THE FOUR TYPES OF LEATHER
Full-grain leather refers to the leather which has not had the upper “top grain” and “split” layers separated. The upper section of a hide that previously contained the epidermis and hair, but was removed from the hide/skin.
Full-grain refers to hides that have not been sanded, buffed, or snuffed (as opposed to top-grain or corrected leather) to remove imperfections (or natural marks) on the surface of the hide. The grain remains allowing the fiber strength and durability.
The grain also has breath-ability, resulting in less moisture from prolonged contact. Rather than wearing out, it will develop a patina over time. High quality leather furniture and footwear are often made from full-grain leather. Full-grain leathers are typically available in two finish types: aniline and semi-aniline.
Top-grain leather is the second highest quality. It’s had the “split” layer separated away, making it thinner and more pliable than full grain. Its surface has been sanded and a finish coat added to the surface which results in a colder feel with less breath-ability, and will not develop a natural patina. It is typically less expensive and has greater resistance to stains than full-grain leather.
CORRECTED TOP-GRAIN LEATHER
Corrected top-grain leather is any top grain leather that has had an artificial grain applied to its surface. The hides used to create corrected leather do not meet the standards for use in creating vegetable-tanned or aniline leather. The imperfections are corrected or sanded off and an artificial grain impressed into the surface and dressed with stain or dyes.
Most corrected-grain leather is used to make pigmented leather as the solid pigment helps hide the corrections or imperfections. Corrected grain leathers can mainly be bought as two finish types: semi-aniline and pigmented.
Split leather is leather created from the fibrous part of the hide left once the top-grain of the rawhide has been separated from the hide. During the splitting operation, the top grain and drop split are separated. The drop split can be further split (thickness allowing) into a middle split and a flesh split.
In very thick hides, the middle split can be separated into multiple layers until the thickness prevents further splitting. Split leather then has an artificial layer applied to the surface of the split and is embossed with a leather grain (by-cast leather). Splits are also used to create suede.
This first category of leather finishes is reserved for the finest hides. Aniline dyes are tumbled in a vat with the hides, which permeate the leather. This produces a transparent, natural color and the full grain is visible. However, Aniline hides do not have any protection from fading or staining. Less common are wax and oil finishes of aniline hides. Leather finished this way is referred to as “pull-up leather” where the color changes as the leather is worn or used and stretched.
This leather finish is a combination of physically “distressing” the leather. For example, the process might include using a hairbrush and then applying wipes of pigment to produce an uneven color. The goal is to make an item look old or worn. Another way to distress leather is to spot it with water and then as it dries, it will shrink slightly giving it a pinched look.
Semi-aniline leather finishes are used on the next grade of hides. A sealant topcoat is added, which provides protection without losing the softness of the leather or hiding the grain. Semi-aniline finishes may also involve applying a pigment dye or metallic finish over the surface. Sometimes this type of leather finish is referred to as a hybrid finish. Most other leather finishes are applied by using pigment, heat, and mechanical means, or sometimes, the combination of all three.
Embossing leather consists of a process in which a design is added to leather by pressure as a way of altering or correcting the surface, resulting in uniform imitation grain. While embossing can add a decorative touch to leather, at times, this process can be used to disguise marks or scars. Typically, the leather would be pressed between a pair of dies that are designed to adapt to the hardness and depth of the leather. Then, a die is used to stamp the design into the leather while wet.