Design & Make

A Walkthrough of Leather Tanning

by Aurora Almendral June 07, 2018
ReadA Walkthrough of Leather Tanning

Leather can be strong or supple; it can drape languidly or provide structure. The memory of the texture stays with your hands, and the earthy fragrance reminds you of its closeness to nature. It responds to the curves of your skin, and grows in character and beauty with age. Fine leather is mesmerizing, and Nick Horween of the venerable Horween Leather Company in Chicago, helped us understand how this incredible material is made.

Leather is not simply the skin of a dead animal. It is a material made through a multi-step process by skilled tanners in a craft that goes back at least 5,000 years. In the ancient world, formulas were whispered from father to son, and trade guilds of the European Middle Ages protected the secrets of the process. Tanning is not undertaken lightly. It takes experience, as well as a dedication to quality, to produce the kind of leather that deserves to be revered.

It is hard to marvel at a pair of stately wingtips, or turn your grandfather’s wallet over in your hand’s and understand why they feel richer and why the textures are more luxurious without understanding what goes into it.


Leather can be made of any type of animal skin. Ostriches, raccoon tails, goats, snakes and stingrays can all hope to be made into a shoe or a wallet but the majority of the world’s leathers are bovine cow, calf, or buffalo. The next two largest sources of leather are equally delicious: lamb chops and bacon, or as they are known in the leather industry, sheep and pig. Most commercial leathers, as you may have guessed, are a by-product of the meat industry. While it may be the imperfect stepchild of the ideal of using all parts of an animal, it is comforting to know that there isn’t a parallel industry supplying skin for leathers, and tossing out the steak.

Tanning, by definition, does not alter the original fibrous structure of the skin – good leather begins with a good skin. “We try to source as many of our materials as domestically as possible,” Nick Horween says, “We do get better “selections” from some hide suppliers over others, so we buy as much as we can from those specific brokers.” Horween’s cowhides come primarily from North America – Iowa, Illinois, Nebraska and Canada – while the horsehide supplies come primarily from France, as well as Quebec and Belgium, where horse is more likely to turn up at the meat counter.

The skin is cured to prevent putrification during transit from slaughterhouse to tannery, then processed to remove hair and any remaining flesh. There is liming and de-liming, bating, washing and pickling before the hide is ready to be tanned.


The purpose of tanning – regardless of the technique – is to alter the protein structure of raw animal skin, preserving it from decay and turning it into the material so beloved the world over. A nice soak in tanning liquor, an astringent solution of carbon-based tannins or mineral compounds, is what keeps your oxfords from rotting straight off your feet.

Industrial tanning uses two basic methods that produce different leathers suitable for different uses. In the hands of a skilled tanner with recipes for a good tanning liquor and opulent finishing oils, both vegetable and chrome tanning can produce leathers of transcendent quality. Hurriedly done, however, a vegetable tanned hide can crack and peel, and a poorly made chrome tanned leather may as well be pleather.

Chrome tanning, the relative newcomer to a millennia-old craft, was developed in 1858. Hides are tumbled in drums with a solution of metal chromium, a naturally occurring ore. More than 80% of the world’s leathers are chrome tanned, and varieties within the technique produce different leathers suited to a wide range of uses, from goods as rugged as hiking boots, to adornments as delicate as a pair of ladies’ Neapolitan gloves. The popularity of this method results from the speed of tanning and the versatility of the finished skin.

Hemlock, oak bark, mangrove, millet, birch, larch and pine, as well as extracts from mimosa, and sumac are used in various combinations and proportions for vegetable tanned leather. The older of the two methods, “vegetable tanning is the “old world” technique”, Nick says, and it produces thick, malleable leathers, which are more limited in use. The hides are soaked in a series of gentle vegetable liquors, a slow process that, when done right, results in the firm, even leathers of sturdy shoes and hand-tooled saddles.

Horween’s signature Shell Cordovan is the only genuine, straight vegetable tanned cordovan still produced in America. Much more than its deep burgundy shade, real Cordovan leather is cut from horse hide and is the result of loyal adherence to a process that was first developed by the Moors of medieval Cordoba, Spain. “Cordovan takes six months,” Nick explains, “two separate tannages of thirty days each, and ninety days rest after being hand-oiled.”

Combination tanning uses both processes – an initial chrome tanning, and a retanning with vegetable liquors. The majority of Horween’s leathers, including the popular Chromexcel, are tanned using a proprietary formula, and hot stuffed with their own secret recipe of smoothing fats and oils. “Combination tanning is a great method for producing leathers because it allows us to take advantage of the varying benefits chrome and vegetable tanning provide. Chrome tannages generally provide soft, supple and very durable leather. Vegetable tanning yields leather that is easier to shape and feels more ’round’ when in the hand. By combination tanning, we are able to produce leathers that mold well and feel great to the touch.”


Tanning, Nick says, “is a combination between science and cooking,” as anyone who has come up with slop at the end of a Julia Child recipe knows, getting something right is more than just following directions. “We always start with the best raw materials; for example, food grade beef tallow, cosmetic grade beeswax… products that you probably wouldn’t see in the vast majority of tanneries. The main emphasis here is the skill required to make leather, and our workforce is the most important component of our process. We have many employees that have been with us for 20, 30, even 40 years –  there’s no substitution for that kind of experience.”

The Horween Leather Company was founded by Isadore Horween in 1905, and the company and its techniques have been passed down through five generations, making Horween one of the oldest continuously running tanneries in America. To put it in perspective – Horween is a contemporary of Ford Motors and its mechanized assembly line. Horween achieved its stature in the same century that outsourced nearly the entire American manufacturing sector and produced the national ethos of bigger, faster, cheaper. Horween’s success in such an improbable century is testament that dedication to producing the best has no substitute.

Don your best leather and other material wares with items from the Accessories Collection.


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