SO-Strong® liquid urethane colorants can be added to any Smooth-On liquid urethane rubber, urethane plastic or urethane foam (do not use with Smooth-On silicones). They can be used to create a variety of color effects for a wide range of material applications. For glowing fluorescent color effects, use Ignite colorants. The NEW SO-Strong® 9 pack gives you the opportunity to experience each color without spending a lot of money. SO-Strong® colorants are highly concentrated, offer excellent dispersion and consistent color. A very small amount will color a proportionally large amount of liquid urethane material. The more you add in proportion to the volume of liquid urethane, the more dramatic the color effect. Recommended loading range is .01% to 3% of total system weight. Do not overload the liquid urethane system or cure inhibition / oozing may occur. If this is your first time adding color to a urethane system, it is recommended that you test the color effect by adding a few drops to a small amount of material and observe the outcome.