Grout Problems

Grout and Glass Mosaic Tiles: How To Avoid Disasters

Many beginners report spending hours or days gluing down tiles only to report that they all start coming off when the apply grout. Others report grout that crumbles or never being able to get all the concrete off the tiles. Here’s how to avoid ruining your mosaic:

  1. Always test your adhesive on one or two glass mosaic tiles before you spend days creating a masterpiece. You may occasionally find that the glue doesn’t bond well to the glass or the surface underneath. Simply allow the test tile to cure overnight and try prying it off in the morning. (Wear safety glasses as the tile may splinter.)
  2. Seal porous tile such as tumbled stone and unglazed ceramic tile BEFORE you grout. This prevents the grout from staining the porous surfaces. This step isn’t necessary with glass mosaic tile because smooth glass is nonporous.
  3. Allow the glue to cure for at least 24 hours before you grout.
  4. Use sanded grout if the gaps between tiles are greater than 1/8″ Grout is concrete, and it needs reinforcing the same way that concrete in roads is reinforced with gravel and iron bar. This keeps the grout from crumbling.
  5. Make sure that the surfaces of your mosaic tile are relatively level. This usually isn’t a problem with glass mosaic tile because most varieties are relatively flat. However, artistic mosaics on surfaces that aren’t flat (such as a mosaic vase) tend to have corners of tile that stick out. Be gentle with these when you apply the wet grout so that you don’t knock off any tiles. Keep in mind that wet grout may loosen water-based adhesives. Use a water-proof solvent-based adhesive if necessary. Cutting the tile into smaller pieces may also help on rounded surfaces.
  6. Mix the grout according to manufacturer instructions. Mix thoroughly. Don’t add too much water. The consistency should be a firm dough.
  7. Don’t let the grout dry out as it cures. Grout is like any other concrete. It hardens by hydration, not dehydration. After an hour, mist LIGHTLY with a spray bottle if needed. Don’t spray or drip.
  8. Grout is applied by rubbing the grout into the gaps with a spatula, trowel or rubber glove. Press the grout in thoroughly and wipe away the excess. Then make repeated passes with a damp sponge (not dripping wet). Rinse sponge and repeat as needed. This step requires more passes and more care if the surface is uneven or the gaps between the tiles are too large.
  9. Don’t erode the wet grout from the gaps between tiles. This exposes sharp edges and looks bad.
  10. The day after you grout, you may notice a residue or haze on the surface of the glass mosaic tile. Simply buff this haze away with a clean dry cloth. The last step in grouting is appropriately called “hazing.”

Mosaic Vases

Vases, votives and lamps are popular mosaic projects because they don’t require any extra work to figure out how they will be displayed or hung on the wall. However, they do require a LITTLE extra work because they are usually glass and usually rounded.

Here are some tips for grouting mosaic vases made from glass mosaic tile:

  1. If necessary, scuff the vase with sand paper to ensure that the glue bonds securely.
  2. Glue can be runny, and tiles can slide off. Simply lean the vase on the side and glue one side at time.
  3. Cut the tile small enough so that the flat tile can fit to the rounded vase.
  4. Make sure the glue cures for 48 hours or more before grouting.
  5. Grout gently.