Luminous Material Removal

Discussion in 'Watch Repair' started by spiro13, Sep 20, 2015.

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  1. spiro13

    spiro13 Registered User

    Jun 10, 2010
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    Hi

    I have several trench watches that need to have the hands' luminous material replaced. I would like some suggestions on how to safely remove the old radium luminous material.

    Thank you

    Tony
     
  2. novicetimekeeper

    novicetimekeeper Registered User

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    I don't know what would be best as a solvent to remove the old paint, though a degreasing agent is normally part of a paint removal system. However I do have rather more knowledge about the risks with these materials.

    The risk comes from ingesting the material, so no cuts or open wounds, do not breathe in the dust and do not get it in your mouth.

    Double bag any waste produced, gloves, cleaning cloth etc before disposal.
     
  3. RJSoftware

    RJSoftware Registered User

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    One thing I wonder about is if the old radium could be reused. Maybe mix it with some fresh lumen just to see if the radium would activate the fresh phosphorous. I know radium has a long life, but maybe phosphorus does not.

    I wonder what it would do...
     
  4. novicetimekeeper

    novicetimekeeper Registered User

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    The Radium has a half life of 1600 years I think, isn't the material it is mixed with Zinc Sulphide?

    I'm just looking at buying a trench watch and it is an issue. I think I'll simply seal it in a clear box. The problem with the trench watches is the hands are skeletal with the paint filling the gaps not painted on a surface, so it usually just drops out. When you see restored watches they have often had the paint removed altogether but then they look too clean.
     
  5. karlmansson

    karlmansson Registered User

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    Yup, it's usually the flourescent properties of the phosphorous that wear out, the radium will still be highly active. It is mostly beta radiation though and that is efficiently stopped by the skin so not to worry. Do not however under any circumstance inhale it or ingest it! Mixing it with new lume would be a cool experiment, let us know how that goes RJ!.

    By the way, I have a musician/sound tech friend who build a synth based on a Geiger counter. Each tick produces a note. He uses his 1940s, originally lumed watch to play it. Works like a charm apparently!
     
  6. novicetimekeeper

    novicetimekeeper Registered User

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    erm beta isn't stopped by the skin, that's alpha. I think it is the alpha that is responsible for the scintillation. Beta is the source of light from the tritium illumination systems used in modern watches.
     
  7. karlmansson

    karlmansson Registered User

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    Ah. My bad. That should be alpha radiation.
     
  8. R.G.B.

    R.G.B. Registered User

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    I've wondered about replacing the zinc sulphide and a few months ago saw it being sold for that purpose. I've never tried it though. It would be an interesting experiment just to see the difference between luminova and recharged radium. Using the proper precautions, obviously.
     
  9. RJSoftware

    RJSoftware Registered User

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    It would have been pretty cool if you said "works like a chime". Ok, yuk yuk, I know... :)

    Me, I have no plans of tinkering with the radium any time soon. But I suppose it would work.

    RJ

     
  10. RJSoftware

    RJSoftware Registered User

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    Would be pretty neat if it made the stuff glow like crazy...!!!!...!!!

    So bright green you have to turn your eyes away from it, in the dark. I think some of the newer types of phosphorus paint are much brighter than the old formula. Just imagine giving that a radium kick...!

    Might even be problematic, say your going to a movie and your glowing watch hands are so bright people keep telling you to turn off your cell phone.

    RJ
     
  11. karlmansson

    karlmansson Registered User

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    I suppose that's why we have hunter cases! Shouldn't be that hard to design one for a wristwatch.
     
  12. spiro13

    spiro13 Registered User

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    Thanks all for the responses.

    Tony
     
  13. Tyler K

    Tyler K Registered User
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    I found this link to be EXTREMELY helpful and interesting. Please do read (it's a disappointment that you can't replace the Zinc and make your watch glow again).
     
  14. novicetimekeeper

    novicetimekeeper Registered User

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  15. Tyler K

    Tyler K Registered User
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  16. karlmansson

    karlmansson Registered User

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    Well, maybe you can use something other than ZnS to recharge the radium paint? Does anyone know of SuperLuminova can be charged by alpha radiation? It's based on a strontium aluminate compound instead of zinc sulfide.

    https://en.wikipedia.org/wiki/Super-LumiNova
     
  17. MikePilk

    MikePilk Registered User

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  18. novicetimekeeper

    novicetimekeeper Registered User

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    Thanks.

    I agree with all but the last bit about tritium. I have measured the output from tritium lights where the borosilicate is further enclosed in plastic to make a keyring light. There is no doubt that some of the beta is more than capable of getting through both but it is a very low level as the amount of tritium is tiny. I found results were about twice background counts.

    My first trench watch turned up today and I thought it was surprisingly active, it's the gamma that I'm detecting as I have not removed the bezel.
     
