Pinching, not just for ol' men

I finally caught on to why I was seeing a slight double after I glued my mirror to the sell with silicon. Three dabs on the cell and on the three posts sticking up beside the edge of the mirror. The mirror is very thin, easily less than an inch and 13.1 inch diameter (vintage coulter).

I glue at room temperature and take it outside to cool down, thus the mirror tries to deform slightly based on temperature change but is pinched in the process. I'm starting to believe that glueing the back to the cell is ok, but glueing to the posts is probably a problem.

Does this sound right?

also, is plop in inches or metric?

David Roberts :S

I would agree that the glue on the back was OK but on the sides was not good.
But more than that, I think that 3 points on a 13.1" thin mirror is inadequate and that you need to reconsider the cell type to get proper support.