Ben Abzug wrote:
Hi, I recently purchased a Mach Meter with the intention of partially
disassembling it and installing the front portion of the gauge in my
truck. (bit of an aviation nut?). Anyway, it donned on my that the
gauge face may have been screened in Radium paint. How can I find out
if this is the case with out access to a Geiger counter? Normally the
small amount of radiation from Radium watches and the like doesn't
worry me too much, but since I'll being taking it apart...

It's a Kollsman made A-2B Machmeter with a range from Mach .5 to 1.5.
On a hunch I'd say that it was manufactured in the mid 50s to the early
60s, though there's no date stamp on it that I can find. Does anyone
know when the Air Force stopped using radium instruments?

The paint has an off white appearance and seems slightly thick,
especially on the needle. While it doesn't glow, I've read that the
radium used on watch faces (an I assume instrument faces as well) can
"burn" out the phosphorescent mixture in the paint leaving a non
glowing, but still radioactive coating.

Radium paint that is old is usually a brownish green color. It will
burn the underside of the altimiter's crystal with a replica of the
numbers... and it won't glow under a blacklight

You could place a pack of poloroid film on the face over night, and
shoot off the sheets with your hand over the lense. If it is radium,
there will be a neat image of the dial on each sheet.

Or, if you are in the Washington area, I'll loan you a counter.

-Chuck