Bob Smith wrote:

I want to fix a mirror into a wooden frame, and have decided to use silicone
sealant.

Is it flexible enough so that the mirror won't get broken as the wood
expands and contracts?

The mirror is about 4 inches across the grain, and 10 inches with the grain,
in a pine frame.

Provided it isn't an old and valuable mirror (among other things the
silicone might affect the silvering badly) I'd think this would be
fine.

Nick