DanS info above is pretty good. John Harris did some other good stuff on VRF and MWR years ago.

I am sure there are ultra sensitive devices that can detect some radiation from old tritium and are better able to measure than consumer grade equipment.

Consumer grade equipment (GMC or RADEX for example) might be able to see some activity above background levels. But they cannot do any detailed analysis and don't always measure all forms of radiation. I am not a scientist nor a nuclear engineer - I'm a geek.

Background levels in my area are around 0.06-0.08 microsieverts per hour (μSv/hour) . Sometimes if I maneuver the detector just right over a 61 Tudor 7928 I can get readings around 0.11 microsieverts (once 7 years ago I had 0.25). I have a 7924 with some radium that reads over 2.0 microsieverts and a 54 Blancpain that pegs my meter at its maximum of 10.00 microsieverts. If you saw Chernobyl on HBO (or better, read Midnite in Chernobyl) you saw a lot of talk of Roentgen / hour. The joke 3.6 Roentgen, not good, not terrible - well 3.6 Roentgen is 3600 times the maximum reading of my GMC or my Radex.

Tritium has a half life of roughly every 12.5 years so in 25 years tritium will be roughly 25% as effective as day one. I have a 2000 something Marathon TSAR with trit tubes that is no longer bright enough for use out at night. I have a 1980 Snowflake that was on the nightstand and I woke up, pitchblack new moon night, and saw a faint glow on the dial. So as a test I keep the watch for 24 hours in a closed pelican box so there would be zero external UV influence, took into the bathroom, put towels on the floor / door gap to block light leakage, spent 10 minutes adjusting my eyes to the dark. Open the box and I can faintly see the lume on an otherwise dead looking dial. I highly recommend people try this with their old Tritium watches. You might be surprised.

 

Yes, I've noticed this too. if the phosphor is still good, you can often see faint luminescence if your eyes are well acclimated.

 

thanks. So if your 16700 shows no reaction to UV light, and mine from 1989 neither, we see a pattern

 

Some are completely dead even though perfectly legit and this is more common from later 70s and on. You can have two watches, same year and model, with different reaction or no reaction at all.

 

thanks, thats good to know

 

excellent observations and information. BTW, I watched Chernobyl series on long haul flights....pretty scary. I ordered a dosimeter, (consumer type), so will do some tests on my vintage watches.

 

so no pattern then. Makes it kind of difficult. So how you make sure it is not a redial? I read that genuine old rolex dials are stripped, repainted, printed and faux tritium being applied.

 

I need another device then. - loupe and UV light. Actually i have a Loupe System with light ring, i think it has UV light, but i havent tried yet. Let me see.

 

I have a hard time believing that only the lume in the hands grow mould/fungus, when there is also paint and varnish (i.e. an organic food source) on the dial. In that sealed environment I would expect mould to form evenly inside that humid environment.

The blackness I have seen in lume could be interpreted as an ingress of iron ions from the hands into the paint (there can be a lot of migration of ions through paint - this is something I know from my real world work) reacting with sulphides that originated with zinc sulphide in the luminous paint forming iron sulphide which is black. I hope that makes sense as an additional interpretation.

 

What I know is that it looks like fungus / mold. What I have not done is scrape a sample off one of my dials and send it to Fungus Control ; )

It is fairly common on Rolex, Omega, & Tudor dials in 66-69 Time frame. I would LOVE to be proven wrong and as the truth matters, find out what it actually is and if there is any mitigation.

 

thanks for your comments. My interpretation is that the paint doesnt grow any fungy because it may contain lead, cadmium or an other stabilizer.. it was not uncommon in the 1960s as i know from my previous job.

 

It also spreads/grows like mold, and is often correlated with moisture/humidity. TBH, I think it's pretty well established that one often sees mold on lumed hands and dial lume plots. That's not to say that there aren't other types of discoloration.