A sense of atmosphere can be the difference between a so-so landscape and a masterpiece. Veteran watercolorist Donald Patterson suggests this method for creating a semblance of mist and fog in your watercolor paintings: “Make a tinted, watery mix with titanium white gouache and brush it over the watercolor background. Select areas of the mist can be darkened or removed by wetting them with water and blotting with paper towels, making the technique practically fail-safe.”
Step 1: Paint any landscape as it would appear on a clear day.
Step 2: Mix a watery wash of titanium white gouache tinted with a touch of phthalocyanine blue. On scrap paper, stroke the mix over some dried colors. Let it dry and you’ll be able to see if it has the desired coverage. If it’s too transparent, add more white. If it’s too opaque, add more color.