Dry Film Thickness (DFT) is the thickness of a coating when dry, expressed in mils. One mil is equal to one thousandth of an inch. 1 mil = .001 inch (1/1000). For comparison purposes, the thickness of one sheet of standard paper is approximately 3-4 mils in thickness. Rust Bullet should be applied in thin, even coats. Each coat should be approximately 3-4 mils or one sheet of paper, and at max no more than 6 mils to prevent any coating failure.