International Klein Blue: The Paint Recipe Behind a Colour

In January 1957, a Milan gallery hung eleven blue canvases on its walls. They were the same size, 78 by 56 centimetres. They were coated in the same pigment. Visitors still picked a favourite, and the prices on the wall were not the same.

The artist was Yves Klein, and the blue was not a pigment so much as a method. Three years later he put that method in a sealed envelope and filed it with the French government. The colour he named after himself, International Klein Blue (IKB), is really a lesson in how a binder, a surface and a recipe decide what a colour looks like.

Why the blue kept going dull

Ultramarine is an old pigment. It was once ground from lapis lazuli and cost more than gold, a story we cover in why Renaissance painters were obsessed with ultramarine. Klein's pigment was ultramarine, and the pigment was not his problem.

The binder was. According to the Centre Pompidou, Klein wanted to keep the raw intensity of the powder, and traditional binders dulled it as they dried. A pigment is only a pile of coloured grains until something holds it to a surface. Whatever does the holding also coats each grain and changes how it handles light.

Klein wanted the look of loose powder, with each grain left free to shine, on a canvas that could hang in a gallery. In his own words, as Artetrama quotes him, the grains should stay unaltered, with their autonomous possibilities of irradiation intact.

These four swatches are my own screen stand-ins for that range, from a bright, dry-looking blue to a deep, sealed one. They are not measurements of any Klein painting. Treat them as a way to see the gap, not as the colour itself.

A paint dealer in Montparnasse

Klein did not solve this alone. He took the problem to Édouard Adam, a colour merchant in Paris's Montparnasse district, and the two worked through binders until one held.

The winner was Rhodopas M, a synthetic resin made by the chemical company Rhône-Poulenc. Later accounts describe it as a polyvinyl acetate resin thinned in alcohol and ethyl acetate, which lets the pigment keep a matte face. Adam's firm still sells a binder of this kind as Médium Adam 25.

Klein then rolled the paint on. The Centre Pompidou notes he used a roller to avoid any texture, so the surface reads as one velvety plane. The edges of the panels were rounded, and the canvases stood off the wall. In Milan they hung about 20 centimetres out, so they seemed to float.

That is the whole trick. The pigment is ordinary. The resin lets it stay loose and bright, and the roller keeps it flat. Put the same powder under a glossy varnish and you get a different blue.

Eleven identical paintings, eleven prices

Klein's earlier shows had gone badly. In 1955 and 1956 he exhibited monochromes in several colours, and critics read them as decoration. So for Milan he used one colour only.

The show, Proposte monocrome, epoca blu, opened at the Galleria Apollinaire in January 1957. It was the first public outing of the blue. Klein later wrote that the paintings, identical in appearance, were nonetheless perceived by the public as entirely different from one another. Each carried its own price, and buyers chose according to their own sense of which one was best.

You can call that a stunt. You can also call it a clean experiment in simultaneous perception. If eleven matching objects can feel different, then colour is not sitting in the paint. Part of it is sitting in you. Our piece on simultaneous contrast covers the mechanics.

Paris came next. Klein showed monochromes at Galerie Iris Clert and other work at Galerie Colette Allendy, and released 1,001 blue balloons over the city to mark what he called his blue period. Sources disagree on some of these 1957 details, so treat the exact sequence with care.

The envelope

On 19 May 1960, Klein filed a Soleau envelope with France's national industrial property office, INPI. The Centre Pompidou gives the envelope number as 63471. A Soleau envelope is a dated deposit that proves you had an idea on a given day. It is not a patent.

This is the detail most retellings get wrong. Klein did not patent a colour. Under French law, a colour cannot be owned. What he registered was the technique: a specific pairing of ultramarine pigment and Rhodopas M binder.

That distinction matters if you work with brand colour. A shade belongs to nobody. A recipe, a process or a pairing with a context can be protected, and sometimes a shade can be argued into a trademark. We follow the second path in the red sole trademark wars.

Exclusive blue, exclusive black

IKB gets compared with Vantablack, the carbon-nanotube coating whose artistic rights Anish Kapoor secured in 2014. The Pompidou makes the same comparison, and the difference is instructive. Vantablack is a patented industrial material. IKB is a pigment anyone can buy, held in a binder anyone can buy. Klein's claim was to a way of doing something, and the sealed envelope was closer to a dated signature than a lock. Our article on the Vantablack feud shows how differently that played out.

Sponges, models and a velvet surface

Once the paint worked, Klein pushed it everywhere. He covered models in IKB and had them press their bodies against canvas, in the Anthropometries of 1960. He painted copies of the Venus de Milo and the Winged Victory of Samothrace in it. He also made sponge sculptures, and the porous forms took the loose, matte colour much as the canvases did.

Klein died of a heart attack in 1962, aged 34. His blue lasted only a few years in his hands, and the recipe is what remains.

What a designer can take from it

You cannot reproduce IKB on a screen. A hex value describes light your monitor emits. IKB depends on powder scattering light off a rough, open surface. The distance between those two is the same trouble you meet when a teal turns muddy in print.

Still, three lessons transfer.

• The medium changes the colour. Test your blue on the real surface, in the real light. A swatch on a monitor is a sketch.
• Surface is part of the palette. Matte and gloss versions of the same hex are two colours to your eye. Our colour converter will translate formats, but it cannot translate finish.
• Name what you can protect. If you build a brand colour, document the whole system: the values, the materials, the rules for use. That is the part that is yours.

If you want to explore the blues themselves, start with the contrast checker to see how a deep blue holds up against white text, then look at the individual swatches on pages like /colors/002fa7.

Klein never owned blue. He owned a sentence in a sealed envelope that said how he made it. That turns out to be the stronger claim.

Sources

• The untold story of the International Klein Blue (IKB) of Yves Klein, Centre Pompidou
• The Story of Yves Klein's "International Klein Blue", TheCollector
• Getting to know IKB in depth, Artetrama