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How to identify a relume by UV light inspection?

  1. nitediver Jan 3, 2021

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    We are all aware that one of the most important questions on a vintage watches is whether the dial is original or not.

    I am aware that there are many factors to consider when inspecting vintage dials, and reaction to UV light is only one of them. Still, in the following I will focus on reaction of tritium dials to UV light. I have only few watches with radium dials, set lets set them aside for this post.

    I have been doing some reading on this topics on various forums, but i still struggle to make real sense out of it so I am looking for your opinion and advice.

    I studied some of my own watches and dials for comparison. I have some 30 plus vintage watches and almost all my vintage watches of various brands and periods glow when activated with UV light, and after a few seconds the glow fades. Some watches do not really glow, but rather reflect, similar to a reflective tape you will find on clothing or a bicycle helmet.

    However, some dials do neither glow nor reflect the light, and this is what puzzles me.


    To research the topic, i inspected some of my own watches and spare dials which do not show the typical glow under UV light. I looked at the following examples:


    1) Rolex GMT Master 16700 from 1989

    2) Rolex GMT Master spare tritium dial

    3) Rolex 16570 black spare dial

    4) Rolex 16570 white dial spare dial

    5) Zodiac Sea Wolf

    6) Glycine Airman SST 1970’s

    7) Freese Series 1 – as comparison of what can be done with modern reluming.


    I sourced the spare dial No. 2, 3 and 4 from a reputable seller in good standing on VRF, so I have every reason to believe they are legit. I purchased them with the intention to fit it to a 1990s Explorer II Ref. 16570 , as many of those have service dial. But for various reasons, I haven’t pulled the trigger on a Explorer II, so as of now I only have the dials.

    I focus on the lume dots / triangles rather than on the hands in my comparison. Here are my observations: (pictures are in sequence)

    1) Rolex GMT Master 16700 from 1989

    In natural light, the lume dots show light beige patina. Under UV light, the lume does not glow, nor reflect the light. You could probably say that the tritium gleams, but I find it not very obvious.

    That’s at least what I see, maybe you have another impression.

    2) Rolex GMT Master spare tritium dial

    In natural light, the lume dots and triangle shows a shiny custard patina. Under UV light, the lume does not glow, nor reflect the light. Essentially the same as sample No 1.

    3) Rolex 16570 black spare dial

    In natural light, the lume dots and triangle shows as shiny, almost orange patina. Under UV light, the lume shows pretty much the same results as example 1 and 2.


    4) Rolex 16570 white dial spare dial

    In natural light, the lume dots and triangle shows as a light beige, matt patina. Under UV light, I observed a slightly different reaction as the inner parts of the lume dots/triangle see to reflect the light.

    5) Zodiac Sea Wolf

    I chose the Zodiac Sea Wolf for comparison since it is one of my vintage watches which do not glow or reflect under UV light. The lume triangles show heavy patina under natural light, but as I mentioned I didn’t notice any reflection or glow. (The lume triangle on bezel however glows quite strong)

    6) Glycine Airman SST 1970’s

    Finally there is this interesting case of a 1970s Glycine Airman SST. Upon close inspection of the hands, the minute and second hand seem to be an old relume job, while the hour hand appears to be the original, albeit cracked lume. But none of the hands reflects or glow under UV light. The lume markers do slightly glow however. It could of course be that for the reluming of the minute and seconds, a nonglowing sort of paint was used.

    7) Freese Series 1

    The lume has a nice patina but looks quite different from the other dials in daylight when inspected by loupe. When activated with UV light, the lume glows lightly.

    Inspection under UV light is one of my standard inspection methods for vintage watches. But with the different behaviour of the dials inspected I am not sure how to make sense of it.


    So what is your interpretation of the observations above? Or did I miss an important aspect?


    I am looking forward to learning about your take on this subject.


    Best,

    Stefan
     
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  2. SkunkPrince Jan 3, 2021

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    There are two reasons lume won't lume. No more radiation, or the paint oxydizes. Tritium has a half-life of 25 years; couple that with oxydation, and you get nothing. That your UV source doesn't excite it bears this out.

    The half-life of radium might as well be forever; almost always lack of lume is because of paint oxydation.

    My personal experience with tritium gas tubes, about ten years is all you'll get between OMG IT'S A FLASHLIGHT to I can't see it glow any more.

    My night vision is reaaaaaally good so I can see radium lume most of the time after dark adaptation. Depending on the paint, the results can be anywhere from "there's lume?" to I can read my 1910 alarm clock no sweat.

    Glad you had fun with the black light but all of the results are idiosyncratic to the watches and doesn't really tell you much of a general nature.
     
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  3. Dan S Jan 3, 2021

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    The excitation or lack of excitation of these dials by UV is not related to tritium; it's the response of the particular phosphor formulation to UV or visible light excitation.

    Tritium was the power source originally intended to excite the phosphor. Tritiated polymer binder was formulated with phosphor particles (e.g. zinc sulfide) and other minor ingredients (e.g. pigment) to make the luminescent paint. When these watches were new, the plots were luminescent all the time, even in the total absence of UV or visible light excitation since the phosphor was excited by the radioactive decay of tritium. However, since tritium has decayed almost completely after several decades, the phosphor will no longer emit in the absence of external excitation by UV or visible light.

