Thick Palette Knife Strokes in Ultramarine and White

Oil paint doesn't dry by evaporating. It hardens by slowly reacting with oxygen in the air, so a stroke as thick as these can form a skin on top while staying soft underneath for months. Here ultramarine, white and gray have been dragged across the canvas with a palette knife, leaving tall ridges and a few bare patches of weave. Fine cracks run through the heaviest paint. Every ridge throws its own small shadow in this palette knife painting jigsaw puzzle.