All leather goes through the same process of preparation and tanning. Only high-grade leather is tanned for long enough (10 to 20 hours) to ensure that all of the oils and added cleaning agents are removed from the hide. Low-grade hides are only tanned long enough (one to nine hours) to remove surface coatings of oil and agents.
The grade of a leather piece is determined by how it was prepared for use in creating the product. Shortcuts in the tanning process and the use of flawed hides are the main difference between low-grade leather and high-grade. Assembly of the leather piece can also determine the grade.
High-grade leather is selected for the blemish-free appearance of the top and back surfaces of the hide. Low-grade leather will sand, grind or buff blemishes from the surfaces so they are less apparent. This removes a layer of the hide and makes it more prone to cracking from moisture penetrating into the hide.
Hiding the Blue
Before a hide is tanned, it is treated with agents that turn the hide blue. High-grade leather has been tanned long enough to remove all the agents and all the blue coloring from the hide. Low-grade leather is still blue in the center. This bluing is often hidden by edging the low grade leather so it can not be seen. High-grade leather is usually not edged to show that there is no blue in the center of the hide.
Grain refers to the topmost layer of the hide. On high-grade leather, the top grain layer may be separated from the lower grain and combined in swatches to create a piece that is wholly top grain. These swatches can be layered to create a thick piece of leather that is off a consistent grain quality. Low-grade leather will often bind two pieces of top grain over a lower grain to create the illusion of a thicker piece of high-grade leather.
- Photo Credit Thomas Northcut/Photodisc/Getty Images