Using these Polytek PolyColor dyes is easy. First, pick the color you like from the available options - black, brown, blue, green, red, yellow, white, or fleshtone. When you're ready to color your liquid polyurethane rubber or plastic, measure the amount of dye carefully. For most dyes, add up to 0.5% of the total mixed weight of the rubber or plastic. But for PolyColor White and PolyColor Fleshtone, you can add up to 2% to polyurethane rubbers and resins. Before adding the dye, make sure to stir PolyColor White and PolyColor Fleshtone well. This will help the color blend evenly. Store the dyes in a cool, dry place to keep them in good condition. If you have any leftover dye, seal the container tightly to prevent it from drying out.