[ATM] Silicon cement

[Mark Holm]

I would use paint thinner or perhaps better, kerosene, rather than

acetone.  The reason is that silicone resins are usually attacked more 
by low polarity hydrocarbon solvents than by moderate polarity solvents 
such as acetone.  Another advantage of kerosene is that it is a lot less 
flammable than either acetone or paint thinner.

A hunk of plywood soaked in acetone is going to be quite a flammable bit 
of material.  Paint thinner won't be a whole lot better.

Others have mentioned that, to cut through silicone bonding a mirror to 
a backing, you only need to get a flexible wire between the glass and 
backing and use it like a wire saw to slice through the silicone.  It 
could be a fairly fine wire, especially if steel or stainless steel.  
Perhaps a fine guitar string (wire) would be good or look in a hardware 
store for fine steel wire.

Mark Holm
holmmarkd at gmail.com