The "Oxidation Paintings" is a series of "paintings" done by coating canvases with wet copper paint and afterwards urinating on them, urine which oxidizes and changes color. In most cases, the urine does not belong to Warhol, but to his friends. According to Bob Colacello, Warhol once said: "It's a parody of Jackson Pollock", alluding to Pollock's legendary emission into Peggy Guggenheim's fireplace.