Some color problems in mosaic are sneaky and not about making a single bad decision. Sometimes it just happens after a few pieces have been laid, and a patch that had seemed lively in your hand becomes muddy when it hits the surface, or a strong contrast that had seemed interesting now seems jarring. The novice often blames lack of materials, but most color issues in mosaic are issues of arrangement. Color in mosaic isn’t just about beautiful pieces; it’s about how beautiful pieces relate when they adjoin each other and are separated by grout, texture, and lighting.
A great exercise for learning to work in color in mosaic is to forget about designing something for a while and just make little color patches. Choose three tile colors that are relatively close to one another and lay a small square patch no bigger than the palm of your hand. Then lay a second patch using those same three colors but add a fourth color that contrasts sharply with them. Place the two patches side by side and step back from them. It shouldn’t take long to see the difference. One should appear more serene or cohesive, while the other might seem to vibrate or seem discordant. This simple exercise can teach you that color is relative: one tile can change the character of an entire patch.
One of the most common errors in mosaic color is to select tile colors that are all beautiful but also similar in value, which means that they are roughly equivalent in terms of lightness or darkness. When that happens, the design can lack definition, even if the colors are otherwise different. A dark green and a dark blue might not provide as much contrast as you expect once grout is factored in. The solution is to always consider value before you lay a tile. You can do this by squinting at the tiles or by looking at them in a softer light. If they don’t appear nearly the same, you might need to separate them with a lighter color or a darker accent or a more defined pattern. Another common mistake is to scatter strong accent colors all over a piece more or less evenly. This can make the whole piece feel agitated. Strong color usually works better when it has a purpose and isn’t competing with itself from every direction.
If you aren’t sure what to do, reduce the number of colors instead of expanding it. The typical novice solution to a color problem is to keep adding colors and hope that the right one will somehow magically fix the problem. More often than not, it just makes things worse. Work with a smaller number of colors and try to discern the nuances of that smaller range. A more-restricted palette can make a mosaic more coherent and can help you see where you need contrast. You can also test how colors play together without committing them to adhesive by laying out a small patch and taking a digital photo of it. Sometimes you can see problematic areas when you look at a design on a computer screen that you can’t see when you are bent over a worktable.
You can hone your ability to judge color and contrast with a simple 15-minute exercise that requires very little material. Spend the first five minutes laying a small patch made from three tile colors that are relatively close to one another. Then spend the next five minutes laying a few accent tiles with higher contrast, and observe how they change the overall character of the patch. Use the last five minutes to remove the accent tiles and see if the patch appears more unified or merely less interesting. That comparison can teach you more about how to work in color than any set of rules because it teaches your eye based on empirical evidence.
As you gain more experience working in color, you will begin to trust restraint. Not every area of a mosaic needs to pop with contrast, and not every tile that you love has to go into every mosaic. Mosaic color is more effective when every decision serves the larger surface and not merely itself. With enough time and practice, you will start to see when an area needs continuity and calmness and when it needs a rest and when one well-placed accent tile can define an entire area. You develop that ability through observation and revision and a willingness to reconsider before you have committed to too many decisions that no longer inspire you.