The ease of mixing color is one of the things I like most about watercolor paint. With oil or acrylic paint, you need a palette knife and a lot of paint. With watercolor, you only need a little paint and a lot of water.
Watercolor painting is all about the ratio of water to paint. The consistency of mixed watercolor paint can run from a pale tea puddle to a thicker mix like heavy cream. The more water added and the thinner the consistency of the paint, the lighter the painted result on the paper.
Here are the basic technical steps to mixing color with watercolor paint:
Now, to be clear, this is not the only way to mix watercolor paint. You could thin the first color and brush it onto the paper, then add the second thinned color right to the paper. Some artists will just dab in colors to wet paper to get cool and unexpected effects, like in the picture above. You can also use a glazing technique of thin layers of wet color over dry paint on the paper to get to your desired result.
Above, I mention cleaning your brush frequently. Why is that important? Let’s say you start mixing colors using new dabs of paint right out of the tubes. If you plan to use that new paint mixture to go on as a thin layer of color, you’ll need to add lots of water as mentioned.
Once you mix the various paint colors well and the result is the consistency that you want, the best thing to do is clean your brush in clear water and dab it dry with a towel. Now you can go back to your mixed paint puddle and just pick up a little paint and start painting on your paper. If you were to go straight to the paper after mixing, and not clean your brush, I guarantee there would be little bits of undiluted paint that would make dark streaks in your light wash.
Although other artists might disagree, I think if you have a palette of dry paint set up, it’s best not to contaminate the clean wells of paint with other colors. The solution is to clean your brush once you have a puddle of a single color, and then move on to the second color.