The Fascinating Process of Leather Production and Procuration

Leather. We tend to take it for granted, but a lot of us don’t really think about where it comes from. Whether we use it to make shoes, jackets or, of course, chairs and sofas, leather is a durable, versatile, and attractive material.

Where does Leather Come From?

Technically, leather can come from any animal, but the vast majority of leather we use comes from cows. Most sheep hide is turned into sheepskin, with the wool left on for padding. Pigskin is also commonly used to line shoes and to make wallets, bags, and gloves. Furniture is generally, though, upholstered with leather from cows.

Leather comes, primarily, from animals that are also used for meat. It has been used for thousands of years, although prior to modern agriculture a much wider variety of animals was used. Hunter-gatherers used the skins of whatever animals they could find, and tests have shown leather coming from everything from squirrels to alpacas. Now, though, almost all leather comes from industrial feedlots and dairy farms.

How is Leather Made?

Leather is made by a process called “tanning.” In Medieval times, tanneries were located a bit away from residential areas and downwind. The tanning process is quite, shall we say, pungent. Traditionally, human urine, collected in chamber pots and taken to the tannery by a nightsoil man was used. This is why some European towns have a street or even a neighborhood called “Tannery” or “Tanneries” to this day.

Nowadays, we no longer collect the contents of people’s toilets to tan leather. Instead, we use either trivalent chromium or tannin extracted from tree bark.

Vegetable tannins are generally used to produce heavy leathers, such as those used for soles or upholstery. Chrome tanning is used for lighter leather, things like jackets, pants, gloves, etc. Both essentially do the same thing, however; they apply tannic acid to the hide to prevent it from rotting, make it more water-resistant, and keep the hide supple and durable. Collagen fibers in the hide react with the chemical agent.

From the Farm to the Beam House

When the hide arrives at the beam house, it is inspected, graded and then trimmed. Then it is soaked to remove the salt used to cure it and restore the removed water.  At this point, the fate of the hide is determined, depending on its quality, thickness, and what animal it came from.

The tanner then ensures that the hide is of uniform thickness. It is then de-haired. This process, generally done by liming, removes any remaining hair from the follicles. The hides are put in a pit or drum containing calcium hydroxide and sharpening agents to loosen any hair, then scraped. In most production facilities this is done by machine, but it can be done by hand in smaller operations.

Once the hair is removed, the hide is bated by being soaked in a warm water solution of an ammonium salt and proteolytic enzymes. This also removes any residual lime. Hides destined for chromium tanning may be pickled in brine.

At the Tanyard

The hide then goes to the tanyard, where it goes through a different process.

1. For vegetable tanning (most upholstery), the tanning materials are added slowly over about three weeks. Then the hide is wrung and cropped then inspected. Some very heavy hides may have to be re-tanned and scrubbed.
2. For chrome tanning, the hide will have been degreased, but the other steps are the same. The hide is pickled to drop the pH to 3 or lower, then put in a bath with a trivalent chromium salt and the pH raised. Afterward, the leather is graded, split, and shaved to the final thickness.

Afterward, the hide is wrung and split. Splitting removes the flesh side of the hide, which then goes to a split tannery for re-tanning. The remaining hide is then shaved.

Chrome tanned hides are often bleached and colored at this point rather than being dyed later. They are also then fatliquored to replace the oil lost during the tanning process. Chrome tanned hides are intended for softer uses (the vast majority of leather is chrome tanned).

Finally, the leather is dried. The most common method is simple air drying, just like the clothes on your line. In some cases, the leather may be dried in a controlled environment, and a vacuum is sometimes used. Some tanners even use electromagnetic fields. These are all done to speed the drying process, but air drying remains very popular.

Leather Finishing

Some leather is sold unfinished to shoemakers, clothiers, even to hobbyists. At some point, however, the leather will be finished. There are a variety of things which may happen to leather at this point:

• Conditioning
• Dying or staining
• Embossing
• Buffing. This is done with fine abrasives to produce the characteristic rough surface of suede.
• Lacquering. Patent leather is lacquered with urethane to produce the shiny surface
• Waxing and shellacking. This is done to create the smooth finish of most leather

What happens during the finishing process depends on the ultimate fate of the leather. Shoe leather is likely to be waxed and dyed, whilst leather used in harness making is often embossed.

The entire process from a fresh hide to a finished product can take anywhere from one month to several. Leather is durable and versatile, but it takes a lot of work to get it that way. At least we aren’t having to make sure we don’t get downwind of the tanneries anymore!

To find out more about leather and our wonderful leather seating in Tampa, contact Florida Leather Gallery today.