Sciencemadness Discussion Board

How hot old watch and clock?

NEMO-Chemistry - 16-11-2017 at 18:11

My mum has my dads old watch from the late 60's/early 70's, and a older bedside clock. Having read a few posts here, it dawned on me they might be radioactive, ok not a big deal...

But how hot are items like that, likely to be? Both are up in the atic and not bothering anyone, the clock only has a very faint glow now, but the watch is pretty good still.

What are the likely sources used?

Sorry for the questions i am just interested.

macckone - 16-11-2017 at 18:33

Radium dial clocks were quite popular during that era.
Given the half life of 1600 years, they are probably pretty close
to as bright as the day they were made barring a breakdown of
the phosphor.

Bert - 17-11-2017 at 00:08

Radium DOES destroy the Zinc zulfide phosphors that were typically used with it.

My grandfather's WW I altimeter and cockpit clock are still mildly radioactive, but do not glow visibly at all.

The sealed instruments aren't particularly dangerous, the dust inside them with the Radon daughters potentially is, though. Found out all about this when I tried to find an instrument shop to fix the altimeter when the bellows quit working.

Texium - 17-11-2017 at 09:44

Quote: Originally posted by NEMO-Chemistry  
My mum has my dads old watch from the late 60's/early 70's, and a older bedside clock. Having read a few posts here, it dawned on me they might be radioactive, ok not a big deal...
That sounds far too late for the use of radium paint. Radium was phased out in the 50s. Promethium was used for a time after that because it was much safer, but since it has a much shorter half-life, pretty much anything painted with promethium is long since dead, converted to stable neodymium and samarium.

NEMO-Chemistry - 17-11-2017 at 11:31

Better yet i found a 1980's led watch, a red one lol. reading up on them the batteries died within weeks

Radium212 - 2-1-2018 at 14:29

Seems like promethium maybe.

TheNerdyFarmer - 2-1-2018 at 15:55

If you still believe that it may be radioactive. There are many cheap Geiger counters and dosimeter for about 25 us dollars on eBay. I would recommend getting one of these. They won't be very sensitive, but they will probably tell you if something is radioactive or not.