My Indian friends would never even think of any other way of scraping and preparing a hide. After cutting off the hair as in the wet scrape method, the basic process is to get the skin good and wet, stretch real tight and put it outside at a temperature of -20 degrees Celsius or colder. Then a scraper (usually an ax head to which is attached a long perpendicular handle) is used to pull off scrapes of skin which look a little bit like very thin wood shavings coming off with a hand plane or spoke shave. This process is repeated until the skin is of uniform thickness everywhere. The rest of the process resembles the wet scrape method.
Dry-scrape typically uses a sharp blade to de-hair the hide while it is stretched tight in a rack. The hide is usually stretched soft in the rack also.
Thomas J. Elpel
Hollowtop Outdoor Primitive School, Box 691, Pony, MT 59747-0691