MAS Fairing Compound is a lightweight, two-component epoxy putty that can be used for fairing, filling, shaping, and repair. It has a convenient 1-to-1 mix ratio by volume and undergoes a color change to ensure it is properly mixed. It has excellent sag resistance for application on vertical or inclined surfaces and is easy to sand when cured. At 70°F, MAS Fairing Compound becomes sandable in just 6 hours. It also resists moisture and can be used above or below the waterline on a variety of substrates, including fiber-reinforced plastics (FRP), aluminum, steel, and wood. Excellent sag resistance on vertical surfaces Can be used above or below the waterline | MAS Epoxies Fairing Compound Kit, 2 Pints in Sand