[ATM] Silicone Failure

[Jay Kirkland <jaykirk2@compusmart.ab.ca>]

Nearing the end of the re-build of my 20", which seems to be taking 
forever, tho I'm working on it fairly constantly. I was going to try 
mounting the mirror onto its support points on the cell using silicone. 
Siliconed the mirror onto its cell about two weeks ago and let it cure. 
The support points are lightly sanded 1" diameter elevator bolts. I used 
a 1" diameter 1/8" thick blob of silicone at each of the 27 points 
(overkill, I know, but I was paranoid about not using any other form of 
mirror support). I used GE Silicone II, supposedly their strongest for 
metals and glass. It stuck to the glass just fine. As soon as the mirror 
neared verical, the top 18 support points sheared away from the metal. 
At least the lower 9 held the mirror in place while I got it back onto 
its back. Give a cheer for paranoia! But what did I do wrong? Wrong 
silicone?
    Additional question, thought of today as I was installing the mirror 
cell: what will -30 C/F temperatures do to the strength/flexibility of 
silicone? It's not an uncommon temp here. (I used to laugh at the idea 
of  cold cameras, just leave a regular camera out for a few hours here 
and you end up with the same effect.)
    Jay

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