Leather 101

Leather 101

Where does leather come from?
Leather is made from animal skins, primarily cattle, and is a byproduct of the meat industry. The hide which remains after the meat is removed is sent to a tannery to be turned into leather.

What is ‘tanning’?
Tanning is the process of cleaning and preserving a hide so that it is stable and doesn’t decay which is what transforms it into leather. The word “tanning” comes from the traditional use of tannins to stabilize the hide. Technically, an animal skin is not leather until it is tanned.

Methods of leather tanning:

Vegetable Tanning
: a traditional process that uses ingredients made from tree bark to preserve the hide. The result is leather that tends to be more firm and has simple natural color shades. Veg tanned leather can be wet formed and is useful for making things like gun holsters, saddles and other heavy duty items. It is not stable in water and will shrink, harden and eventually break down if not sealed.
Chromium Tanning: a method of preserving leather using Chromium salts which results in more supple and flexible skin that is more easily transformed into a wide range of colors, textures and tempers. It is also more water stable than veg tanned leather. The vast majority of Mitchell products are made with Chrome-tanned hides.

Types of leather and quality:

Full Grain
– the most expensive and highest grade of leather where the hides are used with the skin surface as is, showing the grain and marks accumulated by the animal. Only the cleanest and nicest hides are used full grain and result in the most natural looking leathers. Also, because the skin of the animal is where tensile strength is strongest, the unaltered full grain hides tend to be the most durable and long lasting leathers.
Top Grain – the next best grade of leather after full grain, these are hides that have their skin surface sanded or buffed to eliminate marks and imperfections. They are then stained, dyed or pigmented and sometimes textured (corrected grain) to give the leather more character. The tensile strength of these leathers is very good but not quite at the level of the unaltered skin of a full grain leather.
Splits – a lower grade and less expensive leather where hides are split into two or more thicknesses and the flesh (suede) side, rather than the skin portion, is buffed and made into a new piece of finished leather with the techniques mentioned above. These hides have the lowest tensile strength and long term durability because they do not contain the actual skin surface of the animal.

Coloring of leather:

Aniline Dyed –
The most natural method of adding color to leather where a transparent soluble dye allows one to see the grain and character of the skin through the color and finish.
Semi-aniline – Very similar to above but with an additional coating that may contain some pigments to provide more protection and make the color more uniform.
Pigmented – non soluble and non transparent pigments (more like paint) are used which result in a more synthetic overall appearance than either of the above. Pigmented leather has the further disadvantage of looking like peeled paint as it wears rather than aging gracefully like the aniline leathers

Pull up leather:
A quality of certain aniline leathers which are deeply impregnated with oils and waxes.  When the leather is bent or pulled, the oils move around within the skin causing lighter tones and interesting colors to become visible.  Most people find this effect quite pleasing as it gives the leather more interesting character that changes with use.  Pull up leathers are also a sign of good durable tannage and finishing where the leather is well moisturized and protected by all of the oils impregnated into the hide.  Pull up leathers have the advantage of aging well and looking more interesting as they distress.  At Mitchell we love pull up leathers.  Horween's Chromexel is perhaps the ultimate example.