Leather FAQ's

Vegetable-tanned leather is tanned using tannin (hence the name "tanning") and other ingredients found in vegetable matter, tree bark, and other such sources. It is supple and brown in color, with the exact shade depending on the mix of chemicals and the color of the skin. Vegetable-tanned leather is not stable in water; it tends to discolor, and if left to soak and then dry it will shrink and become less supple and harder. In hot water, it will shrink drastically and partly gelatinous, becoming rigid and eventually brittle. Boiled leather is an example of this where the leather has been hardened by being immersed in hot water, or in boiled wax or similar substances. Historically, it was used as armor due to its hardness and light weight, but it has also been used for book binding. This is the only form of leather suitable for use in leather carving or stamping.

Leather thickness is usually measured in ounces. One ounce equals 1/64" in thickness. Thus, a weight of 4 to 5 oz. means the leather is 1/16" to 5/64" in thickness. The thickness of leather varies to some extent throughout the hide. This is why leather is usually shown with a range of thickness such as 4 to 5 oz., or 6 to 7 oz. As a comparison, a quarter (coin) is equal to a 4 oz. thickness. A standard thickness for belts is 7 to 8 oz leather.

Ounce	MM	% Inch	Decimal Inch
1	0.4	1/64	0.016
2	0.8	1/32	0.031
3	1.2	3/64	0.047
4	1.6	1/16	0.063
5	2	5/64	0.078
6	2.4	3/32	0.094
7	2.8	7/64	0.109
8	3.2	1/8	0.125
9	3.6	9/64	0.141
10	4	5/32	0.156

Like raw denim, vegetable tanned leather wears gracefully and molds to the owner's habits over time. All vegetable tanned leather darkens and develops a natural patina over time with exposure to natural elements like sun, water and oil. After several months or years, a vegetable tanned product can acquire a rich unique patina that is strikingly different from its new appearance.
There are many commercial leather conditioning products available, as well as natural animal oils such as mink oil and neatsfoot oil. Store-bought leather conditioners will clean and add luster. Animal oils may darken the leather considerably. Be careful though - continuously saturating leather with too much of any oil will weaken the leather over time and make it prone to tearing. Vegetable tanned leather can be lightly cleaned and conditioned by buffing briskly with a soft cotton or linen cloth. This friction slightly heats the leather and brings its natural oils to the surface.