Using cadmium red, I started painting the foreground (photo 1). While the paint was still wet, I added a little Prussian blue into the red at the bottom, mixing it on the painting (photo 2).
The background was going to be painted in a chromatic black mixed from the cadmium red and Prussian blue. Because I didn't want to risk this running into the foreground, I turned the sheet of paper upside down on my easel (photo 3). I then mixed the red and blue together on the painting, using some water to help blend the two colors. The result (photo 4) is a background that looks black from a distance, but up close reveals subtle variations in color and direction of brushwork.
Now the background's done, let's paint the apple...
