Re: ATM Is it heat from the palms that makes the blank sieze?

["Bob May" <bobmay@nethere.com>]

Personally, I've never found any seizure due to heating or other such
problems.  All of my seizure problems have been from astigmitism (saddle
shapes) of the surface instead and the solution I found for them is to
gradually work to the peak of the problem and then insure that you rotate
the work and tool often enough.
The single long session of the fine grits is good because the mirror takes a
set for the temp you are working at and you end up making the spherical
surface with the glass at that temp.  Change the temp difference across the
glass (difference is dependent upon the room's temp and the humidity for
obvious reasons!) and the curve does change a little on the front.  This
change will make the curve open up a bit and then, when you start grinding,
that curve will close up and then the temp difference will get the mirror to
go back to the original shape and then the center will suck up causing a
hole in the middle!
I've seen people wear winter gloves to try and get rid of the heat transfer
to the glass to get rid of this problem.
Bob May
http://nav.to/bobmay
bobmay@nethere.com