CR
[Moderator]
4018
6542 (and 1675) Radiation Measurements
Several WPS threads were really helpful, and fun to read, in my desire to learn a bit more about this subject. There's this one (Rolex and Radioactive Material), this one (Rolex and Radioactivity), this one (Rolex: Is the geiger counter a reliable tool in evaluating the radioactivity on a dial?), and this one (No better way to start than a 6542).
After reading those threads, I got curious about this 6542 (c.1958) and 1675 (c.1961):
Does this 6542 contain Strontium-90? I was hoping for a "no" answer, given what I read in the "Rolex and radioactivity" thread above and elsewhere.
And what would my exposure be from wearing these watches from time to time -- a natural question?
So I met up with an old college friend at a nuclear reactor, to find out.
The first thing we did was answer the question, "What radioactive material was used in these watches? And was any Strontium-90 used?"
This involved a "Canberra spectrometer," whose thick lead walls you can see here:
It appears that just Radium-226 was used (on both watches), with no Strontium-90 detected.
Now that the spectrometer answered (to a reasonable degree) the question of what material was used, we measured the levels with this Ludlum Geiger counter -- a fitting device for this watches, since it's around the same age:
We took front and back measurements for each watch. And of course, we'd expect much lower readings on the back versus the front.
To simulate wearing the watch, I pressed the caseback against the Ludlum's pancake probe when taking the reading. I did the same for the crystal side, noting that levels drop off substantially when you move the watch even a few centimeters away from the probe.
So what did we find?
The Ludlum measures radiation levels in millirems/hour (mrem/hr).
The 6542 measurements were 12-15 mrem/hr at the crystal and 0.5 mrem/hr at the caseback.
The 1675 measurements were half of the 6542's -- 5-6 mrem/hr at the crystal and 0.25 mrem/hr at the caseback.
One millirem/hour equals 10 microsieverts/hour (uSv/hr).
This means the 6542 clocks in at 120-150 uSv/hr at the front (sleeping with the crystal against your face), and 5 uSv/hr at the back (wearing it on the wrist).
Of course, when wearing a watch, your whole body isn't being exposed to these levels. It's just one extremity. That matters when assessing health risks.
Speaking of health risks, Justin6542 posted this reference guide in a prior thread:
This was a fun exercise!
Any thoughts (or corrections I should make to my math or other information)?
Disclaimer, in case it's not obvious: I am NOT a nuclear engineering expert!
6542 (and 1675) Radiation Measurements
Several WPS threads were really helpful, and fun to read, in my desire to learn a bit more about this subject. There's this one ( Rolex and Radioactive Material ), this one ( Rolex and Radioactivity ), this one ( Rolex: Is the geiger counter a reliable to...
Very informative thread on the Rolex 6542 and dial materials.
I guess we can all rest assured these watches safe to wear. My argument without the science you presented is that there would have been a lot more litigation around these watches if the really posed a danger. But each person is free to assess their indivi...
Excellent point, Tony. From what I've read, radon gas buildup may be a legitimate though rarely discussed concern.
Jack Forster wrote about that some years ago, and I found a 2012 article entitled Radium dial watches, a potentially hazardous legacy? that discusses this in some depth. I'm curious about this and want to look into what it would take to measure that at ho...