What Makes Luminous watch hands Glow?

[ralph124c]

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?

[Clothahump]

Tritium.

Good explanation here . (PDF)

[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.

[Squink]

@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

[Bobotheoptimist]

@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

[Placid_Liver]

@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?

[Bear_Nenno]

@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.

[Bobotheoptimist]

@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 )