  19. Tyler K

    Tyler K Registered User
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    After I read through the article that I posted and thought about it over night...I am starting to question the thing about radium not making Zinc Sulfide glow if they are just mixed together. A couple months ago I bought an old watch lume kit that must have come from the 1930's or 40's. The kit had a vial that said "U.S.approved radium" along with a empty vial labeled " Zinc Sulfide" and a vial labeled " Pigment". If a watchmaker was not able to mix the listed items and not have the mixture glow, why would he or she use up everything except for half a vial of radium? I think that you could mix the radium and zinc sulfide and it might glow. I am going to try it. I bought a lot of 12 Dueber Hampden radium watch faces (some are no good). I will lightly dust the face with Zinc Sulfide and see how it goes. If this does not work, maybe I will scrape some of the radium off and mix it with the Zinc and with a liquid of some sort. Of course when doing this I will be wearing heavy duty gloves, a face mask, cover any cuts and then afterwards wash everything. I am not sure when I will get the Zinc Sulfide but maybe withing a month or two.
     
  20. novicetimekeeper

    novicetimekeeper Registered User

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    You don't need heavy duty gloves, you are more likely to make a mistake if you can't use your fingers. However I'd only do it in a fume cupboard, and tbh I wouldn't be attempting this as my first approach to risk management is always to ask do I need to do this? Could I do something else instead? Only then will I consider mitigating the risk.

    I use thin pvc disposable gloves when checking sources for leaks at work and then dispose of them afterwards. However I'm not expecting to find a leak, if I found one I'd have to take remedial measures and after cleaning would be checking the area with a GM tube for contamination.
     
  21. gmorse

    gmorse Registered User
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    Hi Nick,

    As an alternative to removal, I have in the past applied lacquer to the numerals and hand infills if the owner was happy with this, and the compound wasn't too far gone. Of course, if the hands are corroded at all, the compound has to come out, with appropriate precautions, before re-polishing and bluing.

    Regards,

    Graham
     
  22. novicetimekeeper

    novicetimekeeper Registered User

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    stabilising it seems a good idea, the stuff is more of a risk to the repairer than the owner.

    My new trench watch is going in a display cabinet at school on Monday where it will be quite safe, but I will be investigating the radiation from it at some point. It seems to be very active out of the crystal which suggests the Gamma but very much less so out of the back which suggests not Gamma. I was contributing to a thread somewhere and we were discussing the low power of the gamma emissions of Radium 226, I can't find it now but I'm wondering if the Gamma from radium is not really powerful enough to get through the movement and case.

    I have a radium 226 source at work, I might try seeing what that can get through.
     
  23. Kevin W.

    Kevin W. Registered User
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    I had heard of people putting hands into a ultrasonic cleaner and it removes the material off from them. But what would you do with the solution after.
     
  24. novicetimekeeper

    novicetimekeeper Registered User

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    presumably they pour it down the drain.
     
  25. Kevin W.

    Kevin W. Registered User
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    I sure hope not.
     
  26. psfred

    psfred Registered User

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    Lacquer thinner should remove the lumious material, but then you have the problem of disposal, it's not really safe to mess around with.

    You can replace the lume with modern materials, Bergeon sells a nice kit. You must mix the powdered lume with lacquer in a solution stiff enough to "float" it into the hands and fill the punched out spaces, it's not very hard to do. The modern lumes are rare earth spiked zinc sulfide, and will glow for at least 12 hours after a few minutes exposure to UV -- brighter than the radium dial to start with, but fade rather than staying lit but dim.

    Dead lume has the zinc sulfide failing to glow, it's still "hot" if it's radium. Tritium stop glowing because it's gone, half life is something like 18 months.

    The worst problem with radium dial watches is not the radium, it's the fact that the decay product of radium is radon gas, which in turn quickly decays into other elements in the lanthanide series (if I remember my atomic chemistry, which is fairly iffy by now). This means that the entire watch is contaminated with radioactive heavy metals, some of which emit much stronger beta particles than tritium. I have a number of them I'm letting sit until I decide how to handle them.

    Radium was used up the the mid 50's -- the dial will be marked most of the time with a -RA rather than the -T of tritium dials. Naturally, something like a trench watch will NOT be marked, but you can assume any watch before 1950 with luminous dial or hands contains radium.

    One watch won't hurt you, but if you do something silly like collect the hands and dials in a container, it can become radioactive enough to cause trouble, emitting not just alpha or beta particles, but gamma as well.

    There have been some discussions about this here and on other forums. I suspect some institution (hospital, University, etc) that uses radioactive materials and has a disposal system would help you out with small amounts of radioactive waste -- cleaning solvents, the rodico you use to clean the dial, rinse solutions, etc. I strongly recommend you flush the movement of any radium dial watch into a sealable container BEFORE you disassmble it, to at least rinse off any radioactive metal dust that is not merged into the plates and parts.

