Bob's permutation theme overlaps on both his paintings and his serigraphs. Robert's original serigraphs and prints deviate from realism to a means of graphic storytelling. Each print deals with the "permutation" of one image turning into another. They often highlight the camouflaging aspects of natural colors surprising the viewer with transformations from shape to shape in a rhythmic progression across the composition. Kercher has produced 80 works with this "permutation" theme with 39 of the editions sold out.