Zen Grain

Leather is not leather. I mean it is leather in the sense that it is hide from an animal prepared for use. After that all bets are off. Did you ever notice how different wallet, shoe, car seat and jacket leather are?

These differences come from the type of hide and tannery processes. In most cases the animal that the hide was removed from isn’t the largest factor in the material’s properties. This is not an authoritative guide but instead is composed of gleanings.

Basics

This is a summary of the production process so the following leather types make sense, not a detailed description.

Prep

The hide arrives and the hair is removed and the inside of the flesh is trimmed to a somewhat reasonable even thickness for handling. The hides are washed and often stretched. Then the hide is treated with chemicals to help remove unwanted proteins and oils (liming). Hides are then often bleached to yield a lighter or more even color. Then the pH (acidity/alkalinity) is modified for the tanning process (pickling).

Tanning

The leather then goes through the actual tanning process. Most common in order are chrome, vegetable, aldehyde and alum. Some leathers are re-tanned, typically with a different form of tanning. This usually takes place after further processing of the hide, but could be done back-to-back with the original tanning.

Treatment (crusting)

This encompasses a variety of steps after initial tanning but before finishing (if finished). Splitting, dying, re-tanning, graining (or grain correction), filling (for hardness/density), stuffing (with waxes/oils), conditioning, and softening are some additional steps to prepare a hide.

Finishing

This includes steps to finish the surface and can include physical processes like flattening and embossing as well as chemicals to coat, seal and protect the surface of the leather.

Grain

Often the ‘top’ surface of a piece of leather isn’t the originally exposed skin (hair side) of the hide. A significant amount of leather is cut from below that outer surface. Often it looks like skin because the split surface was pressed and embossed with an artificial grain. In some applications this fake but controlled grain is desirable for surface feel or appearance.

Terms

• Full grain: the original outer skin.
• Top grain: anything which includes some of the original outer skin.
• Corrected grain: modified outer skin. Imperfect spots sanded and imprinted to look like grain.
• Re-grained: basically corrected grain for the whole hide.
• Nubuck: top grain that has been buffed to a velvety texture.
• Split: anything which is cut from beneath the top grain. Often grained and finished to look like top grain.
• Skiver: basically the same as a split, but often thin or uneven, and rarely grained.
• Suede: essentially a Nubuck made from a split. Due to the difference in fibers from top grain, suede can be fuzzier than nubuck.

temper

Temper doesn’t have an official standard, but refers to industry short-hand about the flexibility/rigidity (floppiness) of the leather. “The resistance of light leather to bending and the extent to which it recovers its shape after bending” ¹. Soft temper is like soft fabric and firm temper is like firm card-board. These terms are used relatively and subjectively in the industry.

Color and Dyes

There are really two categories of coloring of leather: those that penetrate and those that sit on the surface. The earlier are typically what is referred to by a dye, and the latter is basically paint. Industry usage adds a layer of complication with the type of dyes, such as aniline. Further terminology exists such as mill dyed, drum dyed, through dyed, etc.

Types of leather

These are some common names you’ll see for leathers. It is not empirical or complete but based more on (U.S.A. and Anglophone) markets. Australia has additional names for leather treatment. Names have morphed in the history of western (euro-american) leather use. In some cases background is given, but the descriptions are based on modern commercial usage.

• Rawhide: Untanned but usually treated hide. “Limed, often stuffed with oil and grease.” ² Most rawhide is offered in thin <6oz thickness for stretched projects like drum heads.
• Latigo: typically refers to a chrome tan, veg retan. However, a major US manufacturer (Hermann-Oak) makes an all veg tan, hot-stuffed and waxed leather that is sold as latigo. ³ The IS 1640:2007 is quite vague: “Strong leather used extensively where strength and body are desired.” ⁴ Latigo is usually aniline dyed, or otherwise on the hide side, not through-dyed. Horween’s latigo is chrome tan with “heavy” veg retan and fat-liqoured and pasted. ⁵ Wickett & Craig’s latigo is “hot dipped” in wax and oil, and available in two tempers. ⁶ Chahin even offers an ‘Alum Latigo’ in addition to their traditional latigo. ⁷ The two-step tanning process was originally developed to fully tan shoe leather. The veg tan process took too long but the properties of veg tan were required.
• Bridle: Often ‘English’ bridle, as it was preferred in Britain and widely used in saddlery. Veg-tanned, heavy, firm and very waxy. Will take some tooling but won’t mold/form. Grain is typically very smooth, and the leather is through-dyed. The flesh side is usually smoothed and finished. Some tanneries offer separate regular and English bridle.
• Harness: “Harness leather is similar to [...] bridle leather but offers full thickness.” ⁸ Most harness leathers are less waxy on the surface and use more tallow. Often available in greatest thickness, sometimes unsplit (unskived) from the original tanned hide. Some is left in a natural state with tanning and tallow coloration, others are drum dyed. Flesh side not as smooth and finished as bridle, and the grain side is often a heavier, less-even texture with natural hide tone variations visible. Typically a firm strong leather. Will take some tooling but won’t mold/form. Harness hides typically run large as the application calls for long strips, hides from bison, buffalo or ox common, but much on the market is cow.
• Strap: Also called holster or tooling. Veg-tanned less ‘stuffed’, oily or waxy, and takes tooling and molding. Finishing doesn’t prevent oiling, dying or forming, but isn’t water resistant like bridle and harness. Often un-dyed.
• Skirting: “Skirting displays similar characteristics to our classic [strap and] tooling leathers.” ⁹ Similar to strap in that it will take tooling and molding, but typically thicker. Traditionally it isn’t dyed but most tanneries offer through-dyed. Since saddle leather isn’t seen on the flesh side it is usually unfinished.
• Sole: Often ‘sole bends’. These are tanned for use in the soles of shoes. Veg-tanned and very thick and hard. Most are plain color, and lightly finished. Some will have some conditioning but tends to be drier leather.
• Pull-Up: This describes a wide variety of leathers that share a characteristic. The surface is finished in such a way that handling, particularly creasing and scratching, wears away or changes the density of dye or pigment. The term derives from the original leather which was a nubuck or light suede that was waxed smooth. As the finished wore the leather fibers would literally pull up. However, smooth top grain can have the same finish without the texture. Some pull-up leathers have a mix of dying and pigments so that the worn look is controlled.
• Upholstery: Mostly chrome-tanned and finished for furniture, automotive, or marine use. There is a wide variety of tempers, dyes, and finishes. Typically thin and flexible compared to veg tan and saddlery leathers. Often available in full hides. Typically grain corrected, re-grained or split.
• Garment: Mostly chrome-tanned and light weight for clothing and bags. Suedes and nubucks are common.
• Napa: An untanned treated leather patented (US165348) by Emanuel Manasse in 1875. Soft and strong, it is often used for gloves. Rare to find true Napa anymore. Nappa is a bastardization of the spelling of Napa county, in which the tannery Emanuel worked for was located. It often refers to chrome tan leather than is treated to emulate Napa leather.

US Tanneries

As far as I know there are only three U.S. tanneries producing veg tan leather:

• Hermann Oak: All leathers produced are veg-tan.
• Wickett & Craig: All leathers produced are veg-tan.
• Horween: A mix of veg tan, chrome tan with veg re-tan, and other custom re-tanning. The cordovan and Essex line (Derby, Dublin) are listed as straight veg-tan. Horween’s website is somewhat confusing so I recommend their direct-sales site: The Tannery Row.