Unlike other mirrors in a house, a bathroom mirror is usually frameless. Frameless mirrors are more difficult to mount because they do not come with hooks for other hanging apparatus. The larger the mirror, the more difficult it is to hang. Follow these steps to glue a mirror to your bathroom wall and make sure it is level without making a mess.
Step 1 - Be Sure of the Location
Before you apply glue to your mirror, be sure that it will fit. Once the glue has dried and hardened, moving the mirror to another location will likely strip not only the wall's paint, but also the drywall's paper surface.
Step 2 - Mark the Mirror's Location on the Wall
Place a board against the wall just below the spot where you plan to glue your mirror. If possible, the board should be long enough that its top edge will support the mirror when it's in position on the wall. To hold the board in place, place several strips of masking tape across the board with the tape ends stuck to the wall. Place the lower edge of the mirror on the board at a location you've chosen for the mirror. Have someone hold the mirror in place while you check it with a level.
Step 3 - Apply Glue to the Mirror
Apply the glue on the mirror back at least 1 inch in from the mirror's outer edge. Run a bead of glue all the way around the mirror, along with several beads in its middle. That should be enough glue to hold the mirror to the wall.
Step 4 - Fix the Mirror to the Wall
Hold the mirror in place just over the pencil lines you made on the wall. When the mirror is in place with the penciled lines inside the edges of the mirror and the bottom mirror edge low enough that it will rest on the board, press the mirror against the wall with its bottom edge resting over the top edge of the board.
Step 5 - Wait for the Glue to Dry
Use masking tape strips to hold the mirror in place while it dries. After 24 hours, the glue should be set. You can then remove the board and the masking tape strips.