flake off of (something)
1. To fall from something in small bits or pieces. Ugh, look at all the glitter that's flaked off of my birthday cards.
2. To cause something to fall from something else in small bits or pieces. Hey, stop touching the wall—you're flaking the paint off of it!
flake something off of something
and flake something offto make bits or flakes break off from the whole. The sculptor flaked bits of stone off the block, but you could not yet see what the block was going to become. She flaked off a little more.