How to identify a relume by UV light inspection?

Sherbie

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

Sherbie

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

Linesiders

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.

Linesiders

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.

Linesiders

OP - you need to MAGNIFY and UV.

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.

they are also more likely to develop the same fungus.

nkhandekar

I have a hard time believing that only the lume in the hands grow mould/fungus, when there is also paint (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.