Mosaic grout is used to fill in the spaces left between the tesserae, which are the small pieces of glass and stone used to make the mosaic. Grouting keeps the mosaic clean, improves the overall design, and holds the mosaic together.
Choosing the Right Grout
When it comes to choosing grout, the rule of thumb is to use sanded grout for spaces wider than 1/8 of an inch, and unsanded grout otherwise. You can buy either ready-made grout or grout powder. Grout is available in many colors, so pick the one that is most suited to your design and color scheme. Light colors are preferably avoided when making floor tiles. You can also make your own color by acrylic paints to your grout mix.
Mixing the Grout
Mix the grout powder in a bucket, following the directions on the label. Add some Weldbond glue to this mix to improve the adhesive properties of your grout. To check consistency, use a mixing stick or spatula to scoop up a bit of the mixture. Next, turn over the spatula/mixing stick, if it drips, it needs more grout powder, and if it begins to crumble, it needs more water. You know you have the right consistency when the mix sticks to the spatula/mixing stick. If you are making your own color, this is the time when you add color to the mixture. It is always better to make more grout mix than needed.
Prepare Your Workspace
If you are working inside, line the floor with newspapers. Also, before you begin applying the grout, keep the grout float, grout sponge, and a bucket of water handy.
Applying the Grout
Apply the grout mix onto the mosaic, using the grout float. You can also use your hands (gloved) if you are more comfortable without the float. Push the grout into all the spaces between the tesserae and the joints. Use the grout to cover up any exposed edges. While applying grout, remove the excess grout as well. Make sure to check from all angles before you consider the application finished. Next, let the grout set for at least five minutes. You can always check for readiness by moving your hand over the tile. If it smears, it needs to dry more. If it powders, it is ready to be sponged.
Wipe Off the Excess Grout
Use the grout sponge to wipe the tile and clean off the excess. Keep the sponge wet by dipping it in the bucket of water, albeit squeeze out all excess water before applying the sponge to the tile. Once you have wiped the entire area, there will be a slight haze left on the surface. Let it sit for five minutes and then buff with a dry lint-free cloth.
Apply the Sealant
To ensure that your mosaic retains its color and shine, apply a sealant after the grout has completely dried, approximately after 48 hours. Apply the sealant using a brush according to the label instructions.