First you must understand how to break down your compositions into values, then you must translate value to color in watercolor painting.
Watercolor artist Michael Reardon takes the mystery out of seeing values in your subject in the October 2016 issue of Watercolor Artist.
Values are a range of tones that span from pure white to pure black.On a scale of 1 to 10, white has a value of 1, while black has a 10. Values 1 to 3 are considered light. Values 4 to 7 are mid-range. Values 7 to 10 are dark.
In watercolor painting, the water-to-paint ratio creates the value range. The more water added to the paint, the lighter the value. Conversely, the more paint in the mixture, the darker the value.
I use a set of dairy analogies to determine the ratio of paint to water I need for each value. For the lightest values, I think of non-fat milk (1-2) or a 2-percent milk consistency (3-4). For the medium to dark values, I imagine whole milk (5-6), cream (7-8) or yogurt (9-10) consistency mixtures.
The Value of Color
None of the primary hues possess the full value range of 1-10. Yellow, for example, rarely gets beyond a 3 in value. Reds and blues have a greater range, but never get to 10 on their own. They must be mixed to reach a true black. Generally the staining colors have the greatest range. For example, I make black by mixing Phthalo Green and Carmine. Cobalt Blue is strictly a mid-range hue. No matter which colors are mixed with it, it will never get very dark. It is very important to understand which colors have large value ranges, and which don’t. Since watercolors dry so much lighter than when wet, it is very common to think you have painted a rich dark color when in fact it’s a mid-range value when it dries. Here are some tips for how to translate value to color in watercolor painting.
Bismuth Vanadate Yellow
All yellows have a limited value range, from 2 to 5. Bismuth Vanadate Yellow, a relatively strong yellow, reaches a value of 3 at full strength. Some yellows, such as Aureolin, are very weak and have a value range of perhaps 2. You can never make a dark yellow.
Generally reds have a scale of 2-8. These include the powerhouse reds, such as Carmine and Alizarin Crimson. There are some weak reds, such as Rose Madder, that only reach 2 to 5 or so.
Blues have a similar value range to the darker reds, with some variations. Phthalo Blue can go as dark as 9 on the value scale. Cobalt Blue and Cerulean Blue only achieve about a 6 or 7.
Translate Value to Color in Watercolor Painting | An Example
Note the values of the deep blue shadows in the painting above. On a value scale, they achieve about an 8, even though they are painted at almost full strength.
The color base is Cobalt Blue mixed with a bit of Quinacridone Burnt Scarlet to increase the value range and give it a slight purple tint. I often use this mixture in place of Ultramarine Blue, which granulates more than this mixture.
The true black areas are a mixture of this deep blue with Phthalo Green and Carmine, also close to full strength.
The red tile roofs in the distance are painted with a dense mixture of Cadmium Orange. The same Cadmium Orange is in the plaza foreground, almost fully diluted. The water to pigment ratio is key to achieving the correct values in your painting. By knowing the range of individual colors you can mix the values you desire.
Watercolor Painting Tip: Watercolors dry lighter than when they’re first applied. You usually have to apply the paint in a value higher up the scale to get the tone you want in the end.