When properly tanned, sheepskin is an excellent material for slippers, rugs, mittens, and many other items. But custom tanning or pre-tanned skins can be expensive. Home tanning is an alternative for people with access to fresh hides in good condition. Traditional tanning methods can be messy, smelly, and difficult, but modern products make the process relatively painless.
The quality of the finished product will depend on the quality of the skin you start with. Begin with the freshest sheepskins you can find. Visit local sheep farms at slaughtering time, or find a local butcher with access to skins. If these are not available, purchase pre-salted skins from local dealers or online. Never use a sheepskin that's not fresh or which was not salted immediately. The decay loosens the hair and can make it fall out. Beginners should choose sheepskins with shorter hair, which is easier to tan. Avoid skins which have been stacked after slaughter.
Prepare your sheepskins before tanning. Trim all flesh immediately, and scrape the hide to remove fat and collagen clinging to the inside. If you have very fresh skins, cool them on a flat surface, such as a large rock or concrete, with the flesh side up. Allow the skin to cool in the shade until it is cool to the touch. Salt the skins as soon as they have cooled, using 1.36 to 2.27 kg (3 to 5 lb) of standard table or pickling salt. You must salt skins within a few hours of fleshing to prevent decomposition. Allow the salted skin to sit until most of the moisture has been removed -- a few days to a few weeks.
After salting, sheepskins can be stored for some time. Shake the salt off the skin, roll it neatly, and store it in a climate-controlled location where insects and rodents can't get to it. Pests will chew the edges of a sheepskin if they have access. Avoid areas which may get extremely hot or humid, which can encourage rot even in a salted sheepskin. Long storage -- for several years -- may eventually degrade the skin and cause it to lose hair.
A few hours before tanning, soak the salted skins in clear water until flexible. Apply a commercial tanning solution according to the manufacturer's instructions, or apply a mixture of 546 g (2 cups) of salt and 56.7 g (2 oz) of oxalic acid dissolved in a 3.8 litres (1 gallon) of water to the surface of the skin. No matter which method you use, wear gloves during the process. Moisten the skins with tanning solution for several days. Stack the skins so that the flesh sides are together between applications.
Oxalic acid and several other tanning methods require neutralisation to stop their action. Launder your sheepskins in a solution of water and washing soda -- about 256 g (2 cups) per bath of water. This can require some muscle, since the wool increases in weight when wet. Avoid pulling on the wool, as it can pull free from the skin when wet. Rinse out the soda, then launder the hides normally in detergent and water. Hang or tumble dry on a low setting to prevent shrinkage and hair loss. Dry the skins only until damp.
Stretch the damp sheepskin by tacking it to a wooden stretcher, such as a pallet. Pull the hide as you tack it to create some tension, but don't pull it extremely tight. Allow the hide to dry fully in a shady location. Finish the sheepskin by applying saddle soap and leather conditioner to the flesh side of the pelt. Pick out any remaining bits of straw or other matter by hand, or brush the fleece with a stiff brush. Work any mats apart and groom the wool for display or use in other projects.