In the late 1950s, Yves Klein created a series of monochromatic paintings using a resilient and powdery ultramarine pigment. It was of great significance to him, symbolizing the physical manifestation of cosmic energy, and he patented the color under the name “International Klein Blue” (IKB). Klein subsequently applied it to a series of large sponges that, for him, served as a metaphor for art and the creative process. He either attached these to his canvases as relief elements or affixed them to wire stands as sculptures. In addition to blue, Klein also used particular hues of deep pink (IKP) and gold (IKG). Together, he believed these colors to be a holy trinity of equivalency, stating, “Blue, gold, and pink are of the same nature. Any exchange at the level of these three states is honest.”

Label from Giant Steps: Artists and the 1960s, June 30–December 30, 2018