I stumbled across this article on luminous watches by TC at Kronometric a few days ago and thought I should share here. There’s a lot of misunderstanding and mis-information out there among collectors and consumers about the various luminous materials used in watches and I’d been thinking of writing something myself, but this article gives these articles give a level of detail I don’t think I could match on my own.
It does They do a great job of covering radium, tritium, and promethium radioisotope-based lume systems as well as the luminova compounds more common in modern use.
[EDIT: It’s been brought to my attention that although it adds some new info the article I linked to seems to borrow heavily from another article by Paul Frame of Oak Ridge Associated Universities and hosted by Watch Addicts. See the original Radioluminescent Paint article for the base info.]