Written
A brush is forgiving. It lets you go back into a passage five times and still look fresh. A knife does not. It puts down one flat plane of colour with a hard edge, and the second pass either covers the first or ruins it.
What it gives
Edges, first of all. Water has edges: the line where a lock gate meets its reflection, the lip of a weir. A knife makes that line in one movement.
It also keeps colours apart. Dragged across a dry layer, the paint catches only on the ridges of the weave and the colour underneath shows through as it is, not mixed.
What it costs
About a third of what I start goes in the bin. There is no rescuing a knife painting that has gone grey. I have made my peace with that rate.
