I recently came across a short film from 2012 called "Blood and Leather: The making of a Maasai shield". Although it is technically rawhide and not leather, I was hoping someone could help me out. It appears to be a pretty straight forward process. They stretch the hide, staking it to the ground flesh side up and scrape it. At about 1:50 into the video they cover it with a power substance. That is the part I could use help with. any ideas what the powder is. At first I thought salt, but in my opinion it looks too fine to be salt. Then I thought maybe it was some kind of wood ash. What do you folks think?