Tritium lume markers-CREDIT JEDLY1

[mike]

before it gets lost in the bevel thread..and it is another thing that quite a few myths exist around. to summarise the discussion to date from years of study and debate over on VRF and elsewhere... a quick précis.

On Rolex watches tritium was introduced as a safe alternative to the previously used radium circa 1962, and is most commonly identified on the dial with swiss < 25t until it was discarded for the safer luminova in the 90's - i wont digress into the whole underline thing.

Although we simply call it tritium it is actually a compound containing a phosphorous substance and within that overall compound there is some tritium which acts as the power source for the phosphorous material ((like the battery).

From the introduction onwards it appears that various different 'recipes' were used for this compound, as well as different physical applications to the dial.

If you line up a whole load of watches in consectutive years you can actually see the pattern of how these mixtures/applications changed, even more so if you use an ultraviolet loupe and can see the make up of the marker and its response to light.

what you tend to see - not as an exact science :

1. up until about 64/5/6. the gilt dials... markers tend to be quite domed and textured in their appearance and when exposed to a strong light source the luminous material will glow green for a short time. Put a UV loupe on them and it is a uniform green finish.

2. 67/68 first of the matt dials.. this seems to have been a cross over period in the manufacturing approach, two extremes along side.. very domed markers like half maltesers for those who know what they are, glow green for a short time if exposed to a strong light source. I guess this is why there are often so many posts requersting opinion from watches in this period as they seemt o create the most confusion.

OR

very flat very thin layer completely dead to light exposure.

3. 68-74/5 - greatly reduced amount of compound applied ,flatish application of the mixture nearly always dead to any light stimulation. you get used to see-ing how the application was made on different models in this time period, some with a very weaved texture., some dead flat. Usually greenish/bluish crystals present as the only glow under a UV loupe. tends to yellow over time.

4. mid 70's back to a more textured appearance with a bit more dome to the markers, often orangey crystals are the only things stimulated as visible under UV loupe. Does not tend to respond to light stimulous but there appears to be some small amount of power left in the tritium and often in a dark room in the middle of the night the markers/hands can be read/seen. Examples often tends to orange/brown as well as just yellow as they age.

5. early 80's - new mix again flat, glossier, no repsonse to light stimulous but often some power left in the tritium that will give some luninous in darkened conditions once the eyes have become accustomed.


thats pretty much where we leave vintage.


the tricky bit is the 60's stuff that still glows green, if you pick up a watch and it does , then it doesnt neccessarily mean its relumed, neither does it mean its OK, the relume question tends to be the trickiest (unless its just a crap job of physical application), is often virtually impossible to address over the net, and even in hand can leave a room split down the middle.

what we do know for the late 60's/70/870's stuff is that it appears from all the long term stored examples discussed, is that left to its own devices the tritium based compound will age, and gain patina. From what we have seen and a few experiments conducted we see that light has a bleaching effect on the mixture which slows the development of patina and keeps it light.

the tricky bit with this is that the mixture can also gain patina through moisture ingress ( especially for example in a humid climate). The trick here is to look for any other seconday signs of mositure.. staining, corrosion etc ..

Ok, not an authorative guide, and off course there will be examples that maybe buck this, it is after all Rolex.