While I can't tell you an exact formula to use, I would suggest trying to use an air hose blowing on the bit to keep it cool. Doing this by hand (holding it) is usually ineffective and tedious. Rig up something that can blow on the bit unattended.
I don't know your application, but Komatex comes in a few different shades of grey as well as pastel and primary/solid colors & it cuts like butter.
-Brady
