re: Wristwatch

[mturner@xxxxxxxxxxxxxxx (Marc Turner)]

     >>the "indaglo" stuff
     >>i think it uses Radium
     >>
     >>jade
     >>*
     
     >If you have to push a button to light up the dial, it ain't radium.
     
     
     A long time ago (in a galaxy far far away) watchmakers used radium on 
     the hands of some watches to make them glow in the dark.  Radium was 
     mixed with a phosphorescent paint, and radiation from the radium made 
     the paint glow.  An unfortunate side-effect was that many of the 
     people who worked painting the watches died of cancer (apparently 
     mostly because they occasionally licked their brushes to sharpen them, 
     ingesting some of the radium).
     
     When people became more aware of the health risks, the use of radium 
     in watches stopped.  There were still watches made for awhile (and I 
     believe there may be one or two still being manufactured) that used a 
     sealed "Tritium" readout.  This is indeed radioactive but of a type 
     that can't penetrate even paper very well - it is only dangerous if 
     you somehow got the capsule out, crushed it, and ate it.  You can 
     recognize this type by a green "Indiglo" type glow which is on all the 
     time - you don't push any buttons.  It isn't quite as bright as 
     Indiglo but doesn't take any electricity - I had one once and it was 
     very nice.
     
     The Indiglo readouts use an electroluminescent technology similar to 
     the lighting panels used behind some laptop computer displays.  It 
     isn't radioactive and I doubt it has any after-glow that would affect 
     film when it is not activated.
     
     -- Marc
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