Q: How do I prevent the mesh backing on transparent glass mosaic tile from showing through when the tile is installed?

A: Tom Meehan, a second-generation tile installer and co-author of Working with Tile who lives and works in Harwich, Mass., responds: Glass tile can be very frustrating, even when you do things right. Most problems with glass tile arise from installation methods. My article, “Working With Glass Tile” (Mar/17), goes into more detail about the whole installation process.

Proper installation of any glass tile begins with prepping the walls. For installations in bathrooms and other high-moisture areas, I usually give the walls a coat of liquid stress-crack membrane. I follow that application with a skim coat of the thinset recommended by the manufacturer of the glass tile that I will be installing. When the skim coat has set, I give it a light sanding to make sure there are no ridges or bumps.

Mesh backing lets you install the tiny glass tiles as a single sheet (1). Start by spreading a thin, even layer of thinset on the wall. Comb the thinset in one direction using a notched trowel with the recommended-size teeth.
Mesh backing lets you install the tiny glass tiles as a single sheet (1). Start by spreading a thin, even layer of thinset on the wall. Comb the thinset in one direction using a notched trowel with the recommended-size teeth.

Because the thinset will be visible through the glass tile, it’s important to use white thinset and to make sure you’re using the thinset recommended by the glass-tile manufacturer. It is equally important that you have 100% coverage of the thinset—especially with mesh-backed glass tile.

Next, flatten the ridges with the flat side of the trowel.
Next, flatten the ridges with the flat side of the trowel.

To achieve 100% coverage, spread the thinset on the wall with the flat side of the trowel, as close to perfectly smooth as possible. Then switch to the notched side of the trowel (use the appropriate-size teeth for the size of the tile) and comb the thinset evenly in one direction. Last, go back to the flat side of the trowel and flatten all of the ridges of the thinset without scraping off any of the thinset, while continuing to maintain an even thickness.

Then press the tile into the thinset and move it side to side slightly for 100% coverage.
Then press the tile into the thinset and move it side to side slightly for 100% coverage.

When the thinset is ready, push the sheet of glass tile into it, shifting the tile back and forth until it is 100% embedded in the thinset (3). The white mesh on the back of the sheet should disappear completely into the thinset. Occasionally, some threads of the mesh might be visible next to the grout joints, but only if you are looking at the tile at an angle. When in doubt, try out your installation methods on a small area first.