# Before there was lume



## JDMdenon (May 11, 2017)

Hi All,

Was having a look at some old pieces an was curious about whst they used before superluminova and all that jass came out! Am I right in saying thy used radioactive materials??

I think my omega geneve has some sort if material applied to the hands but it doesnt work anymore.

ta!


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## scottswatches (Sep 22, 2009)

yes. Up to 1955ish they used Radium, which has a half life of 1,600 years. Then they switch to Tritium, which has a 25 year half life


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## animalone (Apr 11, 2017)

Still very nearly as radioactive as the day it was made.


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## scottswatches (Sep 22, 2009)

these 1953 military issued Omega's had the radium removed, and Tritium used instead (hence the T under Omega). Apparently they would set off the giegercounters with the radium!

Tritium is still allowed to be used on divers watches. Its radioactive properties mean it does still glow, whereas Superluminova needs to be charged from a light source so is no good if working for prolonged periods underwater


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## JDMdenon (May 11, 2017)

scottswatches said:


> yes. Up to 1955ish they used Radium, which has a half life of 1,600 years. Then they switch to Tritium, which has a 25 year half life


 When did they stop using tritium Scott? Also, do people ever get the tritium re applied? I'm a great believer in it's only original once so I wouldn't be bothered but just out of interest?

Also, how do people go about servicing if the the face contains radium? What safety measures are put in place??



scottswatches said:


> these 1953 military issued Omega's had the radium removed, and Tritium used instead (hence the T under Omega). Apparently they would set off the giegercounters with the radium!
> 
> Tritium is still allowed to be used on divers watches. Its radioactive properties mean it does still glow, whereas Superluminova needs to be charged from a light source so is no good if working for prolonged periods underwater


 Is this similar to "t Swiss t"??


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## scottswatches (Sep 22, 2009)

JDMdenon said:


> When did they stop using tritium Scott? Also, do people ever get the tritium re applied? I'm a great believer in it's only original once so I wouldn't be bothered but just out of interest?
> 
> Also, how do people go about servicing if the the face contains radium? What safety measures are put in place??
> 
> Is this similar to "t Swiss t"??


 Some watchmakers won't touch radium watches. I don't think you can get Tritium reapplied either, but you are right with the T Swiss T. It was mid nineties before most companies stopped using it

https://gearpatrol.com/2017/02/13/how-watch-lume-works/


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## Padders (Oct 21, 2008)

It was actually a bit later that some manufacturers, Omega included, moved over to Tritium. Many Omega models (inc Speedmasters, Seamasters) were still using Radium lume until about 1962

Radium lume turns an attractive orange shade (as seen above) whereas tritium tends to go more yellow. They actually fail in opposite ways. Radium is so radioactive that it literally burns out the phosphor component meaning most Radium lume no longer reacts to UV light but the material is still measurably radioactive whereas with tritium based compounds, usually there is some residual short lived luminescence after UV excitement but the 13 year half life of the tritium means there is very little radioactive excitement left. Tritium is a beta emitter so less physiologically harmful than the alpha emitted by radium anyhow, beta is just high energy electrons like you would find in a CRT tube.

Luminova works via a different process involving electrons jumping about within energy states so emits no harmful radiation at all and should in theory never degrade or deteriorate.



JDMdenon said:


> When did they stop using tritium Scott? Also, do people ever get the tritium re applied? I'm a great believer in it's only original once so I wouldn't be bothered but just out of interest?
> 
> Also, how do people go about servicing if the the face contains radium? What safety measures are put in place??


 Radium is an alpha emitter which means it will do very little harm through skin (the big heavy He nuclei are high in energy but short in penetration) but is incredibly bad news if inhaled and allowed to act from within lungs. A face mask would be a minimum I should think.


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## animalone (Apr 11, 2017)

Old radium lit with UV, it stops glowing very quickly when the UV source is removed.


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## JDMdenon (May 11, 2017)

Thanks very much for the detailed replies @Padders and @scottswatches. I remember being taught the various types of radioactive material types alpha, beta and gamma.

Gamma being the most harmful!

Our teacher once told us about how a spy who was assassinated by digesting an alpha material in his sushi!!!


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## Karrusel (Aug 13, 2016)

I started a thread on Promethium147 (Pm) watch lume a while back, may be of interest to you...



Karrusel said:


> At the base of the dial on the Rotary Sport watch is the letters 'Pm'.
> 
> As I had not seen this before (honestly) I proceeded to do a bit of research.
> 
> ...


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## vinn (Jun 14, 2015)

> yes


 the thing about radium is "the original painting it on instrument dials" - killed many "defence workers" licking the paint brush. scrapeing it off 50 year dials is not a big thing; if you have a Giger Muller counter. vin


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## Always"watching" (Sep 21, 2013)

I must admit that having examined the whole question of lume and safety in great detail due to my own concerns about it, I have come to the conclusion that I personally would avoid buying old watches that have been liberally lumed with radium-based lume. For me personally, it may be true that just wearing a radium watch so lumed is probably adding only a negligible amount of radiation in the scheme of things, but the thought of having a personal source of penetrating gamma radiation on my wrist day after day is just one step too far. Radium is a source of all three major forms of naturally emitted ionising radiation - alpha, beta, and gamma. The radium in lume has a very long half-life, and the amount of radiation being emitted in even a very old radium-lumed watch will be almost the same as when the watch was made, although the degradation of the phosphor caused by being burned out by the radiation may mean that there is no glow left.

When it comes to tritium-based lumed watches, I would wear one but not every day or for extended periods. These watches are far safer than those lit by radium lume, partly because the beta radiation - the main emission from tritium - emitted can barely pass through either the watch back or even the crystal, and partly because the short half-life of tritium (just over 12 years) means that an older tritium-lumed watch will have lost a significant amount of its radiation, unless it has been re-lumed at some stage. There is a misconception about tritium-lume concerning the nature of its use - tritium is an isotope of the gas element, hydrogen, and tritium tube technology takes advantage of that fact to enclose tritium in tiny glass tubes that have a phosphor applied to the inner surfaces. This form of lume is effective until the half-life of the gas starts to reduce the luminosity. It is sometimes stated that tritium lume always requires to be used in gas form, but in fact, many watches have a tritium/phosphor mix actually painted or applied to the watch dial in the manner of radium lume.

My most important piece of advice concerning any watch that contains a lume activated by a radioactive substance or a lume of unknown composition is that (unless properly equipped to carry out such work), the collector should avoid opening the watch, most especially when that reveals the dial to the elements, and never tamper with the lume itself. It may seem over-zealous, but removing old lume and cleaning old dials when the watch has been lumed using a radioactive phosphor is, in my opinion, a professional business.


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## Padders (Oct 21, 2008)

Having studied and worked with radioactive sources, some rather nasty I personally think that while Radium needs to be treated with respect and appropriate precautions taken when opening a watch, Tritium lume actually offers virtually zero additional risk to life over normal everyday activity. Even a radium dial won't dose the wearer significantly or meaningfully through the movement and caseback which is an effective shield, as I noted earlier it is mainly a Alpha emitter which is a very short range ionising radiation rather than gamma which is highly penetrating. Radium has a long and complex decay chain but gamma doesn't feature significantly in this so isn't IMO a real cause of concern unless you lick your dials on a regular basis. If you lived in Cornwall, spending any length of time in your house cellar would probably be as harmful as wearing a Radium lume watch as alpha emitters are really only deadly when ingested or inhaled.


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