I don't know about protective patina, but he does "secrete" quite a bit.(If you don't believe me come check out the children's workshop at the next conference. He will be leading.) Maybe that is the answer.
I was cleaning mine every day until I got curious about the way his chisel is reacting. Now I am letting mine stay dirty for a little while to see if the accumulative affect of the oak changes the look of my chisel. Mine is practically brand new(6 months old) and his is several years used. Perhaps I will get to the bottom of this and maybe not. Thanks though,
bloveland
