Dear OF'ers

apologies for the stupid question, but I would welcome a schooling from knowledgeable people as I can only find contradictory info on the internet (for a change...). Every time you take a watch to the "pros", they pull out the magic light... what for?

What can one check with a UV lamp ON A WATCH DIAL/HANDS (for @Vitezi ) other than the very existence of some luminescent material? Do different luminescent materials "glow" differently under such "light"? What are the main uses of these seemingly-ubiquitous-in-connoisseurs-circles UV lamps?

Thank you

Paul

 

Cat pee. And, er, other bodily fluids.

 

Thank you. I have updated the thread title to remove any ambiguity

 

Uranium glass aka vaseline glass looks cool under UV.
Scorpions, the big black ones.

 

I have the feeling this thread is going nowhere

 

What are the main uses of these seemingly-ubiquitous-in-connoisseurs-circles UV lamps?
To get a tropical dial tan

 

Well, it's going nowhere, but at least it's funny

Would still like to learn something as opposed to just get a laugh, though

 

That old radium doesn't glow much (if at all,) repainted radium is kind of bright, and promethium is like a Christmas tree?

 

Would have been easier to have a beer and play with a lamp and different kind of watches. You will only learn when you see differences live.

 

I did... And it was anything but obvious to my untrained eyes Hence me asking.

Care to share the knowledge you have acquired?

 

Certainly, with a beer.

 

warum nicht after all? Looks like this thread isn't getting much engagement anyway... which is interesting as pretty much everyone a bit serious seems to carry his UV flashilight to "evaluate" watches.

Thanks mate

Paul

 

I personally use it to check that the tritium is all uniform in color and texture and lights up “in sync”. A repaired hand or marker will give itself up under black light, no matter how good it looks to the naked eye.

 

I am no pro, but things I look for are

1) the intensity of glow when the light is on (not as important as #2 imo, but can show something as in the case above)
2) the intensity of glow and the duration of the fade after turning the light off.

Here are 4 Seiko 6139's. They all are a similar age (1969), and 3 of them have near perfect and matching lume on the dials and hands, one has some patination (bottom right). Here is the fade-off after 30s.



What does this suggest? To me this suggests that the dials / hands are all matching, which is what I would expect if they were lumed in the same way with the same substance at the same time. The bottom right one is patinated, so the glow is less, which I too would expect.

Fade duration normally indicates material used (and this is a rough guide from observation whilst whipping out the UV light on watches) so should also be a hint as to the period (i.e. 60's dials shouldnt glow for hours).

Radium : almost instant fade.
Tritium : in the order of seconds to a minute or so
Modern Lume : hours.

Now the thing is to know the watch you are looking at. Not all watches had hands and dials lumed in the same factory or in the same way (i.e. hands and dial may have been lumed differently). Hell, I have a modern watch whose hands and dial lume glow differently to each other (its about 2 years old). This also happened in the past too. So it all really depends on what you are looking at.

Also worth mentioning : modern redialers can mimic tritium. So the glow and texture can even be similar. Its really not an exact science.

 

One wants to know if they are dealing with radium

For ones at home it's a nerd thing.

I actually use mine a fair bit for charging lume on fishing jigs and lures used at night for squid and deep reef fishing

 

@eugeneandresson summarized it pretty well. If you can get a uv light and a loupe together you will also see differences in the texture of the lume and can often call the difference between original lume and relume.

 

Not forgetting that on vintage watches the lume on the dial may have been done by dial manufacturer and hands may have been done by another company that supplied hands as this was common in the day.

 

not totally fair as the lume can be observed for a little longer with the eye than the (phone) camera... but you get the idea.

https://photos.app.goo.gl/7CgD8CjrXbnc37Ty6

 

Thanks Gentlemen, I'm slowly getting it.

Especially @GuiltyBoomerang and @eugeneandresson for going the extra mile of taking pics and not being patronizing.

Yesterday we were with a couple of friends playing with watches. Some of the indices on the older watches (early 60's) had lume that was barely glowing with the UV, and only in "some" parts of the luminescent material, tiny little dots within scattered across the lume'd surface. Think speedy long indices, and three shiny dots scattered across the (ca) 5sqmm 9 o'clock hour marker. Net, not homogeneous at all within the same index... does it mean that within the same location of lume, different "bits" can age differently? Was the mix done poorly, or is it a normal chemical/physical reaction?

Thank you,

Paul

 

Based on my limited experience, lume like this, where the bits that glow are uneven and scattered is often a sign of a relume. Original lume is more uniform and evenly distributed. You can really see it under uv with a loupe.