    I've never heard of an old watchmaker dying of radiation poisoning, but it's pretty easy to take some simple precautions.
     
  27. novicetimekeeper

    novicetimekeeper Registered User

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    I don't know about the rules in the US, apart from knowing that you don't need a licence to collect the watches, but I'd be very surprised if anybody was prepared to help you as here it would mean taking full responsibility for a source not on your licence. Disposal for somebody with a licence is frighteningly expensive.

    I also think that whilst wetting the material is potentially safer for the person handling the watch so as to reduce the chance of airborne particles the problem with this is that it multiplies the disposal issue as you now have a lot of contaminated liquid to work with and contaminated equipment if you used a bath.

    Radon is a decay product of Radium 226 but I'm not sure that is really the biggest problem, though it is the reason given for closing vintage aircraft cockpits to the public. I check our sources at school for leaks and our radium 226 is kept in a lead pot in a box, I have to check the pot for contamination and clean it, I just have to use disposable gloves, lab coat and safety glasses, I'm not required to wear full body armour.

    Hear in the UK we have houses that are fitted with forced ventilation to reduce radon build up from the natural riock, I know parts of the US have the same problems, I don't think the odd watch is going to cause a problem like that but hundreds of them will.

    The big problem with the paint used is that it is unstable after all this time, causing it to flake or powder. Ingest that radium and the body sees it as calcium so not only have you ingested a poweful alpha emitter but around 30% of it will not pass through your body but be laid down in your bones to be with you permanently which seriously increases the risk of bone cancer.

    The ladies that were employed to paint these dials had no further health issues after they stopped licking the brushes and proper precautions were employed, you just need to keep the stuff out of your body, not just your mouth but also eyes or any other entry point like cuts on the skin or inside the nose. That's why it is the flaking paint and airborne dust that is the issue.

    Tritium is a much safer solution for the watch industry but has a half life of around 12 years. That means that it will gradually decrease in brightness for twelve years until it is half as bright, then over the following twelve years to half as bright again and so on. That's not a problem for a cheap watch but you can see why Rolex have not gone down that route, they don't sell watches with built in obselescence.

    I'm getting a much more sensitive detector at work in the next week and I'll have a bit of a play with one of the two trench watches I have to see how they are behaving, as well as checking the case to see what has migrated to the movement.
     
  28. karlmansson

    karlmansson Registered User

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    You sure about that? What brand? Apparently Super Luminova at least is based on a strontium aluminate compound instead of zinc sulfide.
     
  29. novicetimekeeper

    novicetimekeeper Registered User

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    I think you are right, doped strontium aluminate is used for more expensive phosproescent coatings as it lasts longer, I think up to 12 hours rather than over 12 hours. Copper activated zinc sulphate is the cheaper end of the market and won't last as long.

    Unlike the radioluminescence of the radium paint the activation is not built into the paint so a light source is required to activate the coating which then emits light over an extended period as the electrons return to their original energy levels.
     
  30. RJSoftware

    RJSoftware Registered User

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    How does the gas/tritium capsules work..?
    Is there tritium gas contained somewhere?

    RJ
     
  31. novicetimekeeper

    novicetimekeeper Registered User

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    The tritium is contained in a borosilicate capillary tube that is coated internally with phosphor. The tube is sealed by a laser melting the end of the glass.

    You get different colours according to the phosphor used but to our eyes the greens/blues/yellows are the brightest. The tritium emits beta particles which cause the phospor excitement, when the electrons in the phosphor atoms return to their original level they emit a photon.

    The beta emission is at a low energy level so very little escapes the borosilicate and usually the glass capillary is encapsulated in something else.
     
  32. Pvt-Public

    Pvt-Public Registered User

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    I would really like to know how Tritium (a gas) was used to make a liquid paint such as used on this. There are little dots at the end of the hour markers and fill in the hands. There does not seem to be any "tubes". Any ideas? I'd really love to get this one glowing again, but don't like the way luminova and such "dim out".
    P1221810.jpg
     
  33. novicetimekeeper

    novicetimekeeper Registered User

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    Tritium is used to make dots, they are just glass capsules again, but I don't think that watch is tritium is it? What makes you say it is?

    As you say, Tritium is a gas , it is an isotope of Hydrogen, it doesn't have any form of luminescence itself but is the ionising source used to excite phosphor coatings on the inside of whatever contains it.
     
  34. Pvt-Public

    Pvt-Public Registered User

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    It is a late 60's Omega Seamaster, at the bottom of the dial it is labeled -T SWISS MADE T- which I have been told the 2 T's mean it has Tritium on the dial and hands. And this was made while Omega was using tritium for luminous material. As you can see by the following pictures these are not "tubes" or "capsules" they are dots of some kind of paint. It may not be real clear in the pics but it is in person.
    P2212106.jpg IMG_0374.jpg
     
  35. novicetimekeeper

    novicetimekeeper Registered User

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    #35 novicetimekeeper, Oct 2, 2015
    Last edited: Oct 2, 2015
    I went away and thought about this and then tried to find out more about this watch. I had not heard of tritium paint before but thinking about it I don't see that it isn't a possibility. I wouldn't expect iot to be as good as the borosilicate capillary system though.

