Studio Pro 7/32" Black Backed Foil is a 1.0 mil copper foil and is sold in 36 yard roll in a unique “Easy Pull” plastic dispenser makes for trouble-free application and kink-free storage. When To Use: Black backed copper foil has an reverse black coating to help camouflage the appearance of the foil when used on clear, wispy, non-opalescent glass and mirror and applying a black patina.