The glow-in-the-dark pigments contain phosphors. They absorb UV light photons and hang on to them, slowly emitting new photons with much lower energy giving a soft glow you can see in the dark. This set includes four 10ml pots of glow-in-the-dark paint. Clean up with soap and water. Store with lid tightly secured in a cool, dry place. Use Magic Black Light for full effect. Recommended for ages 5 and up.