Smoke-tanning, also known as brain-tanning, is the most ancient method of not only hide tanning but of textile creation worldwide. It is the only hide tanning method found around the globe, in every corner of the world. Since it can’t be reproduced in a factory setting, smoke-tanning always happens on the home and community level.
Smoke-tanning + Brain-tanning are so named because these textiles are created through a combination of fat and smoke. The fat (in the form of, yes, brains) absorbs into the hide to lubricate the skin fibres, while the smoke organically reacts with the fat molecules and transforms the hide from skin into fabric. A hide must be worked vigorously with tools and by hand to turn it from a stiff piece of rawhide into a smooth cloth that is softer than any cotton blanket. The smoke-tanned courses offered by Fern + Roe use European techniques, mainly in traditional Scottish methodology.
Over the centuries, Bark-tanning was innovated to create leather. By taking rawhide and buckskin, and mixing them with bark and plants, tanners created a new textile. This mixing act extracts the plant cell constituent, tannin (tannic acid). Tannins transform a hide into leather by reacting with the skin proteins on a microscopic level. A hide will literally turn from skin to a red leather right before a tanner’s eyes. Bark-tanned leather became the foundational craft needed for weaving, by providing structure for looms, and many other folk crafts. It also became the preferred tanning method in the urban English world over the past 5 centuries, so much of the historical record speaks to leather production, leather guilds, and bark-tanning influence on other folks crafts.
Bark-tanned leather gets us sturdy objects like bags, saddles, belts, and hiking shoes. Natural leather can also be made into a soft fabric, similar to buckskin (chamois) but with greater water resistance.
Mineral Tanning also creates leather, but through a different ingredient list. It utilizes the mineral alum (aluminum potassium sulphate) to create a bright-white leather, and when mixed with other minerals new textures, colours, and depths can emerge. Alum is also used in naturally dyeing as a mordent, and this make alum-tawed leathers perfect for making bright, colourful textiles.
While Smoke-tanning and Bark-tanning are worldwide hide tanning practices – due to the presence of fat, smoke, and plants globally – Mineral tanning is denizen to specific geographies where alum and other minerals are found in high concentration in the soil. This includes Eastern Europe, SWANA, and South Asia. Mineral Tanning is also found where minerals form encrustments (outcroppings), which tends to be dry climates but is even found in northern Scotland. Its practice evolved with the evolution of sheep tending and it is currently used mainly for fur-on leathers, though its smooth white leather had a major impact on the historical Silk Road trade route.
Simply put, Rawhide is a dried hide. There is more to this story, though. Skin acts like a textile once it has been dried, so Rawhide can be used in a variety of ways to construct a product of object of desire. It can be taken when wet to form a particular shape, or dried flat and then cut out. Rawhide has been made into anything from containers to horse bridles to shoes to windows. Most famously, it is the textile placed on drum heads, to give them their deep and expansive resonance. Rawhide is the original cast material used to set bones, applied with the principle of using it when wet to form it into the shape one wants. It is a natural canvas and can be made into a bright white backdrop for painting.