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Post by dapellegrini on Jan 24, 2024 20:19:03 GMT -8
Q: Do we know which vintage Seiko/Citizen branded watches used (or may have used) Radium-based lume?
I had read somewhere that the brownish aged lumes in some mid sixties Seikos might be Radium. I was also recently asked if the dial patina on an early 60's Silverwave pre-diver is radium burn. This got me wondering if we know which vintage models are known to use Radium, if any?
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Post by dapellegrini on Jan 27, 2024 13:42:45 GMT -8
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DanS
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Post by DanS on Jan 27, 2024 13:54:27 GMT -8
I was under the impression that Japanese watch companies avoided radioactive lume entirely, even tritium, so I'd be very interested in information about this.
Anyway, I find a Geiger counter to be useful, mainly to confirm original lume in early Swiss watches.
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Post by dapellegrini on Jan 27, 2024 15:16:24 GMT -8
What looks like "lume burn" on the dial of this silverwave, and the mono-pusher below it got me very curious
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DanS
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Post by DanS on Jan 27, 2024 16:15:20 GMT -8
Hmmm, I was assuming you were talking about earlier watches. I would be really shocked if Seiko used radium lume in the 60s. I've heard rumors about promethium.
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DanS
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Post by DanS on Jan 27, 2024 16:33:02 GMT -8
OK, I just quickly tested a bunch of my 1960s Seikos. Most were at background levels. However, a J12082 SilverWave did read noticeably above background, about 0.4 µSv/h. This is still really low compared to my typical radium watch, which would be at least 10x higher, but it's more than you would read from a tritium watch or a watch without lume.
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Post by dapellegrini on Jan 27, 2024 16:46:34 GMT -8
I kind of suspected that of the J12082. I am also now suspect of the Alpinist J13079, and wondering about the early 45899 mono pushers.
I read that the brownish lume on some 62MAS and 6105's is Radium (circa 66 or so).... Could be incorrect, not sure and I don't have either of those to test.
I am also curious with the Citizen 2812-Y divers with their huge brownish lume plots, and a few others. I am in the habit of at least cleaning up dials and replacing crystals, and thinking I need to be a little more careful than I have been with some of these mid and early sixties watches, maybe....
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DanS
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Post by DanS on Jan 27, 2024 17:05:34 GMT -8
My J13049 Alpinist is not hot, FWIW.
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DanS
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Post by DanS on Jan 27, 2024 17:09:18 GMT -8
Holy crap, my Daini 6105-8009 with the brown lume is super-hot. That is definitely radium.
The Silver Wave J12082 is not, I'm guessing it's promethium, just barely reads.
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Post by dapellegrini on Jan 27, 2024 17:17:44 GMT -8
Curious which Geiger Counter you have? Mine is taking forever to arrive, thinking of getting a different one instead...
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Post by dapellegrini on Jan 27, 2024 17:20:46 GMT -8
I read somewhere that the 6105 and 62MAS with brown lume were made for a specific US client that requested Radium lume... just don't remember where I read that now.
I wonder if there is just WAY less lume on the J12082... I can't find anything about when Promethium use started at Seiko, but the P dials were like from the 80's IIRC
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DanS
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Post by DanS on Jan 27, 2024 17:28:08 GMT -8
Regarding the J12082, I have plenty of Swiss watches with small radium lume plots, and they are still reading several µSv/h. If the J12082 is radium, they must have deliberately tried to reduce the amount to a very low level. I don't have any radium watches that low.
The 6105 is at least 10x higher.
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DanS
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Post by DanS on Jan 27, 2024 17:29:15 GMT -8
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Post by DanS on Jan 27, 2024 17:39:16 GMT -8
BTW, I checked my Olympic year monopushers, and they were not hot. Nothing above background.
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trilo
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Post by trilo on Jan 27, 2024 22:10:32 GMT -8
Hmmm, I was assuming you were talking about earlier watches. I would be really shocked if Seiko used radium lume in the 60s. I've heard rumors about promethium. Atleast Citizen used Promethium around 1975 to 1980. Citizen dials that have it, read P-Japan-P. They ditched it due to its poor half-life.
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DanS
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Post by DanS on Jan 28, 2024 7:22:08 GMT -8
Hmmm, I was assuming you were talking about earlier watches. I would be really shocked if Seiko used radium lume in the 60s. I've heard rumors about promethium. Atleast Citizen used Promethium around 1975 to 1980. Citizen dials that have it, read P-Japan-P. They ditched it due to its poor half-life. And obviously I was wrong about the radium, after measuring my 6105. The Silver Wave is still a bit of a mystery, with just a small, but measurable emission. Here's a photo BTW. Notice that the lume on hands and dial seem to be different. I guess everyone knows what the Daini 6105-8000/9 looks like. Just like a normal one with brown lume.
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trilo
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Post by trilo on Jan 28, 2024 7:54:16 GMT -8
Related to radio active materials in general, all promethium Citizens I have had, have had a nice colour on them. Here's an example from 1979.
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Post by dapellegrini on Jan 28, 2024 9:30:00 GMT -8
From TOF, this 6117-8009 from 1968 also uses Radium: EDIT: The meter I have on order should arrive later in the week. I have a few different Silverwave variants I want to check, and several others. Will share results here.
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Post by dapellegrini on Jan 28, 2024 10:24:33 GMT -8
What month/year is your 6105-8009? I think Radium was illegal after 1968, so I suspect that might be the safe line. This Silverwave has green colored lume throughout, but again, the dial looks burned around the lume plots, making me wonder if some green lume like this could also be Radium: Then there are others that looks like the lume is all brown
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DanS
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Post by DanS on Jan 28, 2024 10:49:09 GMT -8
What month/year is your 6105-8009? I think Radium was illegal after 1968, so I suspect that might be the safe line. That one is April 1968.
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