Mosaic Materials and Methods

© 2013 Silva Hayes


For indoor projects, use wood, terracotta, glass, etc., almost anything except flexible plastic. The substrate must be rigid. If it flexes, the grout will crack.

For outdoors, do NOT use wood. Wood will eventually warp no matter how well it is sealed. Use hardibacker, wedi board, cement backer board, glass, or concrete. Some terracotta will hold up well for years, and other terracotta will not; this might be due to different clays and firing methods.


Ceramic tile, vitreous glass tile, stained glass, smalti, broken china and pottery, glass beads, shells, pebbles, and jewelry. Avoid wooden beads and organic beads such as those made from beans or pods UNLESS they are well sealed.


For indoor projects, use MAC glue or Weldbond water-based glue (except for mirror tiles). Do not use Weldbond for outdoor projects. When wet, Weldbond reverts to its liquid state.

For mirror tiles, use GE Silicone II Kitchen and Bath clear sealant.

For outdoor projects use Mapei brand Ultra Flex 2 polymer modified mortar (this is a thinset to be used as an adhesive). I have also used the GE Silicone II on outdoor projects and so far (5 years) it is holding up well.

For glass on glass, use MAC Glue, available online (Maryland Mosaics) and locally in Austin at Blue Moon Glassworks.


Polyblend sanded grout mixed with water, or other sanded grout that does not contain a polyblend mixed with Acrylic Mortar Admix instead of water. I do not recommend unsanded grout or premixed grout.


For indoor projects, use Aqua Mix Grout Sealer. Brush on, polish off the tesserae.

For outdoor projects, use Aqua Mix UltraSeal Premium Stone and Tile Sealer. Spray on, polish off the tesserae.  (I pour some into a spray bottle, spray, then pour back into the original container and was the spray bottle well.)  Another good one is DuPont Grout Sealer for indoor and outdoor use.

Basic Mosaic Steps to follow:

1. Glue on tesserae. Wait 24 hours or longer.

2. Grout. Clean tesserae. Wait 24 hours or longer.

3. Seal. Clean and polish tesserae.


Tile nippers. The best are the wheeled Leponitt nippers.

Carborundum stone. This may be called a kitchen sharpener. Look for one with a handle. Used to take the sharp edge off of glass or broken plates.

Sponges, rectangular, to wipe the grout off the tesserae.

Old terry cloth rags, craft sticks, plastic bins for mixing grout and a bucket for water.


Blue painter’s tape


Direct – glue tesserae directly onto the substrate. Tesserae can also be glued to mesh and then transported elsewhere and affixed, to a wall or a fireplace surround, for example.

Indirect – lay tesserae upside down in a mold coated with Vaseline or mold release, and pour cement, as for a stepping stone, or glue tesserae upside down onto brown Kraft paper. The indirect method is usually used when a smooth surface is required, or when mosaics are made in a studio and then transported elsewhere for installation. The tesserae MUST be flat and secure, else the cement can creep under it and spoil the look.

A helpful book is Classic Mosaic by Elaine M. Goodwin.

On my blog: on the right there are some links for helpful instructions on nipping plates and how to order MAC glue and mesh.


After gluing, wait 24 hours and then grout. Selecting a color is extremely important. My favorite color is a soft pale brown. Another favorite is black. Least favorite is white. Try shaking some dry grout onto your piece and into the grout lines to see if the color works for you.

Mix the grout with water or admix or a mixture of both. Mix in a disposable container. Do not breathe in the dust. Mix to a consistency of peanut butter. Wait up to ten minutes (this is called slaking) and then spread with a tool or popsicle stick, or with your gloved hand. Make sure the grout fills in every nook and cranny.

Wait only a moment or two and then gently begin to remove the grout from the tesserae. At first use your gloved fingers. Then a dry paper towel. After removing the excess, gently pass over the mosaic with a damp sponge (not a dripping wet sponge). Your goal is to remove all the grout from the surface of the tesserae but you do not want to dish out the grout lines; you want them to remain smooth and level with the edges of the tesserae. At this point, you can pat the grout with a sponge or your finger and you can smooth a problem area with a wet makeup brush.

Allow the grout to firm up (about 30 minutes) and then carefully wipe the haze off the tesserae. When you are certain that the grout won’t be disturbed, you can firmly polish the mosaic with a wet washcloth, wrung out well.


Allow to sit undisturbed for 24 hours, then seal. The sealer has the consistency of water. Apply all over the piece, making sure that the edges are well sealed. Immediately polish the sealer off the tesserae.