If you are looking to mount your mirrored surface with a glue or adhesive, we suggest that you first back your mirror as follows:
First, apply 2 coats of Copper Tite Vehicle #3 to the silver layer, let dry 1 hour.
Then, apply 3 coats 0f #390 backing paint, let dry 2-4 hours between coats and 24 hours before shellac.
Finally, apply 1 coat of shellac paint to seal.
After you have finished the suggested backing protocol, apply no more than a dime sized blob of mirror mastic (we suggest Palmer or Gunther) for every square foot of mirrored substrate. You should aim to have some kind of support rail on the bottom of the mirror so that there isn't too much shearing stress on the paint (which could cause the backing to detach).