In its broadest sense, leather is any type of tanned animal hide. Different types of leather are characterized by both the type of animal skin used and the tanning and manufacturing methods employed. The most common types are made from cow hide, but leather from other animals, such as kangaroos and ostriches, is also popular in certain applications. Different leather varieties are suited to different purposes, including clothing, footwear, luggage, book binding, and drums.
An animal hide can be made into leather by a number of different methods, each of which lends different properties to the final product. Leather tanned with vegetable-based products is supple but can be damaged by exposure to water. Alum-tanned leather, created with aluminum salts, is less supple and can rot in water, but it can be made in much lighter shades than vegetable-tanned leather. A newer method of tanning, using chromium salts, results in a very supple leather that holds up relatively well in water. Brain-tanned leather or buckskin, made with animal brains or other emulsified oils, is washable and significantly softer than any of the above varieties, but it is also the rarest, as it is costly and time-consuming to produce.
Stiffer, more durable types of leather, suitable for use in drums, book binding, and, historically, armor, are created with different methods. Rawhide is made by scraping animal hide, treating it with lime, and stretching it throughout the drying process. Boiling in water or wax is another method used to make extremely tough leather.
The softer types of leather can be prepared in a few different ways. Full-grain leather, used in the finest leather products, is not altered past removing the hair and tanning the hide, so it requires raw materials of excellent quality. Top-grain leather is sanded on one side and given an artificial grain in order to hide imperfections in the raw material. The other side of this type of leather is fuzzy. Suede is fuzzy on both sides, as it is cut from the inside of an animal hide.
Other types of leather include patent leather, which has a very shiny, smooth finish, often coated with plastic; and shagreen, a rough leather usually colored green. Many special types are used in luxury products from gloves to pocketbooks. Belting leather is heavy and durable and can retain its shape exceptionally well. Napa leather is known for its softness, as is slunk, made from the hide of a calf fetus. Vachetta leather is typically used as trim on handbags.