Re: Radium on Luminous Dial Watches

[Wayne Schlitt <wayne@MIDWESTCS.COM>]

In <3.0.1.32.20011108143748.010974ec@peseta.ucdavis.edu> "Otto G. Raabe" <ograabe@UCDAVIS.EDU> writes:



> Does anyone know approximately how much Ra-226 was present on the face of a

> typical radium-dial wrist-watch used during the first half of the 20th

> Century?



Hi.



I'm a watch collector and I'm interested in the subject of

radioactivity of watch dials.  I joined list because my web searches

turned up discussions on this subject in the archives.  You might want

to check out the archives, I found the old postings useful.  ( see

http://www.vanderbilt.edu/radsafe/ )





>From what I can tell, the amount of radium used varied widely.  Not

only did it vary over the years, but from watch to watch.  Basically,

for many years, safety was not a concern, the balance was between

adding enough radium (and anything else that was radioactive enough)

to make the watch glow and not adding so much as to be a waste of

money.  After the sad story of the "Radium Girls" came out in the late

1920s, safety became more of a concern.  In general, the earlier the

watch is, the hotter it is likely to be.  The exception appears to be

military watches, made during WWII.  They can be quite hot.



I maintain a website on the subject, which can be found at:

http://www.midwestcs.com/elgin/help/luminous_dials.html



Comments, corrections or suggestions would be appreciated.





The short answer as far as safety goes is that if you just have one

watch, you are probably just fine.  Just don't open up the watch and

disturb the paint dust and don't sleep with the watch on.  If you are

a watch collector with lots of these radium dial watches, or if you

are a watchmaker who works on them, you probably should think about

this subject a lot more.





-wayne

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