Tritium Technology in Military Watches
by Trevor Rowell
Copyright 2006 Trevor Rowell
Tritium paint has been used on the hands and numerals of watches since the
1930s. At first this technology was Top Secret and restricted to use on
military watches.
Tritium paint on watches is a mixture of tritium and phospor. Tritium is
naturally radio-active and needs no external source of light or charge to
work. Tritium does not glow. As it decays, tritium emits beta radiation, which
are a group of excited electrons that in turn excite the electron in the
phosphor atoms making them emit photons, or light. As they return to their
ground (non-excited) state, the phosphor glows. Phosphor can also be excited
by UV light from the sun or other light sources. Thus, the tritium paint
relies on tritium radioactivity to make the phosphor glow in the dark, not any
charge from external light source.
Tritium, has a half life of 12.3 years, a half-life is simply the time it
takes HALF of the tritium to decay. So as long as there is enough tritium in
the paint, the watch will glow for years.
Due to the toxicity of tritium based paint, a new technology was developed by
mb-microtec in Switzerland. This uses tritium gas sealed in vials. The
principle is the same but the tritium gas causes the coating on the vial to
glow. The levels of radiation are so small that they pose no risk to the
wearer. This technology has been used in the Traser H3, Luminox and Marathon
military watches. In recent years SRB of Canada have developed a similar
system, this is used by manufacturers such as Smith and Wesson, Rescuer and
NITE. SRB tritium is not as yet as well developed as the mb-microtec
technology, only offering around 80 - 90% of the luminescence.
The main advantage of tritium in military watches is that there is no
additional drain on the watch battery to power the night light source, however
these watches do have a drawback in that they can be picked up at great
distance by night vision equipment. It is therefore important that these
watches are covered during military operations at night.
As the technology has become cheaper it is finding its way into the civillian
market. Many sportsmen such as anglers and shooters wear tritium based watches
with Luminox and Traser being the most popular.
Each year more and more manufacturers are bringing new tritium watches onto
the market. As the tritium light sources from SRB become more popular and
combined with cheaper production in China, it wont be long before we see
tritium used in purely civillian watches.
Trevor Rowell served for 16 years in the British Army and is currently
involved in the development of new technology for military and police
applications. The military watches mentioned in this article are available
from http://www.telford-services.com
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