Fluorescence, Maybe O/T Here...
 

Just noticed that all 436 of my 1962 Topps fluoresce under my blacklight flashlight. Pretty interesting to see. So, too, all my other post-war Topps and Bowman cards that I have tested. The only 1940s post-war card I have is a 1949 Satchell (sp) Paige (relax, it has a thumbtack hole), and I can't get to it just now. But, all my 1941, 40, 39 Play Balls and 1933, 34 Goudeys and on back tobacco and candy cards do not. I have read that ink changed in the 1940s. Must have been after WW2. What was the reason that ink changed? Anyone have an interesting fluorescence story?

Often not the ink but the brighteners that are used on the paper.

Optical brighteners began to be added to paper to make it brighter, whiter, after World War II. I don't think it's the ink on your 1962 Topps that is fluorescing, it is the paper itself.

I'm glad to hear that you're shining your black light on cards. I wish more folks would use those.

First time I was glad I used one was with a Remar card for a Pacific Coast League set, from 1946 or 1947, I think. I got it in an eBay auction. It blasted bright blue when the light hit it, the dozen or so other Remar cards I had didn't fluoresce at all. I messaged the seller, told him that it fluoresced and it shouldn't, it was not genuine. I asked him to refund my payment and double shipping fees so I could be refunded those and could also send it back. He refunded payment and shipping and said to not bother sending it back. From the words he chose I inferred that he knew it was copied or printed on cardstock and not genuine.