For about a year, I've been wearing a Traser watch. I spend a fair amount of time -- ho, ho -- in the dark, up and about, and the phosphorescent dials on my watches, be they wrist or pocket models, glow for about thirty seconds after they are exposed to a bright light, then fade enough so as to be unreadable.
So I did some research into tritium, -- I used to have a tritium nightsight on a handgun that was very nice -- and I found there were watches, designed for the military originally, that use the technology. You can't quite read by the glow, but in pitch black or even partial darkness, you can't miss it. If I were skulking around in the night and trying to stay hidden, I'd wear long-sleeves, or stick this one in my pocket. It is really bright.
Tritium decays slowly, and after ten or twelve years won't glow any more, so I'll have to replace it.
My camera doesn't have the ability to get a good picture of what the watch face looks like in total darkness, but I found this little animated .GIF online that does, and I wanted to see if it would work in a posting. I can do still pictures and now links to vids, so what-the-heck, might as well try animated .GIFs. Great to be living here in the future ...
My mom had a watch like that in the 70's. It was a cheap little thing, but I was fascinated by the glow.
ReplyDeleteI found the history of such things fascinating. Radium dial watches and clocks have been around for nearly hundred years, but they presented health hazards. Slight for the wearer, bad for the people who hand-painted the dials.
ReplyDeleteThey used to sell a radium-dissolved-water tonic for various ailments. And there is a fascinating legal case, a lawsuit against U.S. Radium, concerning the "Radium Girls," in the 1920s. The tiny camel hair brushes they used would quickly mush up, so they were told to use their lips to form a new point. The paint had no taste, but it killed a bunch of women.
Read about it here: http://www.runet.edu/~wkovarik/envhist/radium.html
Phosphoresecent paint, usually non-radioactive, is harmless, but doesn't work very well.
Tritium paint works better, is less radioactive than radium, and decays to helium (being a form of hydrogen).
Tritium gas in itty-bitty glass tubes is best -- it has a half life of twelve years, and the glass face is enough to stop emitted radiation -- supposedly, it won't even penetrate the first layer of human skin.
My watch doesn't kick off a geiger counter.