Some of my best plein air paintings are done in three or four hours. I initially thought I could paint the Van Gogh in two sessions, or about eight hours. But, so far I’ve spent nearly 16 hours on this painting, in four separate sessions. I found the effort much more challenging than I anticipated. Painting Van Goghs from photographs, I could finish in eight hours because I didn’t need, or force myself, to be faithful to the texture and his application of paint.