Glass Mosaic Tile Art – Tesserae Size and Texture

Making wonderful glass mosaic tile art is easy! Let me show you how. I've found that tesserae size is nearly as important as andamento in creating the desired look and feel of a mosaic. For example, a background done in 1/4-inch opus regulatum looks and feels entirely different than the same pattern done with 3/4-inch tesserae. Typical tesserae sizes are: 3/4-inch x 3/4-inch (eg, square vitreous glass tile); 3/4-inch x 3/8-inch (eg, rectangular smalti); 3/8-inch x 3/8-inch (eg, manufactured 3/8-inch square vitreous glass tile or 3/4-inch vitreous squares hand cut into four equal sized squares); 3/16-inch x 3/16-inch or less (ie, for projects known as "micro mosaic"); free-form shapes in varying sizes cut from sheets of stained glass.

When using squares less than 3/4-inch, I prefer to hand cut them. The resulting irregular sides enhance the feel of the grout lines. Because the hand-cut tesserae have irregular lines, the grout lines are also irregular instead of the precise lines you get when using manufactured vitreous tiles.

Try using stained glass for large pieces of tessera when creating your focal points. For example, suppose your primary focal point is a sunflower 6-inches diameter (including the petals). You could make the 4-inch diameter head using a single piece of stained glass, the individual petals using 1-inch oblong pieces, and individual leaves using 3-inch pieces. Then, when all focal points are in place, complete the mosaic with a background done in vitreous tiles hand cut to 3/8-inch squares in opus regulatum.

As with many things in life, size matters, so put some thought into the tesserae size for focal points, backgrounds, and borders.

Different tessera thicknesses catch and reflect light producing beautiful effects. Create texture and depth by combining different types of tesserae, such as smalti, vitreous glass, marbles, and stones. However, ensure texture works for your piece. For example, if you're doing a tabletop, the surface must be flat so tesserae of varying thicknesses will not work.

Be careful, because it's not easy getting the right combination of tessera types and thicknesses. In the wrong light, varying thicknesses cast shadows that can ruin the mosaic's look. Planning is important. Before choosing your tessera types and thicknesses, think about where you'll display your mosaic and the ambient light conditions. Will it be displayed in direct sunlight or in a dark hallway? Will the light source be directly overhead or from the side or bottom?

The main reason I'm not keen on incorporating texture into my mosaics is that grouting is a challenge. Grout spacing is critical when creating texture with tesserae. The grout must have enough room to naturally slope from the higher tesserae to the lower tesserae. Otherwise, the grout job can look dreadfully sloppy.

With proper planning, patience, and attention to detail when grouting, results from incorporating texture can be wonderful. Without them, results can be disastrous.

Remember, making mosaic art is easy. You can do it. Yes, you can!