    Thus, any emission you see upon UV/vis excitation of these dials comes from the phosphor directly, nothing to do with tritium. Some phosphor formulations have degraded chemically and no longer respond to UV excitation. Other formulations still respond to direct excitation but die off after a few seconds. Yet other formulations die off partially after a few seconds, and then have a residual emission for several minutes. Different manufacturers used different phosphor compounds and formulations, and even changed them over the years. Rolex, in particular, changed their formulation significantly over time, from the 60s to the 70s to the 80s. Thus, knowledgeable collectors are well aware of how Rolex phosphors made in different eras should respond to UV light, but they're not always eager to post this detailed information on public forums, for obvious reasons.

    In the absence of this detailed knowledge, the most you can do is look for consistency between all of the lume on the dial and hands. Often you will see that one hand, or one marker responds differently, which gives away a relume. If the entire watch and hands have been relumed using paint that incorporates material recovered from old watches, then it will be quite difficult for you to detect the relume unless you have done tests on many similar watches.
     
    Edited Jan 3, 2021
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  4. SkunkPrince Jan 3, 2021

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    Just to elaborate a bit on Dan's good explanation, if UV excites the lume and it persists an hour later, that is almost for sure a relume using Luminova or its Japanese equivalent, whose name I don't recall.
     
  5. Foo2rama Keeps his worms in a ball instead of a can. Jan 3, 2021

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    Why is the freese101 watch not lighting up... I could have sworn they used vintage colored luminova...
     
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  6. Vintagewtchzilla Jan 4, 2021

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    Also don’t forget that not every uv lamp uses same intensity and wave length.

    Yes the freese one is disturbingly dead but i don’t know what basis is used as lume.
     
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  7. Davidt Jan 4, 2021

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    I can't speak for vintage Rolex, but as long as the remaining paint/phosphor/tritium compound is still in good overall condition (I.e. Not degraded to green mush due to moisture ingress) vintage Omega tritium dials from the 60's/early 70's always exhibit glow when excited by an external source such as a flashlight in my experience.

    This may be feint but in original Omega dials from this period it's always there.
     
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  8. Dan S Jan 4, 2021

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    Rolex lume from certain time periods is completely dead, and from before that period it is strongly excited. The 5-digit dials shown by the OP aren't old enough to demonstrate these changes.
     
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  9. Davidt Jan 4, 2021

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    I thought that was the case. I just haven't had first hand experience with enough vintage Rolex to comment.
     
  10. nitediver Jan 4, 2021

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    thanks for your comment!
     
  11. nitediver Jan 4, 2021

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    Thank you for your detailed explanations, this is indeed very helpful. I will keep on observing and learning.
     
  12. nitediver Jan 4, 2021

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    thanks, thats certainly the case. By looking at my vintage watches under UV light, it is clear that an vintage watch will not glow for such a long time, but only briefly.
     
  13. nitediver Jan 4, 2021

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    It actually lights up, but not so strong. you can see that from picture i posted, the hands glow quite bright, but the lume dots less.
     
  14. nitediver Jan 4, 2021

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    i might buy another UV lamp, as they are inexpensive, and look at the results again
     
  15. nitediver Jan 4, 2021

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    Yes, I have the same experience, and not only the Omega's, but most other vintage watches from the period as well. Thats why i was somewhat puzzled that the Rolex dials show a different reaction (or a lack of reaction) to UV light.
     
  16. nitediver Jan 4, 2021

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    thats good to know , at least the Rolex dials i posted the pictures of are not totally off the mark.
     
  17. Sherbie Jan 4, 2021

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    Cant add a lot to whats already been said, except that tritium has a half life of 12.3 years ( and not 25 yrs as quoted above)

    my 16700 from 1993 is completely dead to UV light btw
     
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  18. Linesiders Stripers, not snook. Jan 4, 2021

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    OP - you need to MAGNIFY and UV.

    SWISS-SPCG-Blue-Lume1.jpg



    I believe Rolex / Tudor / Omega used the same Lume compounds at some times, particularly the 66-69 period Rolex / Tudor / Omega lume looks very similar under UV and BIG magnification, they are also more likely to develop the same fungus in that same time frame. Remember back then outside dial manufacturers made the dials to the watch manufacturer's spec and likely sourced the lume compoiunds that were swiftly changing between 60 thru early 70s.
     
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  19. lexieb007 Jan 4, 2021

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    Great topic! I struggle with identifying tritium - even with the Blue UV technique and most sellers don't have a clue. Isn't the only real way to tell using a radioactive detector of some sort? Don't know how accurate it would need to be but all tritium would still be radioactive now on watch faces... even if it's decreasing... it would still be there...?
     
  20. lexieb007 Jan 4, 2021

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    This is totally the best explanation I have ever read on this topic. So given that UV is a test of phosphorous, are there any radioactive detector instruments a collector can use to actually measure if there is tritium present?