Remove all of the fat, tissue and flesh from the buck (or doe) skin. Lay the hide on a flat surface like a table and scrape it with a sharp, long-bladed knife. Every bit of fat, tissue and flesh must be removed in order for the hide to tan properly.
Pour 1 lb. of alum into a plastic bucket, Add one gallon of warm water slowly, a little at a time, until the alum is completely dissolved.
Dissolve 2 1/2 pounds of salt in 4 gallons of water in the plastic garbage can. Pour the alum solution into the garbage can and mix well.
Immerse the skin in the combined solutions. Let it soak for a week, stirring twice a day to make sure that every part of the hide gets exposed to the mixture.
Remove the skin from the soaking mixture and let it drain thoroughly. Rinse it with running water for at least 15 minutes.
Tack the wet deer hide to the sheet of plywood with the skin side facing out. Allow the skin to dry partially, keeping it out of the sun.
Rub the skin with a light coat of warm neatsfoot oil when it is almost (but not quite) dry. Remove any excess oil with an absorbent cloth or small towel.
Dampen the flesh side of the hide with a moist cloth, but don't let it get too wet. Rub the flesh side over a chair back until it is soft and supple, applying a tiny bit more neatsfoot oil as necessary.
Rub the skin side all over with fine grit sandpaper. When the skin is smooth, your hide is ready to be used as a rug.