Jared,
When we set-up the systems for Rawlings at most of the major league ball parks to engrave the bats we would use turtle wax to coat the bat at the engraving area and then laser, then wipe in the paint fill. I can not give you any details on the paint they used because they kept it secret. It was just in a Tupperware bowl and they took a rag and wiped in into the engraving let it dry for about 20 minutes and then wiped it off. They would do about 100 bats during a normal nine inning game and they had three different colors that they used gold, silver, and black. I believe that the paint was a water based paint that dried fast but when I asked what it was they would not tell me.
the turtle wax helps with keeping the paint off of the UN engraved areas and cleans off very easily.
Wish I could get you more info on the paint but I know it can't be anything special.