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Installing Glass Mosaic Tiles

posted Feb 3, 2012, 8:51 AM by Michael Dekker   [ updated Mar 16, 2012, 6:15 AM ]
Mosaic tiles taped to prevent slipping
Since my troubles with the glass tiles the first day, I wanted to postpone my pain as long as I could, and simply installed support bars to help me with all the upper rows, leaving a gap for my glass tiles to be installed later. But now I had to tackle it. So I applied mortar to the band on the wall, back-buttered the glass tiles with a thin layer, laid the tiles on the wall, and used green tape to hold the tiles at the correct level. A trick I used is to use a thin wedge on the bottom of the tiles to hold the tiles at the correct height. Once the tiles had 1/2 set (in a couple of hours) I returned and carefully removed the wedge so that it would not set permanently. Well, I learned a couple of lessons from this. First is that tape has trouble sticking to glass tile when it is not perfectly clean, and sticks even less on the large tiles because of the small amount of dust remaining from the tile cutting. My second lesson is that adjusting the depth of the glass tiles is virtually impossible to do with your hands. After much fiddling and frustration, I got to a point that I found "acceptable" and left it alone. The individual mosaic tiles were not all "flat" with respect to each other, but it was the best I felt I could do. No more glass tile for that day, and I went on to other tasks feeling frustrated.

Mosaic tiles in the process of being installed - checking for evenness
When I had advanced enough elsewhere and had let a day or so pass, I finally returned to the glass tiles with some new ideas and strategies, and I am glad to say that they worked! As you can see from the image at the right, the resulting glass tiles are smooth, flat, and the gaps between them are very clean. How did I accomplish this? What was my trick?

  • Clean the surface of the glass tile (Windex for me)
  • Clean the wall tiles above the glass tiles (again, Windex)
  • Apply mortar to the band where I want the glass tiles to be, to a thickness that will leave the tiles at the same depth as the surrounding tiles. Do NOT use the notched side of the trowel. Make this layer of mortar perfectly flat and smooth. The smoother you can get this, the happier you will be with the result
  • Optionally, insert a thin support  on the tiles below your glass blocks. I needed to do this because my gap was slightly oversized, and I needed something to keep my sheet of tiles supported slightly. You could probably get away without this, but I found it very useful. The "tombstone" spacers make a mess of things on the small glass tiles, since you would need one under every column.
  • Lay your glass tile face-down on a square of stiff cardboard that is approximately the same dimensions as your sheet of glass tiles, and carefully butter the back of the blocks with mortar. Be extremely gentle to not squeeze the mortar between the tiles. Do not use the notched side of the trowel, use the flat side instead. I used a 4" putty knife myself.
  • Last section of glass tiles taped  for support
    Get 4-5 strips of green tape ready by temporarily sticking it to the tiles above the band where the glass tiles will be placed.
  • Clean your hands with a cloth since any moist mortar on your hands will make a mess in the coming steps.
  • Lift the cardboard holding your mosaic tiles, and carefully shift the tiles so the bottom of the mosaic sheet is at the edge of your cardboard
  • Place the cardboard, still holding it horizontal, so that the bottom of the mosaic sheet is against the spacer, then raise the cardboard so that it becomes vertical, pressing gently against the mosaic sheet so that it presses against the mortar bed that you laid.
  • Finished shot of the glass mosaic tiles in the tub/shower area
    Carefully use the cardboard sheet to "massage" the mosaic sheet into place, using small circular motions (1/4" or less). Avoid the temptation to press hard, since all that will do is squeeze an excess of mortar between the glass blocks that you will later have to clean out. Once you think it will hold its own weight, you can remove the cardboard then carefully (and very gently) tape the glass blocks to the tiles above it. This will keep the tiles from sagging, or that is what I told myself anyway.
  • Worked like a charm.
Lots of work, lots of time, and just remember that your mortar is only good for a couple of hours before it should not be used! Make small batches, and keep it mixed.

Before you apply the grout, make sure you clean up between the tiles, since you don't want to see any mortar after the grout is applied. A carbide-tipped scraping tool is perfect for this, such as the one sold for scoring-and-cutting cement backer boards.

The floor was next, so stay tuned!
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