Had the same idea 5 years ago but never tested it. The way I thought about solving it was more complicated, it involved a laser protector matching the absorption frequencies for each photochromic crystal (CMY) thus selectively heating each color. The only manufacturer of photochromic inks I knew was Zink but I didn't even imagine they would be willing to ship me some samples because they use them for their products. I could have asked my university for help but their policy was to keep 98% of the patent.
[+] [-] 2_listerine_pls|6 years ago|reply
[+] [-] xet7|6 years ago|reply