How to Etch Glass
An elegant mirror with a regal monogram and a laurel motif, surrounded by a gilt frame, adds polish to any entryway. The instructions below are specific to the mirror, but the technique can be adapted for any glass surface.
Source: Martha Stewart
Clean and dry the glass surface thoroughly before starting the etching process. Create the stencil: Photocopy the template or another design; for a monogram, print a letter from a computer or enlarge one on a photocopier. Center a piece of self-adhesive shelf liner on the mirror, carefully smoothing it to remove all bubbles and creases. With a pencil and ruler, draw a border around the inside edge of shelf liner; use this as a guide to center the template. Coat the template back with spray adhesive; line up the template with the border, and smooth it out over the shelf liner. With a craft knife, carefully cut out the monogram and design on the template, cutting through the shelf liner as well. As you work, peel up the cutout shelf liner and template to reveal the mirror. Press down the edges of the remaining shelf liner.
Wearing rubber gloves, use a paintbrush to fill in the stencil with a thick, even coat of etching cream, following the manufacturer's instructions. Leave it on for the recommended time. Tip: Be sure to apply a smooth, thick layer of etching cream; a thin, uneven coat will result in an inconsistent finish.
If the cream is reusable (check the label for the manufacturer's instructions), scoop it into the container; rinse mirror with a sponge or paper towels and warm water (do not reuse the sponge for other purposes). Peel back the stencil to remove.