Basic Overview of Leather Grains and Qualities
Leather is made from a variety of animal hides. The hides are preserved through a process called tanning, during which a chemical (tannin) is usually applied to the hide. Many methods of tanning have been developed over the centuries.
The most common tannins you'll hear about these days are vegetable-based, resulting from the bark of trees, wood or other plant parts, or chrome-based, where chromium salts are used. Other types of tannins exist. Color imparted to the hide during tanning varies depending on the process and tannin used. Dyes and pigments are often applied to leather later in the production process.
After tanning, hides may be split to obtain a material that can be crafted into useful products or apparel. If the top surface of a hide is of exceptional quality, meaning that it does not have much damage from insects, scars or brand marks, then it can be used as-is and is called full grain leather.
Full grain leather is the best quality of leather. Because it has not been separated from the top grain or split layers, it is the strongest and most durable leather. The grain remains intact, and the pores and patterns of the hide can be seen. As an example, pigskin leather is known for its deep hair follicle pattern, while buffalo leather is known for its pronounced patterning or sometimes pebbly appearance. Full grain leather is the most breathable type of leather, so you'll often find it in boots and saddles. When properly cared for, this type of leather will wear for a long time and develop a rich patina.
Top grain leather is made from hides that are considered to be too flawed to become full grain leather. It has had the split layer of the hide removed from it, leaving it softer and more pliable than full grain leather. The leather is then sanded or buffed to remove flaws. It may have a finish coat added to the surface, making it less breathable than full grain leather. The name "top grain" often confuses consumers as it makes this type of leather seem to be the "top quality." In fact, it is not the highest quality of leather-full grain leather is. The grain in this type of leather may be "corrected," where imperfections in the hide are removed through sanding. Then an artificial grain is pressed into the leather and topped with a treatment of pigment or stain. Top grain leather is also used to create suede and nubuck.