Natural Grain Leathers
This group includes leathers finished with their grain intact. The leathers suitable for finishing of this type should be of good grain quality without deep scars or looseness.
Full Aniline leathers
Full aniline leathers should have no covering material used in the finish coat. The leathers are dyed into a color close to the required color. Two to three coats of transparent finish with or with out dyes is applied. This finish serves as a protection to the grain surface.
Special type of milk protein based binders can be used to finish this type of leathers. These binders can be subjected to high temperature by friction in glazing machine to give a brilliant glossy look to the leather surface.
These types of finishes enhance the natural appearance of the surface and highlight variations present. The quality of raw hide, dyeing and other processing should be of very high standard.
Semi Aniline leathers
Semi aniline leathers are next in the value order. Finish mixes contain relatively small amounts of finer variety of pigments (about 4 to 7 percent in solution) along with dyes. They can be finished using protein binders and glazed or using resin binders which can not be glazed.
The pigments used in the finish can cover up minor scratches and superficial scars. Variations in dyeing can not be covered up.
Imitation Aniline leathers
Imitation aniline effect is obtained by first applying finish coats with high amount of covering material (over 10 to 15 percent in solution) first and then coating with transparent mixes containing dyestuffs.
The bottom coat covers up the defects and variations on the surface, thus the natural grain look is lost to some extent. The top dye coat gives the brilliant aniline dye appearance to the surface.
Pigment Finished leathers
Pigment finished leathers are those types which are finished with relatively high amounts of covering material. Due to cost reasons dyes are not used or used sparingly.
The covering of defects is very good in this finish. However, if the crust is not tight enough it may lead to looseness.
Imitation grain leathers
These types of leathers are made from relatively poor quality hides. The hide surface has a number of deep scars and can not be finished to a uniform look without modifications. Typically, the grain is removed by buffing, special resin binders are used to reduce the looseness of the grain layer and heavy finish coat is applied to get an uniform finished surface.
Corrected grain leathers
The crust is buffed to remove the top grain pattern and treated with a filling type of resin binder, which makes the grain layer tight. Afterwards, several coating of finish mixes with high amount of covering material are applied. Often, an artificial pattern similar to the animal grain (hair-cell prints) is applied using metal plates under heat and pressure (in hydraulic press or roller presses).
The finish can be modified to obtain different end results such as glossy surface, dull surface, waxy surface etc. and the surface is relatively uniform. Leather loses its natural appearance. Special effects such as brush off effect can be obtained by using suitable binders and coloring mixes.
Printed Leathers
These leathers are finished similar to corrected grain leathers, but with a deeper print on the surface. A variety of print patterns such as crocodile print, lizard print etc. can be applied.
Hides of low quality can be used as the surface is entirely replaced with an artificial pattern. Leather strength and natural quality are lost. These leathers are used mainly for making leather goods (wallets, bags, belts etc)
Finished split leathers
Normally, due to the coarse and weak fiber network, split layers can not hold the finish coating well. However, some special techniques can be used to apply finish coatings on the split surface usually with some printed patterns.
These are made from the lowest grade hides, which can not be finished in any other manner.