On Tue, 14 Feb 2006 23:57:44 GMT, Martin Robiette
wrote:

Now that sounds like a good Plan B - never thought of silicone.

If you apply silicone to a metallised mirror then you'll etch through
the silvering. "Bathroom grade" mirrors have a plastic coating that
avoids this, and these days almost all mirrors are coated like this.
Easier though is to use a non-acidic mastic that's sold as suitable for
mirrors - Screwfix do one.