UV Clay When UV clay is exposed to ultraviolet light, the milky white color gradually turns pink. Also, after a certain amount of time, it gradually returns to its original color and fades. Why not try drawing secret messages with a UV penlight? Please do not use on carpets or in dusty places. There is a dent in the lid from the time of purchase. Brand new, unopened. Please prepare your own penlight. Stored at home. I have a cat. Please refrain from purchasing if you are concerned. Instant purchase OK. Tools...Resin/UV light