A more Minimalist branch of Ab-Ex is found at Patricia Sweetow Gallery on Geary Street, where the 68-year-old German artist Joachim Bandau presents a careful selection of monochromatic watercolors and drawings and geometric lead sculptures. In his works on paper, Bandau achieves a rich black surface from a meditative process of layering. The artist switched from graphite to watercolor after he developed acute Lateral Epicondylitis (tennis elbow) from all the physical labor that the drawings required. At once simple and specific, the watercolors educe an uncommonly placid depth.