Beyond color and appearance, there are functional differences between leather types that can help you decide which to choose for your project.
As a natural material, hides are not uniform in thickness. At the tannery, hides are run through “splitting” machines, which attempt to even out the thickness of each skin. The cut material from the flesh side of the hide is called a “split,” and is sold as an inexpensive leather product. Leather thickness may be measured in ounces (for imperial measurement systems) or in millimeters (for metric systems). Most hides are classified by the top two thicknesses measured in the skin, so a hide that is sold as “7–8 ounce” (2.8–3.2mm) will not be any thicker than ⅛ inch (3.2mm). Select a hide in a thickness that is suitable for your project; thinner hides provide more stretch but less structure, while thicker hides provide more rigidity but are less forgiving.
Flexibility and Stretch
Flexibility and stretch are partly determined by the thickness of the leather, and partly by the location of the leather on the hide. Different areas of the hide have different fiber structures.
Bellies (the sides of the hide) have a spongy, loose fiber structure, the most uneven thicknesses, and the most stretch—and are thus the most inexpensive.
Butts (the bottoms of the hide) are the most sturdy and strong, with a tight fiber structure—and thus the most expensive.
Shoulders (the tops of the hide) are somewhere in between bellies and butts, with a medium stretch and medium structure. Shoulders are a good place to start for beginning leathercrafters, striking a balance of cost and structure.
Leather is an expensive material and leathercrafting is time-intensive work, so you want to make sure that you select leather that will look good for years to come for your particular project. When deciding which type of leather to use, think about whether the project is going to be used indoors or outdoors, and whether it will be used in wet conditions or in dry conditions.
Garment leather fades in the sun, while oil-dyed vegetable-tanned leather darkens in the sun. Some garment leather is treated with a waterproofing coating.
Vegetable-tanned leather holds up well in outdoor conditions, but may need regular maintenance.
Bridle leather is infused with dyes, oils, and waxes designed to stand up to all of the rigors of sun and rain, but may be an unneeded expense for indoor use.