When it comes time to install you glass tiles, here are some hints gathered from the pros:
- Prepare the substrate. There should be no cracks or voids, lumps or uneven surfaces. Fix defects first, otherwise there is a strong chance that they may show up later and spoil your renovation. Use a proper leveling compound for the substrate you are working on. Do not use thinset to level uneven surfaces because it will shrink and crack as it dries.
- Apply a crack suppression membrane. It is also very useful to waterproof wet areas first, and a crack suppression membrane can often accomplish both in one shot. Avoid very colorful membranes or waterproofing compounds as the color can bleed through to the surface of the tile. We are fond of the "Peel & Stick" style of membrane like Mapegard 2 by Mapei or Laticrete Fracture Ban.
- Apply tile only after you have carefully mapped out where every tile will be placed. Start by placing an array of 3 tiles by 3 tiles on a level surface, using 1/16" tile spacers to assist in the layout. Measure the length and width of the array. Now transfer this measurement to create a grid on the entire area to be tiled. Be sure to use a long level to keep everything straight. Only after you have satisfied yourself and you know where every tile will be placed, then move onto the next step.
- Only use a 2-part polymer modified white thinset for setting your glass tiles. Organic mastics (non-cementitious glues) are not suitable because they will trap moisture behind the tile that will discolor over time. We are fond of Mapei's white Granirapid for setting glass tiles.
- Mix only as much thinset as can be used in 20 minutes. Follow the manufacturer's mixing instructions carefully. Apply thinset with a 3/16" V notched trowel and then use the flat side of the trowel to strike down the notches before applying tile, being careful not to remove thinset in the process. It is good practice to "Back-Butter" the back of the tile to increase adhesion and help hide any thinset notches. Note: this is one of the most common installations failures. If there are thinset ridges still showing under the glass, they will become visible after the thinset dries.
- The second most common failure we hear is when thinset is applied thick, specially to overcome substrate flaws (see note number 1 above). Thinset is designed to be applied very thin, and it will shrink and crack as it dries. There is enough force in the shrinking process to break the glass over time (typically within 6 months of the installation) so avoid this disappointment and level your substrate first.
- Cutting glass tiles is not difficult if one uses the right tools. The most common tool is a "wet" saw that uses a specially formulated diamond blade to cut away the glass. Wet saws can be rented or purchased, but they typically come with a general purpose blade built with coarse diamonds that will chip glass and remove the ceramic coating. The third most common complaint we hear refers to the chipping caused by bad blades. Montolit make a glass specific blade called Cermont CPV that cuts tile like butter.
- After 24 hours, the tile can be grouted. Generally you need to avoid coarse, sharp sand used as a filler in the cementitious grout, so we recommend "unsanded" grout to prevent scratching of the tile surface. We are fond of Bostik Dimension Rapidcure urethane grouts that incorporporate glass beads to add sparkle to the installation. These grouts are stain resistant and do not require sealers, but be very careful to clean any residue right away otherwise you will be stuck with scrubbing it off later.