The beautiful piece of leather that covers your sofa or chair had a long journey to travel to get there. It began as the hide of an animal, usually a cow, bull, or steer. Skinning the animal was the first step after slaughtering for meat. After the hide is removed from the animal, as much fat and flesh must be removed as possible, as these will decay and spoil the tanning process. The hair must usually also be removed at some stage. As an untreated hide, called rawhide, will rot, it must be treated in a number of different ways to preserve it.

To begin the tanning process, it is necessary to use salt to cure the hide. The salt will stop the bacterial decay and help ready the hide for the next step, which will involve removing the hair and help to dissolve any remaining fat or grease. Milk of lime and various sulfides are used in this step of the tanning process. After this has been done, the hide will have its hair taken off by mechanical means. Any remaining hair will have to be removed by hand. The exception to this, of course, will be Hair-On Cow Hides.

It is now time to begin the actual tanning process, which will be accomplished in one of two ways: vegetable tanning or mineral tanning. A third process, called tawing, is not actually tanning and is generally used to cure pigskins and goatskins. Tawing does not really tan the leather and if subjected to prolonged moisture, leather prepared by this method will eventually rot.

In vegetable tanning, tannin is actually used. Tannin is where the term ‘tanning’ comes from. The old German word for oak was tannin, and it was the bark of the oak that was originally used in tanning. Today, tree barks from a variety of sources are used to obtain tannin; besides oak, hemlock, chestnut, and mangrove barks are also used. The hides to be used in vegetable tanning are stretched then put into a tannin bath for several weeks. Hides prepared in this way tend to be somewhat stiff. Leather prepared by vegetable tanning is often used for leather upholstery.

Mineral tanning is a much shorter process and will take the hide from the cured stage to leather in only one day. Chromium sulfate is used in mineral tanning and the chrome is absorbed into the leather to stop any process of decay. It also renders the leather quite soft and suitable for clothing or handbags as well as upholstery and cowhide rugs.