DuraFil is a surface filler designed to eliminate imperfections such as pits, ding and scratches. This is an easy to use, fast drying formula. Surface area can be built up and sanded to a smooth finish starting with 220 and finishing with 400. Needs to be applied with an airbrush, conventional automotive spray gun, or a high volume low pressure (HVLP) system. Notes: Before DuraFil is applied, firearm should be disassembled and cleaned thoroughly with a high quality degreaser. DuraFil has to be applied with an airbrush, conventional automotive spray gun, or an HVLP system. DuraFil must be mixed with a hardener by a ratio of 12 parts DuraFil to 1 part hardener. DuraFil is a surface filler especially blended for use with any of the DuraCoat topcoat finishes.DuraFil can either air or oven dry.