A 10 mil paper backer, as the name suggests, refers to a backing material that has a thickness of 10 mils or approximately 0.01 inches or 0.254 millimeters. This paper backing is often used in conjunction with veneers to provide support and stability during installation or to add an extra layer of protection to the wood surface underneath. The paper backer can also help improve the integrity and reinforce the bond between the veneer and the substrate it's being applied to.