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Gary wrote-


|  Or maybe one can just buy new radium paint. This auction just ended.
|
| http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350376559549

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No, Gary. That won't be Radium paint, and wasn't advertised as such; just
as non-toxic luminous paint, which is the sort of stuff described by Bill
Morris, that needs activating first by shining a light on it. I doubt if
Radium paint is available anywhere, in any form, anymore.

The only truly luminous self-illumination that I know of, available at
present, is powered by the low-energy beta-particles emitted by the
radioactive gas Tritium (an isotope of Hydrogen, and a fuel component of
the Hydrogen bomb). This has been used in emergency-illumination of warning
signs in aircraft and elsewhere, and maybe still is.

Usually the Tritium is contained in a sealed glass capsule, with luminous
material painted on the inside. I have nice hand bearing-compasses,
initially from France, labelled Opti-compass or Minicompas, of hockey-puck
form, that were lit this way.  Similar compasses, with what looks like the
same type of illumination, are still available under the French label Vion.

Unfortunately, Tritium has a half-life of about 15 years, so the light
inevitably fades. Whether the luminous material loses its magic property as
well, I don't know, but the illumination of these old compasses, combined
with my dimming old eyes, is no longer useful to me, and I've replaced one
with a light-emitting diode (LED) and battery (and a resistor to limit the
current) , which works well. The snag is that I haven't (yet) been able to
find a non-magnetic 3-volt battery, so the end-result has to be bigger
assembly just to get the battery away to a safe distance. If anyone has a
solution to that , it would be welcomed.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

   

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