Of the sketchbook art that I’ve seen, the colour work gets me wondering the most. The sketch I did at Hanging Rock took 35 minutes. If I’d used colour it would have taken twice as long. How on earth do artists whip up colour sketches – particularly those of people or animals – while out and about? And how do they stop the paint making the ink bleed? Do they sketch in pencil first, then colour, then ink on top? If so, do they have to do the inking by memory, because surely the subject would have moved in the meantime?
The leaf above was very obliging, not moving while I worked on it, and consenting to a second sitting in which I added colour to the ink sketch. The sketch was an experiment to see if painting gouache on top of ink would cause as much bleeding of the ink as watercolours do. Some bleeding occurred, but then I was mostly painting around the lines rather than over them. Where I painted over the cross-hatched shadow it turned the paint colour grey, but the line work is still fairly solid.
It would still probably be better to paint colour on top of pencil, then add the ink later. But that requires time and planning, which isn’t always available when sketching. Still, I’ll keep gouache in mind for times when I do have that luxury.