Photochromic: Light-Activated Screen Printing
Photochromic coatings change from clear to color when exposed. Specifically, they change color in response to ultraviolet (UV) light, usually from the sun or a black light.
Photochromic behavior can be either reversible or irreversible. Reversible photochromics transform from clear to color by changing their chemical structure after absorbing UV light. The UV light causes the photochromic ink to absorb color (like a dye), and then change back to clear when the UV source is removed. They can cycle thousands of times depending upon the application. They can also change from one color to a different color by combination with a permanent pigment.
Photochromic Example Video