    Tritium the element is a gas, it is an isotope of Hydrogen. However like the hydrogen we are more familiar with it can be found in compounds. If they make a compound with tritium rather than hydrogen it could then be a constituent of the paint and the tritium will still decay in the same way emitting beta. If that compound is part of a paint containing a phosphor compound then you will have radioluminescence, though I don't think it will be as bright.

    The beta will be emitted by the tritium but it won't necessarily impact with phosphor compounds on the surface of the paint so not all of what it produced will be seen.

    Contrast this with the glass tubes where you have a thin layer of a phosphor compound surrounding pure tritium gas, so every photon released can contribute to the brightness of the lume.



    In both cases you still have the half life of 12 years to contend with but you can make a more useful lume by putting more tritium in the tube so that it starts off brighter and 12 years later half as bright is still a good brightness.

    You can't do that with the paint system.

    I can't find anythjing about how tritium paint was made so I don't know what the compounds would be but this is the way it would work

    (Ah, we cross posted, but my explanation holds, it seems to fit with your watch)
     
  36. RJSoftware

    RJSoftware Registered User

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    The best watch ever for solving the problem of glow is the Indiglo.

    I sometimes wish I could convert one of my favorite mechanicals to have something like an Indiglo.

    Somebody should come up with a kit to convert a watch. Some kind of attachment for battery and swich, but probably would require a small hole on or near crystal for conductors and waterproof plug.

    Probably too the dial could remain original with transparent fluorescent sticker. I don't exactly remember how it works but I think the fluorescent part is activated by stepped up voltage created from transistor. Thin sheet like a capacitor... can't remember.

    That would make a fun project.


    But re-using radium. I don't know. I'd hate for anyone to get sick from an accident.
     
  37. novicetimekeeper

    novicetimekeeper Registered User

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  38. psfred

    psfred Registered User

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    There have been several mechanisms for using tritium in luminous materials. Some use tritium gas in tiny glass tubes coated with phosphor, and others use tritium replacing hydrogen in other compounds. The microtubules or other silica encapsulated systems work the best, but since tritium has a short half life the dials go dim in a few years due to lack of radioactivity from the tritium, as it is gone.

    A watch from the 70's with a tritiated dial is now only showing "glow" from the luminescence of the zinc sulfide, which only last an hour or so after exposure to UV. If this is not a problem for you, I'd not even bother to replace. If you want much brighter and longer lasting glow, replace with modern materials. You will NOT be able to obtain tritiated paint unless you are a military contractor. And they tend to use radium based paint anyway, it lasts longer in use.

    Disposing of tritiated paint is not an issue, as the tritium is gone in a decade or so. Radium lasts forever in human terms, but tritium "goes away".

    Modern rare earth spiked luminescent materials are much brighter and do not contain radioactive materials, but will only glow for 12 hours or so when new, and gradually become less bright and of shorter duration of glow as they age. I'm happy to make the tradeoff, myself.

    Peter
     
  39. RL

    RL Registered User
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    The "T" beside the word Swiss at the bottom of the dial does indeed mean Swiss
     
  40. psfred

    psfred Registered User

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    Sorry if I mis-typed that, but the T means the luminescent material on the dial contains tritium in some form, it's also present on Seikos, which are NOT made in Switzerland. Radium dials after 1950 or so, as far as I can determine, are marked with an RA. I believe some military issue watches had radium dials after radium was removed from civilian production, as well as on clock faces and other dials in military equipment, so one should be careful and check before disassembling.

    Seikos are usually marked for caliber and case, while Swiss made watches are usually marked "Swiss".

    Peter
     
  41. novicetimekeeper

    novicetimekeeper Registered User

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    Tritium never goes away as such, a half life is just that, a half life. After 12.5 years the activity will have dropped by half, after 25 years it drops by another half, so a dial from 1970 will now be at 1/16th of the activity. It won't be glowing much but it would still be sensible to be cautious with it.
     
  42. karlmansson

    karlmansson Registered User

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    Well yes, in a manner of speaking. But then again parts of the tritium will decay into other isotopes. So after 12.5 years, half the tritium will have decayed into something else. ALL of it will never go away but most of it will.
     
  43. RL

    RL Registered User
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    Stop the presses---lol.
    I was in a hurry and did not proof read my post above.
    It of course was supposed to read the " T " beside the word Swiss does indeed mean Tritium.
    Sorry if I added to anyone's confusion.
     

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