I found this very good summary in a Yahoo forum. (You can visit Valmour as well)
The egg white until stiff foam which is spread with a clean pad is an excellent cleaning agent for clothes in plain leather. We finish the operation by shining leather with a woolen cloth. The dark leather is maintained by moving over a flannel cloth sprinkled with talc and then impregnating it with a paste made of 2/3 turpentine 1/3 soft wax bee. The leather is allowed to soak up the dough and then shine with a cloth.
I own a cowhide hat The SwagMan, and I noticed sweat stains at the front of it .
I fixed up the trouble with the 'terre de Sommières' powder.
I covered the stained parts with this powder, then left overnight.
The next day I sucked up the powder and brushed the hat with a suede brush. Very effective.
I finished by applying a waterproof spray.
Get to this site and watch some videos about many different hats: Connerhats.
Renovate a wet leather cloth
Your leather jacket was wet from rain? Put it flat on a towel. Dry it with a clean white duster, gently dabbing. Then go over another duster (just as white and clean) moistened with glycerine. And finally, do shine with a woolen cloth.
Renovate a dried leather cloth
Your garment leather look bad? Spread a paste : 2/3 turpentine - 1/3 of soft wax bee. Allow the product to dry, then do shine with a woolen cloth.
Repair cracked leather
You must fit under the cut a piece of leather, then stick the two sides with glue for leather. Allowed 15 minutes for drying. Plaster down the 2 lips flat. It strongly urges being careful because the glue for leather is a contact adhesive, and there will be no possible repositioning.
Detach Leather cloth
Move over a duster soaked in a mixture of water and alcohol (9/10 water-1/10 alcohol).
Sponge up the drink with paper towels and then pass on the stain a duster soaked in a mixture of 50% water 50% alcohol.
The burn marks on the leather are difficult to remove. But if superficial, you can always try to mitigate by gently passing over first pumice, then dab with a duster soaked in oil. Then wac the leather with the same color.
These spots are eliminated by letting them dry and then moving vigorously over a soft brush. Wax then luster.
Gently scratch with a wooden spatula. If some candle remains, put a layer of paper towels and pass over a hot iron, then sprinkled with Sommières soil. Overnight is expected. Brush next morning.
Water stains are removed with a cotton dampened with cold water and mild soap, pass on the leather another damp cotton to rinse. Dry and wax with a colorless polish. Vaseline also removes stains caused by water. Allow to penetrate before polishing.
Mildew stains are removed by blotting with a cloth soaked in glycerine. You can also rub the spots with a little turpentine.
Do not attempt to remove grease stains with water and soap. It is better to sprinkle talcum powder or Sommières soil. Wait several hours then brush. Repeat if necessary. If the task is old, it should be warm with a hair dryer before you sprinkle talcum or Sommières soil. You can also remove these stains by applying a paste made of rubbing alcohol and crushed chalk. When the paste is dry, gently brush it.
These spots can be removed by dusting with talc or Sommières soil. Several hours then brush are needed. If stains resist, dab with a cloth soaked in ammonia diluted in water, then sprinkle talcum or Sommières soil.
Sponge coffee, then pass a duster soaked in a mixture of 50% water - 50% alcohol.
After gently scraping the stain with a wooden spatula or a spoon, dab the stained area with a duster dipped in turpentine.
A spot of grease on the leather is removed by covering it with Vaseline. Let acting. Go over with a duster. If a grease stain remains, sprinkle with talcum powder. Wait, then go over with a new duster.
A soft brush dipped in warm water we go. Wipe. Use colorless wax.
Dab the stains with a cloth soaked in warm milk or unboiled 90° alcohol. Wax. If the stain remains, use hair spray. Ink is wiped with a clean duster as soon as it becomes diluted. Repeat until stain is off.
Remove those spots by moving over a cloth soaked in 28% ammonia water.
These stains are removed by blotting with a duster soaked in soapy water.
Remove with turpentine.
Remove with vinegar or acetic acid diluted in water.
Sponge maximum tea, then pass on the stain a duster soaked in a mixture of 50% water - 50% alcohol.
Dab with a damp duster.
Clean with a spray of "Pliz" type. With a simple spray product, once or twice a month, the leather restored to its original luster. You can try beewax paste as well. This wax contains turpentine, which 'll feed the leather. Then just wipe over everyday.
It is advisable to clean the clothes in water with Marseille soap and then to go over a duster soaked in lotion or cleaning milk.
The first thing to do before you wear a lambskin cloth is to protect it with a waterproofing spray of TexGuard kind. After that, if you act fast enough, you can easily remove them with a small white eraser or a clean small brush.
Clean with a sponge soaked in the foam of a mild detergent in warm emulsified water. In order to avoid wetting the garment, using only the foam, without the liquid. Once finished, dry using a towel. It is not advisable to give a lambskin cloth to the cleaners. Degreasing chemicals make it harder, clearer and much less beautiful.