Learn more physics!
Thank you for this wonderful Q&A site.
I understand that Timex received the patent for the Indiglo® nightlight. Timex uses the Indiglo nightlight technology to light up the dial.
My concern was the "glow in the dark" button on the Timex watches. I know that some of the "glow in the dark" substance (especially watches) uses radioactive materials such as tritium. Does the "glow in the dark" button on the Timex watches contain tritium or any other radioactive materials?
- Steve Boson
Hi Steve- You can still get watches with tritium in small vials on
watch hands and to mark the hour locations on watch dials, but this
isn't what makes Indiglo® dials glow. Since the radioactivity in
tritium cannot be turned off, it would not be used anyway in a watch
with a glow-in-the-dark switch. The 'off' setting would have to somehow
shield the phosphor from the radiation from the tritium, which would be
a big technical nuisance for an inexpensive watch.
(published on 10/22/2007)
Follow-Up #1: radioactive watches
I have a timex watch from 1974,
I am worried about it because a think that have tritium or radium on the dial.
Is it posible?
Radium was no longer used in watches by the 1970's.
If tritium was used, only about 1/8 of it should be left now, so the night glow should be much dimmer than when new. Don't worry about the tritium, so long as you're careful with the watch. The radiation from it doesn't penetrate materials very much. Tritium becomes dangerous if eaten or inhaled, in which case the radiation can directly reach your cells.
(published on 07/08/08)
Follow-Up #2: tritium watches
You answered a question about tritims glow in the dark watch dials by saying they were no longer made. This is not true. Many companies still make tritium powered glow in the dark watches. Luminox is the most widely known, but there are many others includeing Smith and Wesson.
ACLD, Gainesville, FL
Looks like you're right about this. Radium watches are no longer made but those companies advertise tritium watches.
We'll try to find our old answer and fix it.
(republished on 07/17/06)
Follow-up on this answer.