In leather goods, the grade and quality of the end product are largely determined by the type of leather grain used. At a high level, leather grain can be categorized into two main categories of leather — "fewer imperfections", and "lots of imperfections."
One common misconception with real leather is what the different grades of quality actually mean. Much of the confusion can come from the way that these leather types are referred to, like how “top grain” leather to the outsider might seem like the highest quality of leather when it’s actually only the 2nd best grade of leather behind full-grain leather.
The 5 Types of Leather in order of their quality level are:
1. Full-Grain Leather
The highest quality of grain found in leather as it's closest to its natural state. It’s an incredibly strong type of leather and has patinas that will develop beautifully with age.
2. Top-Grain Leather
The second highest quality grain of leather after full-grain leather. It's easier to work with than full-grain leather and is also used in bag making. Top grain leather has a sanded surface where the leather’s outer layer is sanded to remove imperfections found in the hide.
3. Corrected Grain Leather
A medium grade leather grain. It is fully sanded down and an artificial grain is added for aesthetics. Because of the extra layer of added artificial grain, it can be made in a variety of colors and finishes.
Considered a low grade of leather since it’s actually derived from parts of top-grain leather that are split (the fibrous part). This splitting process can be done numerous times (hence its name) depending on the thickness and quality level desired.
5. Reconstituted Leather
The lowest grade of the five types of leather, reconstituted leather is made from scraps of other types of leather-like top-grain or corrected grain leather and binding them with latex binders to simulate the appearance of genuine leather.
With the ISM backpacks, we chose to use full-grain leather as it's the highest quality of grain found in leather since it has the least number of imperfections.
Full-grain leather is made from animal hides that haven't been treated yet via sanding or buffing. Because it isn't trimmed or shaved it's a type of leather that's closest to its natural state, making it durable for long term use.
Compare this to other types of leather, like top-grain leather that's taken from a layer of animal skin that contains lots of uneven marks (grains and corium). Because of these imperfections, top-grain leather goes through multiple layers of sanding in order to remove the marks to give it a smooth hand feel. Other lower grades of leather-like Split Leather are even made up of a mix of real leather and synthetic leather (PU), which makes it cheaper to produce and less durable.
We wanted to use leather that would last (it's why we stand behind our lifetime warranty) so full-grain leather is a perfect fit. It’s an incredibly strong type of leather and has patinas that will develop beautifully with age and is less stain-resistant than other types.