Seiko 7A38 - by the numbers



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Michael Heathcote
Posts: 3

An observation really.

I don't normally wear my Seiko overnight but last night I woke in the middle of the night, and it was impossible to tell the time, the watch face was totally black.

I can just remember when my Seiko was new and everyday wear, it was lit up nice and clear even it total blackness.

I guess it must be due to the half-life of the illuminous paint that was used, and it has simply run its course.

Shame really.


7A28-7020 owner

February 26, 2017 at 6:19 AM Flag Quote & Reply

Site Owner
Posts: 13276

Not that it particulary worries me, Michael. Nor is it a great surprise. The half life for Tritium (as used on most* 7Axx's) is 12.5 years - and all of these watches are over 25 years old now - most coming up to 30. Just try googling Life of Tritium lume and you'll find umpteen threads discussing this on other watch forums. ;)

*The notable exception being the 7A28-7120 RAF Gen. 1 which uses Promethium lume.

February 26, 2017 at 6:37 AM Flag Quote & Reply

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