16750 Dial Question

[FrmrHoss]

This may be a dumb question and have searched the forums (but maybe not well!) so apologies in advance. Would any matte dial 16750s not have any luminous material on the dial? I have a pretty early S/N reference 16750 that just got under a UV light for the first time with basically no reaction at all....

Tbh I was a bit surprised since I had previously had an '82ish GMT that, while I never got under a UV light, had taken hiking before and in the middle of the night with no natural light was still able to make out a faint faint glow.

[037]

It could be an unpainted service dial or the lume was washed away by a watchmaker. Without seeing it we can only speculate.

Can you post a photo?

[springer]

The markers are painted white on the 16750 matte dials. The markers, absent any tritium being present, appear white in color when viewed under UV lighting - pretty much the same color as markers that still retain their tritium lume. Obviously this can sometimes fool the casual novice collector as to whether or not a dial has any lume.

As far as 16750 dials being produced without lume, this would be something that I have never seen or heard of before.

[FrmrHoss]

Originally Posted by 037

It could be an unpainted service dial or the lume was washed away by a watchmaker. Without seeing it we can only speculate.

Can you post a photo?

Yeah, will post some photos later tonight.

Originally Posted by springer

The markers are painted white on the 16750 matte dials. The markers, absent any tritium being present, appear white in color when viewed under UV lighting - pretty much the same color as markers that still retain their tritium lume. Obviously this can sometimes fool the casual novice collector as to whether or not a dial has any lume.

As far as 16750 dials being produced without lume, this would be something that I have never seen or heard of before.

Hmmm, but they would still have some glow after being exposed to UV lighting right even if they appear white under UV light?

Appreciate the feedback.

[037]

Originally Posted by springer

As far as 16750 dials being produced without lume, this would be something that I have never seen or heard of before.

I've seen a couple Sub matte service dials without lume yet applied but not specifically the 16750. That's why I said it was speculation on what we might be looking at above.

[FrmrHoss]

Here are two. I have a macro lens I can take some shots with tomorrow just left it at the office.


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[037]

Looks like there's tritium on the dial to me.

Great looking watch, btw.

[007Sub]

some tritium just wont respond especially from that era. If the markers are creamy in color then there's tritium (which it looks like there is).

[springer]

Originally Posted by FrmrHoss

Yeah, will post some photos later tonight.

2

Hmmm, but they would still have some glow after being exposed to UV lighting right even if they appear white under UV light?

Appreciate the feedback.

No. Shut the light off and there is no glow. In my last post I was referring to color under UV lighting not glow.

[R.O.L.E.X]

Tritium has a half-life of around 12 years.

[FrmrHoss]

Originally Posted by springer

No. Shut the light off and there is no glow. In my last post I was referring to color under UV lighting not glow.

Sorry for being dense John - are you saying the matte dials from that era just have painted white markers and should not glow? Or it something in between?


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[FrmrHoss]

Originally Posted by R.O.L.E.X

Tritium has a half-life of around 12 years.

But that just means half of it decays over 12 years. So if you’re talking about a watch from 79, it would have roughly 1/8th the original tritium content I would think.


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[FrmrHoss]

Originally Posted by 037

Looks like there's tritium on the dial to me.

Great looking watch, btw.

Thanks man - I do love it, just trying to learn some more about these dials and stop being so ignorant


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[037]

Originally Posted by FrmrHoss

But that just means half of it decays over 12 years. So if you’re talking about a watch from 79, it would have roughly 1/8th the original tritium content I would think.

Not quite. Assuming 12.3 years as the half-life for tritium, after five half-life cycles (for example) you'd be at 23.83125 years. It reaches effective zero in less than 25 years since the decay rate is logarithmic. That's in part why it says T < 25.

12.3 + (12.3/2) + (12.3/4) + (12.3/8) + (12.3/16) = 23.83125

So, a watch from 1979 definitely won't have enough active tritium to illuminate the paint.

Hope that helps.

Originally Posted by FrmrHoss

Thanks man - I do love it, just trying to learn some more about these dials and stop being so ignorant

Sure thing.

[springer]

Originally Posted by FrmrHoss

Sorry for being dense John - are you saying the matte dials from that era just have painted white markers and should not glow? Or it something in between?


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You asked if would be possible for a 16750 dial not to have any tritium on it. The dials never came from the factory without tritium - if it did - it was a mistake.

The markers are painted on the dial and then the tritium is applied over the painted markers. (If all the tritium is missing and has been washed away, you would just see the white painted markers.) If all the tritium is missing, and you light the dial up with a blue light, they will look white. Additionally, if the dial still has tritium on the markers, and you light it up with UV, the tritium markers also look white. 16750s still containing their tritium could have a different tint under a blue light but on most occasions, it will look white. Lastly, tritium markers from 16750s should not glow once excited by UV light or a regular light once the light is shut off.

[swish77]

Originally Posted by springer

You asked if would be possible for a 16750 dial not to have any tritium on it. The dials never came from the factory without tritium - if it did - it was a mistake.

The markers are painted on the dial and then the tritium is applied over the painted markers. (If all the tritium is missing and has been washed away, you would just see the white painted markers.) If all the tritium is missing, and you light the dial up with a blue light, they will look white. Additionally, if the dial still has tritium on the markers, and you light it up with UV, the tritium markers also look white. 16750s still containing their tritium could have a different tint under a blue light but on most occasions, it will look white. Lastly, tritium markers from 16750s should not glow once excited by UV light or a regular light once the light is shut off.

x2. And the photo above of the 16750 under UV looks similar to how my 5512 reacts under UV. Take away the UV, and no glow.

[FrmrHoss]

Thanks guys. Appreciate your time and input on this!