Understanding "T<25" history, sequence

[007Sub]

Originally Posted by jlovda

As an amateur photographer, I have the following question. If Tritium has a half-life of 12 years, can it be assumed that the light output of the dial would be down 1 f-stop after 12 years, 24 years = -2 f-stops, 36 years = -3 f-stops, etc? Is the output of the ZnS linear as the Tritium decays or is a certain amount of bombardment required to glow at all? Does the ZnS itself deteriorate over time from bombardment?

Also, what actually causes older dial markers to fade to an ivory and then light brown shade? Is this an unalterable process or is it related to exposure to UV?

John

This is a good question... i wonder if putting some kind of UV coating on the crystal of a watch would limit and/or slow the aging process of the tritium paint.