How to Grout and Seal a Mosaic

Grouting is the step that makes a mosaic look finished. It fills the gaps between tiles, locks everything in place, and ties the colors together. It can feel messy at first, but it's very doable with a little prep. If you're new to mosaics, start with Mosaic Tiles 101.

Before you grout

Make sure your tiles are firmly attached. Let your adhesive cure fully, often 24 hours or longer, following the product label. Browse our adhesives and mosaic tools and supplies. For projects used outdoors or in wet areas, use adhesive and grout rated for that use.

Choose your grout

• Unsanded grout: Smooth, best for narrow gaps (about 1/8 inch or less) and for delicate surfaces like glass, which sand can scratch.
• Sanded grout: Better for wider gaps because the sand reduces shrinking and cracking.

Check the grout label for recommended joint widths and any restrictions with glass tile.

Mix the grout

Wear gloves and a dust mask. Follow the package directions and add water slowly, stirring until the mixture is thick like peanut butter. Let it rest a few minutes, then stir again. Mix only what you can use before it starts to set.

Apply the grout

1. Spread grout over the surface with a rubber float or a gloved hand, pressing it into every gap.
2. Work in small sections so the grout doesn't dry before you wipe it.
3. Scrape off the excess at a diagonal so you don't pull grout out of the joints.

Clean up

After about 10 to 15 minutes, wipe the tiles with a barely damp sponge in gentle circles. Rinse the sponge often and wring it well. Too much water weakens the grout. A hazy film will remain; after it dries, buff it off with a soft dry cloth. Repeat if needed.

Let it cure

Let the grout cure for the time on the label, usually a couple of days, before sealing or heavy use.

Seal it

Grout is porous and stains easily. Apply a grout or tile sealer according to the label to protect it, especially for projects used outdoors or around water. Some porous tiles and surfaces also benefit from sealing. Seal only after the grout has fully cured.

Tips

• Test your grout color on a small area or a scrap first, since it looks darker wet.
• Use a soft sponge so you don't scratch delicate tile (see our sponges).
• Wear gloves, since grout can irritate skin.

Shop mosaic tiles and mosaic surfaces to start your next project.