devil float meaning

[Engineering]
"A hand float containing nails projecting at each corner and used to roughen the surface of plaster to provide a key for the next coat. Also known as devil, nail coat."

Examples

1. They're joking around like old pals when the devil floats a wager : He believes humankind was God's biggest mistake, and if he can prove it, he gets to move back to heaven and run his operation from its more pleasant accommodations . ( Through the throne room's vast windows, we see that heaven is a vast, green golf course .)