[Milsurplus] Re: [ARC5] Hot meters.. more

Scott Johnson scottjohnson1 at cox.net
Wed May 4 14:31:53 EDT 2005


Here's what I know (in general) about dial face paint:

1.  White- non-phosphorescent,designed for flood lighting in vehicles or 
aircraft

2. Green(ish) phosphorescent, needs UV stimulation to glow NOT Radioactive. 
This was used in earlier WWII aircraft and Link trainers with flourescent 
black lights.

3. yellowish-brownish- could be self-luminescent, radium or other alpha 
emitting isotope mixed with a phosphor (best checked with a scintillation 
counter that is capable of detecting alpha emission.  Alpha particles can be 
blocked with paper, so most geiger counters are rather insensitive to them. 
This paint is dangerous if ingested, but I believe it was discontinued by 
around 1944.  This paint should no be confused with plain yellowed paint 
that is often seen on aircraft istruments that have sat in the sun for 
years.

4. Sealed tritium ampules with a phosphor coating on the inside of the 
ampule-  This is used in newer compasses etc, and is much safer than the 
radium paint, because the tritium gas is sealed in the ampule, and even if 
broken, it disperses rapidly, leaving no radioactivity behind.

Probably the most potentially dangerous sustance is the radioactive paint 
applied to knobs and engraved legends on early WWII radios, it tends to 
flake off, and if ingested, is quite capable of lodging in the lung and 
starting a little tumor party.  I stay away from that stuff, and I am not 
exactly known as Mr. caution!

If anyone has serous concerns about the presence of radioactive paints, I 
will loan them my scintillation counter for the price of two-way shipping 
(or  pick up in the Phoenix area)  BTW, I have yet to find an R-390 or 
GRC-106 meter that was radioactive, all I have seen are phosphorescent.

Scott 



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