Making Leather

Leather is one of the few materials that mankind got right pretty much first time. At some point in in the Neolithic era, our ancestors discovered that steeping animal hides in a liquor of water and tree bark prevented them from rotting. This process – tanning – is one of the oldest methods of creating a usable material known to humanity.
Cows or sheep, camels or crocodiles, snakes or eels… the skin of any creature can become leather. Once the fat and protein have been removed from between the collagen fibres, the skin has been dehaired by soaking in lime, then stretched and dried, you have rawhide, a strong and durable material, but one which will begin to rot when exposed to water for prolonged periods. Tanning prevents this by stabilising the collagen; the tannins bind irreversibly to the fibres, making the resultant leather immune to microbial attack, and therefore to the actions of decay.

This process is still practised, largely unchanged, today, although a number of other methods of preparing leather have also been developed, including alum tawing (in which hides are treated with aluminium salts); oil or brain tanning (where hides are tanned in brain fats to make buckskin leather); and chrome tanning (in which chromium is used as the tanning agent instead of tree bark).

Most of the world’s tanneries now employ chrome for the sake of efficiency, but the majority of the leather used by the Bill Amberg Studio is produced by traditional vegetable tanning. This process may not have the uniform result or rapid turnaround time of chrome tanning, but the leather that it creates is extremely sympathetic to work with, versatile, rich in both textural and visual character and has the capacity to evolve over time – ideal for the creation of luxury products, unique accessories and welcoming interiors.

Types of Leather

Leather is a material of astonishing variety, available in a vast array of colours, sheens, sizes, weights and textures. The look and feel of a piece of leather is the result of a number of different variables, each of which is taken into consideration depending on the qualities required of the final product:

The Tannage


In vegetable tanning, the type of tree barks used will affect the natural colour of the leather that results. This is why in Britain, which had a strong and long-standing tradition of oak-bark tanning, our leather is known for its rich dark colour, whereas in Spain, where mimosa bark is more commonly employed, the leather generally has a lighter, more orange tone.

Although there are numerous trees and plants that can be used for tanning, today most vegetable tanneries draw on four main tanning agents: mimosa (aka wattle), which gives a pinkish hue and is often used for soles; chestnut, for heavy leathers; the South American hardwood quebracho, which both acts quickly and enhances durability, and the tara plant of Peru and North Africa, whose fruits contain highly concentrated tannins that have only a delicate effect on leather colour. Depending on the desired effect, the tannery will generally use a combination of agents, tweaking their recipe according to the aesthetics and function of the leather they want to create.

The Bill Amberg Studio works with a tried and tested group of tanneries across Europe, sourcing the right leather for the application in hand.

The Animal Itself


Because leather is an organic material, one of the most significant determinants of the properties of any given piece is the species it came from and the life the animal lived. As well as the obvious differences between, say, a cow and a camel, other more subtle factors can have an impact, such as age, breed, and diet – even the climate of the place it was from. And of course, the type of animal is what dictates the size of the hide in the first place.

Many parts of the world are known for producing particular kinds of animal leathers. Which leathers they specialise in is dependent upon the regional diet. Leather is a by-product of the food industry and tanneries work with the hides they have available; hence, the beef-eating nations of Northern Europe produce heavy cattle leathers; Italy, which produces most buffalo mozzarella, likewise makes most buffalo leather and France, where veal is a butcher’s staple, crafts excellent-quality calfskins.

The Dye


Leather can be dyed in any colour, most commonly using soluble aniline dyes to retain the appearance of the grain. Full aniline leather is the softest, most natural looking and most exclusive, but because it lacks any protective coating is defenceless against staining or the fading caused by prolonged exposure to light. Semi-aniline leather is similar, but has a protective topcoat.

The Part of the Hide


A single hide can be divided into several areas, each of which may be suited to a specific application. Leather from the rear or butt of the animal (which can in turn be divided along the line of the spine into bends) tends to be thickest and strongest, making it ideal for belts or soles and heels in shoemaking, for instance. Belly leather is softer and stretchier but less durable and only offers a relatively small area to work with. The most versatile and characterful is perhaps shoulder leather, which Bill Amberg uses in making bags, accessories, walls and floors.

The Grain


Hides can be laterally separated in several ways to create various leather types, each of which has different properties. Full grain consists of the top layer of the hide, and maintains its natural grain, without being sanded or otherwise treated (abrading the surface to create a velvety finish gives you nubuck). Full grain develops a patina over its lifespan, acquiring character as it ages. Top grain also comes from the uppermost layer, but is sanded and finished, making it more pliable and stain-resistant than full-grain, although it does not change with age. Softer but weaker and less water-resistant, Split leather comes from the lower part of the epidermis, beneath the grain, and, when buffed on the flesh side, becomes suede.

Crafting Leather

For as long as there has been leather, there has been leathercraft. Techniques for manipulating leather have been honed over millennia, but have changed very little during that time. What the Bill Amberg Studio does today is essentially the same as what Neolithic man was doing many thousands of years ago – it’s just we’ve developed a few better tools and expanded our understanding of what leather can do as a material.

The raw material for leatherworking is the tanned hide, which, before finishing and dyeing, is known as the crust ­– a single, stable piece of dry hide that can be stored easily and then rewetted, stretched and manipulated as necessary. (The chrome-tanned equivalent is called a wet blue, so named for the colour it acquires from the chromium and the fact it needs to be stored moist).

The skills of leatherworking can be broken into four artisanal craft disciplines: bookbinding, casemaking, saddlery and shoemaking (or ‘books, bags, bridles and boots’). Each of these has its own tools and traditions for cutting, moulding, hand stitching, stamping and embossing leather, according to the demands of their trade.

In our work at the Bill Amberg Studio, we take advantage of the skills and principles behind all of these crafts to explore the possibilities of leather and new ways to apply it to objects and interiors. That’s why you might spot the bookbinding techniques in the wet-moulded folds of a leather wall panel, notice the unconventional use of shoe-sole leather in one of our stools, or identify a traditional hand-sewn saddle stitch on a Bill Amberg bag strap. It’s through drawing on the ideas and expertise of the past that lets us innovate for the future.