Oil-Tanned Leather: What Oil Tannage Is, Why It Pulls Up and How It Differs From Pull-Up Finishes

"Oil-tanned leather" means two different things. In the strict sense it is leather tanned with oils that oxidize inside the skin, as in chamois. In everyday leather selling it is usually chrome-tanned leather packed with oil and wax after tanning, a use one boot maker calls a misnomer.

The oil is why such leather can show a lighter color where it is bent or stretched, an effect called pull-up. This page separates the two meanings.

It is part of our guide to leather tanning and production.

Two meanings of "oil tanned"

The sources do not agree on one definition, so we show both.

True oil tanning: how chamois is made

Fish oil contains a lot of unsaturated fatty acids. They combine with oxygen, and that oxidation does the tanning. Fats from land animals lack this effect, which is why tanning with them is called "false tanning".

In practice the skins are drummed in oil, dried so the oil bonds with the fibers, and the two steps repeat. Excess fat is then washed out with soda water.

As Wikipedia's chamois article reports, the British Standard BS 6715 defines chamois as leather from the flesh split of sheepskin or lambskin, tanned by processes that involve oxidation of marine oils in the skin. In the US the unqualified word "chamois" is limited to the flesh split of sheep or lambskin tanned solely with oils.

Genuine oil-tanned chamois is very absorbent and has almost no abrasive quality. A retailer's glossary adds that it is washable and temperature-resistant up to 70 °C (158 °F), and that a "new chamois" is pre-tanned with formaldehyde and post-tanned with tannin.

The trade term: oil-tan leather

The trade term "oil tan" describes something else. One seller says it starts out chrome tanned, then the hide is packed with oil and wax, giving a semi-soft, semi-flexible temper. A boot maker says oiling is a post-tanning step and the leather is "impregnated" rather than tanned by oil.

Reported effects:

• Partly waterproof and softer, with less break-in.
• It takes up a lot of waterproofing product.
• The dye shifts under pressure and the leather lightens where oil moves away, which shows as pull-up.
• It can darken unevenly when treated.

These are sellers' descriptions, not lab results, and both have something to sell.

Is oil tan a tannage or a finish?

That is the disagreement. In the strict sense oil is the tanning agent. In the trade sense the oil goes in after the chrome or vegetable tannage, so it works more like fatliquoring and finishing.

One famous example sits in the middle. A UK reseller describes Horween's Chromexcel as a combination tannage with a bark retannage and hot stuffing, meaning oil and wax worked in under heat. That is a reseller's description, not Horween's own technical page.

Our pages on leather finishes and treated leather cover the finishing side. This page stays on tannage.

How to tell which one you have

We have no reliable home test, and we do not recommend burn or solvent tests. The practical way is to ask the seller what the tannage is and what was added afterward.

A drag test is an experiment on the surface, and we do not claim it identifies the tannage.

Where you meet it

The sources link oil-tan leather to work boots, belts and similar goods. Leather Collection's jacket and glove pages do not state the tanning method, so we cannot say whether any piece is oil-tanned in either sense. Ask the maker before you buy. For the main leather types, see Leather Collection's guide to leather types.

For the chrome base, see chrome-tanned leather. For what the word "tanned" tells you, see what does it mean to tan leather. For the feel of leather, see what makes leather soft.

FAQ

What is oil-tanned leather? Either leather tanned with oxidizing oils such as cod oil, as in chamois, or leather sold under that name that was tanned another way and then packed with oil and wax.

Is oil-tanned leather real leather? Yes in both senses. Both are tanned hide.

Is chamois oil tanned? Yes. Chamois is the classic oil-tanned leather, tanned with marine oils.