Yves Klein developed IKB in 1956–1960 while obsessively seeking a blue that matched his mental image of pure colour — a colour that was nothing but colour, without the dilution of conventional binders. The specific resin solution he found with Edouard Adam preserved the optical properties of dry ultramarine powder. Klein patented the colour in 1960 — one of the few successful attempts to legally claim a colour.

Infinite, immaterial, and absolute. Klein described IKB as representing "the void" — an immaterial blue depth without beginning or end. He associated it with sky, sea, and space as expressions of a limitless blue that transcended physical reality. Psychological engagement with IKB paintings is characteristically one of dissolution — the sense of falling into rather than looking at a surface.

Klein's IKB works created a new model for what painting could be — not representation, not expression, but pure colour experience. His "Anthropometries" (women covered in IKB pressed onto canvases as living brushes) created controversy that combined performance, painting, and gender politics in unprecedented ways. The attempt to patent a colour raised philosophical questions about ownership of the immaterial that remain unresolved. In 2012, Pantone was widely (incorrectly) reported to have successfully patented a colour — public fascination with the idea continues.