The Ignite line of liquid fluorescent colorants is compatible with Smooth-On^® urethane rubbers, urethane plastics, and urethane foams. The fluorescent or “glow” effect is maximized under ultra-violet light or “black light.” The most dramatic color effect is realized when an Ignite colorant is used with a clear or translucent urethane rubber (such as Clear Flex™ 50) or plastic (such as Smooth-Cast™ 325).