PHOTOCHROMIC INK

An ink containing photochromic pigments which change their color when exposed to UV light. After the UV light source is removed, the image printed in photochromic ink stays visible for some time and then becomes pale and disappears. This process can be repeated an endless number of times.

a —  Paper substrate; b —  Image printed in photochromic ink. UV light; 

c —  Zoomed fragment. View in white light, 10 seconds after the UV light source is removed

a —  Paper substrate; b —  Image printed in photochromic ink. UV light; 

c —  View in white light, 10 seconds after the UV light source is removed