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#1
Old 08-14-2006, 12:49 PM
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What Makes Luminous watch hands Glow?

I know they don't use radium anymore (too dangerous). So what substance is used today? My watcg has luminous hands, but the glow is pretty faint-you can make it out at night, but it is by no means very bright. Are non-radioactive materials used?
#2
Old 08-14-2006, 12:57 PM
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Tritium.

Good explanation here . (PDF)
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Old 08-14-2006, 12:58 PM
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There are a few types. Inexpensive watches use phosphorescent materials which "charge" up in bright light then continue to glow for some time in the dark. Others use tritium, a radioactive alpha emitter. These alpha particles are made to excite a fluorescent material which glows; since alpha particles are easily blocked by even a single sheet of paper there is no significant exposure. Another, expensive, option is Luminox. I'm not sure exactly how it works since the page doesn't give out many details--proprietary info, I imagine. They call them "self-powered micro gas lights", whatever that means.
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Old 08-14-2006, 01:03 PM
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Quote:
Originally Posted by Q.E.D.
Inexpensive watches use phosphorescent materials which "charge" up in bright light then continue to glow for some time in the dark.
Such as luminescent, doped Calcium sulfide
#5
Old 08-14-2006, 01:19 PM
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Quote:
Originally Posted by Q.E.D.
Others use tritium, a radioactive alpha emitter. Another, expensive, option is Luminox. I'm not sure exactly how it works since the page doesn't give out many details--proprietary info, I imagine. They call them "self-powered micro gas lights", whatever that means.
Luminox uses tritium (it's a gas, so "self-powered micro gas lights" is marketing)

Luminox is the brightest watch I've seen, bright enough to cast shadows in a dark room, where some of the other tritium watches are just barely visible at night. Could be the OP has a S&W, I wasn't impressed with their glowieness
#6
Old 08-14-2006, 01:31 PM
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Quote:
Originally Posted by Q.E.D.
There are a few types. Inexpensive watches use phosphorescent materials which "charge" up in bright light then continue to glow for some time in the dark. Others use tritium, a radioactive alpha emitter. These alpha particles are made to excite a fluorescent material which glows; since alpha particles are easily blocked by even a single sheet of paper there is no significant exposure. Another, expensive, option is Luminox. I'm not sure exactly how it works since the page doesn't give out many details--proprietary info, I imagine. They call them "self-powered micro gas lights", whatever that means.
So presumably if you wanted to tell phosphorescent from tritium, you could tell it from whether it was a constant glow or a fade proportional to the amount of time since light exposure?
#7
Old 08-14-2006, 01:37 PM
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Originally Posted by Placid Liver
So presumably if you wanted to tell phosphorescent from tritium, you could tell it from whether it was a constant glow or a fade proportional to the amount of time since light exposure?
Or just read the back of the watch.
#8
Old 08-14-2006, 01:46 PM
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Quote:
Originally Posted by Placid Liver
So presumably if you wanted to tell phosphorescent from tritium, you could tell it from whether it was a constant glow or a fade proportional to the amount of time since light exposure?
That is indeed a way as tritium won't fade overnight
Or the dial may have a "T" on it somewhere (bottom of this dial "T swiss made T") or an "H3" (here )
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