A simple, secure way to mount an unbacked, unframed mirror on a wall or door is with J-shaped mirror clips on the bottom and Z-shaped clips along the top and sides.
The number and size of clips needed depend upon the size and weight of the mirror. Ask the advice of a glass dealer or a hardware dealer that carries the clips.
First draw a level guideline on which to position the base clips. Secure 2 or 3 J-clips along the pencil line, using hollow-wall fasteners, toggles, or wall anchors if necessary. These clips will support most of the minor’s weight, so be sure they are securely anchored.
If the clips are unpadded, add thin adhesive-backed felt to prevent the minor’s being scratched. With a helper, gently lower the mirror into position. While your helper holds the mirror, install Z-clips at regular intervals around the sides and top so that the mirror hugs the wall.
As an alternative, have the glass dealer drill holes through the corners of the mirror. Mount the mirror with long screws sunk in preset wall an-chors; cover the screwheads with decorative rosettes.