I divide my canvases into squares, then I paint a square at a time. I change the color slightly in each square, but I try to keep the tonal values the same. A color’s tonal value is how dark or light it is. You can kind of see the tonal value if you squint your eyes. Keeping the tonal values the same is difficult, because as paint dries it can change colors, usually making the color darker than what I mixed. This makes my painting difficult.
Above is a photo showing the same sections of a painting. When the indicated square was first painted and dried, the paint contracted a bit, leaving a few tiny spots of canvas showing through. When I noticed the spots, I tried to touch them up. I picked out what I thought was the right color from my palette to do it, but when the touch-up dried, it was a lot darker, making the square look mottled. When I saw what had happened I decided to repaint the whole square.
I mixed up the color but made it a lot lighter than I wanted, hoping that when it dried it would end up being the color I desired. The indicated square on the top of the photo is what it looked like when I repainted the whole square. The indicated photo at the bottom is the same square after the paint dried. You can see that it became a lot darker once the paint dried, but the color was close enough to what I was wanting.
Blues and grays seem to especially darken as they dry, and the painting I am currently working on has a lot of grays, so I have been running into this darkening problem a lot.
The squares that you see are part of storm clouds. You can see what the painting looks like so far by clicking on “Current Work” at davidmarchant2.ca