"coffelt2" wrote in
:

Old 660 had a thorium alloy panel on top of left wing which
had a radioactive icon painted on it, and a note in the
"Form 1" to not work around it for longer than (???)
minutes.
Anyone know what that was all about? Mr.
"Motor Mouth", the civilian crew-chief at Edwards AFB, told me once,
but can't remember anymore.

Old Chief Lynn

From some of the papers I found, I would suspect that it was a test
panel to measure the corrosion resistance of a magnesium / Thorium alloy
skin for high-speed aircraft with coatings

Found several reports on tests by Convair dated 1957-1959 & 1962

"Dow #17 treatment applied to HK-31 magnesium-thorium alloy*
protects the surface of the alloy against corrosion and at the
same time offers a potentially good surface for adhesive bonding.
Therefore, the purpose of this test request was to obtain
information applicable to the adhesive bonding of Dow #17
treated HK-31 magnesium-thorium alloy"


"I. Effect of Certain Process Variables on Dow #17 Treated
HK-31 Magnesium-Thorium Bonded With AF-31 Adhesive"


"II. Lap Shear Strength of Standard Dow #17 Treated Magnesium
Thorium Alloy - Primed With EC-1459 and Bonded with
AF-31 Adhesive "



also a test report of a magnesium / Thorium alloy skin on a F9F


and since Thorium is naturally radioactive , the warning.symbol...