scale production of leather using hash chemicals can cause serious impacts on the environment, but there are more sustainable options. Tanning with vegetable materials and using the by-product of meat and dairy farming significantly reduces the environmental impact.

Tanning with chromium has a negative impact on the environment, especially with a lack of waste treatment. Besides the use of chromium, the amount of water required for the tanning process has become a second concern. Also, as it is a by-product of the meat and dairy industry, it could be argued that should be included in the environmental impact as well. By using hides as leather raw material, it should reduce the waste of these industries significantly.

Nowadays, so many products are created using vegan leather, but these still cause environmental impact as they use synthetic materials, like PVC, that derive from fossil fuel like petroleum. Also, water waste and sometimes toxic dyes are additional environmental impacts of the faux leather industry. Some vegan leathers are made using cork or pineapple leaves, but these still require plastic-based adhesives to hold the fibers together.

Tannins

Every plant contains a different percentage of tannin. A stressful reaction such as a parasite attack causes the plant to release this substance. Even within the same plant type, the tannin content varies:

Oak bark contains about 10% tannins (in older trees about 5%) and oak apples up to 70%. The resulting leather will be light brown.
Chestnuts can reach 10%tannins in the wood of old trees. The leather is medium brown and chewy.
Willow bark has 10% tannins and delivers yellowish leather.
Spruce bark has 15% tannins. However, in spruce wood it is a maximum of 1%. This leather is light brown.
Valonea has a very high tannin level with 32%. The leather is tough and solid.
The bark of old birch contains 10% tannins. The resulting leather is also yellowish and soft, but resistant.
Galls or cecidia contains 55–65% tannic acid. There are over-growths on these plants with the eggs of insects. Around those larvae, tannin-containing growths develop. The countries of origin for this plant are Hungary, Yugoslavia and Austria.

Vegetable Tanning Process

Pre-Tanning

The pre-tanning process involves preparing the leather by rehydrating the hides and removing the hair over a couple of days.

Tanning

Here’s a great video from pellevegetale that provides an overview of this process:

The tanning agent is placed together with the hides in water-filled pits, resulting in a bath containing tannic acid after a few days. The skin is regularly exposed to additional baths with higher tannin concentrations and must be frequently tended to in order to ensure full absorption. The hides are then removed, excess moisture is taken out and they are shaved to the desired thickness (from the backside).

For vegetable tanned leather that isn’t dyed, this is nearing the end of the process. That type of vegetable tanned leather has a pale pinkish color to it. While dyed vegetable tanned leather needs a further dyed process to get a rich color and character.

Dyeing, Hot Stuffing, Drying

For tanned hides ready to be infused with color, the next step is for the hides to be dyed in enormous drums and rotated. The leather may then be hot stuffed, which is a special process that literally stuffs the leather hide to its core with waxes and tallows that give it a rich color and make it more durable. Then, the hides are dried and staked. Staking is a process that softens up the leather just a bit.

Finishing the Leather

Finally, the hides are sprayed with waxes and a sealant for protection. The entire process is very time and labor intensive, taking up to six weeks to complete the entire process, which is why the price of vegetable tanned leather is higher than chrome tanned leather.

Lightening and Darkening Vegetable Tanned Leather

Uncoloured vegetable tanned leather will darken with exposure to light, moisture and fat, but the dyes in pigments or aniline leather will become lighter with exposure to light.

Vegetable tanning will become darker the first time that it is oiled,moistened or greased, and brighten as it dries. Apparently this effect is related to oils and fats in the leather. At first, grease moves up to the top of the leather and darkens, but the dryness makes it brighter with time because of the fats slowly drying out. But as soon as water or grease gets onto the leather, it darkens strongly.

The light fastness of vegetable-tanned leather - walklo leather — Walklo Leather The light fastness of vegetable-tanned leather

The Benefits of Vegetable Tanned Leather

All in all, the main benefits of vegetable tanned leather are:

A longer life: Leather briefcases and handbags are often so long-lasting and so loved that they pass from generation to generation.
More eco-friendly: Vegetable tanned leather is more eco-friendly than its siblings – Synthetic Faux Leather and Chrome Tanned Leather.
Safety: The process is traditional and safer for those tanning the leathers.
A rich patina: Any vegetable tanned article that is used everyday ages in a way that enhances its character and its beauty.

Find our best vegetable tanned leather product: backpack, wallet, messenger bag.