Tritium Question

[aleiberman]

How come the tritium on my Rolex dial lights up only after a few yours in the dark, and it's not immediate. Whevener I wake up it is elluminating. I don't know how long it takes to get to this point of working, but i'm wondering why it works like this.

Thanks,

Aaron

[Andad]

As your eyes become accustomed to the dark so the tritium lume looks brighter?

[bb3188]

Originally Posted by aleiberman

How come the tritium on my Rolex dial lights up only after a few yours in the dark, and it's not immediate. Whevener I wake up it is elluminating. I don't know how long it takes to get to this point of working, but i'm wondering why it works like this.

Thanks,

Aaron

hi Aaron, Isyour watch from the 60's 70's or eighties ?

[aleiberman]

my watch is 1986 GMT

[Racer X]

I think they used luminova in the 80s, not tritium.

[Andad]

Luminova or tritium?

My answer would still be the same.

[sleddog]

Originally Posted by directioneng

As your eyes become accustomed to the dark so the tritium lume looks brighter?

Originally Posted by directioneng

Luminova or tritium?

My answer would still be the same.

Yep,that's my take as well!

[bb3188]

dont thinks it tritium...i thought the last batch were characterised by total lose of llume function by now.............

[Gugnunc]

Hi Aaron,
Interesting all this talk of the properties of old tritium lume. Your watch is now 24 years old so the original light output of the tritium fuelled components should be down to about 25% of its original value, however I understand that batches of tritium paint varied widely and that using the 12.3 year half-life of tritium and then doing the calculation does not always coincide with what is observable - my 40 year old lume is still JUST glowing in total darkness, but not enough to read. Whatever is happening it cannot be that the light output of your watch is changing during the hours of darkness, it can only be that the instruments used to measure it (that is your eyes) have become much more sensitive to weak light whilst having little or no light entering them. There is one caveat to this however - if you leave your watch close to some light source overnight then it will, but only VERY briefly, act like luminova and glow quite strongly - mine does this but I cannot explain the physics which allows this to happen.

[PhilM]

They used tritium up to around 1999 as that's when the change over occurred, so your dial should be tritium or it could be luminova depending if the watch was serviced at any point by RSC and it had the dial and hands replaced.

Quick way would be to post an image... or at the bottom of the dial below the 6 hour marker, does it have the following T <25 (not 100% accurate, as there's service dials that are labelled like this but are actually luminova)

[bb3188]

Originally Posted by Gugnunc

Hi Aaron,
Interesting all this talk of the properties of old tritium lume. Your watch is now 24 years old so the original light output of the tritium fuelled components should be down to about 25% of its original value, however I understand that batches of tritium paint varied widely and that using the 12.3 year half-life of tritium and then doing the calculation does not always coincide with what is observable - my 40 year old lume is still JUST glowing in total darkness, but not enough to read. Whatever is happening it cannot be that the light output of your watch is changing during the hours of darkness, it can only be that the instruments used to measure it (that is your eyes) have become much more sensitive to weak light whilst having little or no light entering them. There is one caveat to this however - if you leave your watch close to some light source overnight then it will, but only VERY briefly, act like luminova and glow quite strongly - mine does this but I cannot explain the physics which allows this to happen.

Phil, my watch from the 60s glows a bit at night but the 70s onwards is dead as .......
for the dial to glow late at night......might it be luminova replacement dial ?

Aaron, a picture of your dial might help

[PhilM]

Mark, yours might be radium then as that was used in the early 60's... tritum didin't start appearing until the mid 60's, and the watches that I have seen that have had radium applied to the markers all glow still

[bb3188]

Originally Posted by PhilM

Mark, yours might be radium then as that was used in the early 60's... tritum didin't start appearing until the mid 60's, and the watches that I have seen that have had radium applied to the markers all glow still

Phil, ive got a 53 explorer with radium that ever so slightly glows at night.
the watch I have from the 60's is a gilt dial 5513 with the earlier tritium swiss t<25 ..In my experience theearlier trit glow but the later ones in the 70's didnt.....( i had a red sub ) thats totally dead on the lume.......... I wonder if the mix for the tritum lume changed in the eighties...which could explain the late night glow.....or could be a service replacement luminova....

I guess some pics by the OP could answer the question........:)

[PhilM]

You can only guess with lume, as it varied so much, not just over the years but even from batch to batch and watchmaker to watchmaker... I don't think, or I haven't seen from Rolex any copy \ instructions on how it was made or mixed.

[dsio]

This may sound like an odd question, but is tritium lume still available to purchase? Are there still some old school independent watchmakers that don't believe in health and safety laws and still do tritium relumes?

Just never heard it mentioned and would have imagined that given the number of vintage enthusiasts there are, someone may have risked wrecking a dial by having a tritium relume done.

[PhilM]

It's not available to purchase anymore, it was banned for use in watches in it's free format, although you can buy tritium tubes which are sealed units

[dsio]

Fair enough, but aren't there still military watches that use it?

[Gugnunc]

Mark and Phil,
Tritium was used from the early sixties hence all the furore about underline dials and overprinting with T<25 etc. etc. which went on at that time. Easy enough to differentiate between an old tritium dial and one utilising luminova: subject it to very bright light for an hour or so and then take it into a totally dark place - if it's readable after five minutes then it's luminova, if not then it's exhausted tritium. Also, if it is tritium then it should have the "T" marking on the dial.

[PhilM]

Originally Posted by Gugnunc

Mark and Phil,
Tritium was used from the early sixties hence all the furore about underline dials and overprinting with T<25 etc. etc. which went on at that time. Easy enough to differentiate between an old tritium dial and one utilising luminova: subject it to very bright light for an hour or so and then take it into a totally dark place - if it's readable after five minutes then it's luminova, if not then it's exhausted tritium. Also, if it is tritium then it should have the "T" marking on the dial.

I think that was what we've just disussed above

[dsio]

I'm guessing radium lume isn't available by the pot anymore either? Nothing on ebay by the looks.

[PhilM]

Originally Posted by dsio

I'm guessing radium lume isn't available by the pot anymore either? Nothing on ebay by the looks.

No afraid not, that stuff is worse the tritium

[therolexguy]

Originally Posted by PhilM

Quick way would be to post an image... or at the bottom of the dial below the 6 hour marker, does it have the following T <25 (not 100% accurate, as there's service dials that are labelled like this but are actually luminova)

Very true. My 1680 is an example of this.

[dsio]

Does your 1680 there have a white date wheel?

[aleiberman]

Mine is the original tritum dial (SWISS-T<25)

[bb3188]

Originally Posted by aleiberman

Mine is the original tritum dial (SWISS-T<25)

Pics ?????

[PhilM]

Originally Posted by therolexguy

Very true. My 1680 is an example of this.

Lovely example

[Badfish179]

The reason you see the glow when you wake up is due to your night vision. When your eyes are exposed to any light whatsoever during periods of darkness it destroys your night vision. Because your eyes are closed for a few hours your night vision is optimal;thus, enabling you to see the faint glow of the tritium on your watch's face. I have a 5512 from 1967 all original. I can see the lume glow faintly at night and be "fairly sure" what time it is.