While many abstract paintings are about expression or purity, 180 Colors is about nothing so lofty. Richter used a systematic approach to determine the rich variety of colors: he produced its 180 different colors by combining the three primary colors to get twelve hues and then mixing fifteen tones of each varying from light to dark. The surface, composed of glossy enamel paint, is flawless and shiny. Another key element of this painting is literally not there at all: From a distance, an optical illusion of gray dots seems to hover at the corners of the colored blocks.