Perhaps few people know that the acronym IKB is short for International Kline Blue, the most famous blue used by French artist Yves Kline starting in 1954. Patent number 63471, issued on May 19, 1960, by the Institut National de la Propriété Industrielle, protects the applicant’s rights to the invention called IKB.

But, is it possible to patent a color?!

No, you can’t patent colors. Kline just patented the system and process for obtaining his special blue. He didn’t do so for publicity or other trivial reasons, but simply to prevent others from using it, thus diminishing the logic and conceptual value of that precise shade of blue that only he had achieved.

But let’s see what happened first…
After a long series of experiments, Kline discovered that ultramarine blue pigment, and pure colors in general, once applied and dried, almost changed their appearance. The medium used with the pigment partially altered the original color, which lost its absolute hue, luminosity, and intensity. However Kline wanted to maintain the same luminosity and material appearance as the pure, dry pigment.

In the mid-1950s, his paint supplier, Edouard Adam, a paint merchant (as he liked to call himself) in his Paris shop founded in 1898 by his grandfather Gaston, suggested suspending pure pigment in a crystalline synthetic resin with compatible solvents such as ether and petroleum. Encouraged by this suggestion, Kline asked him to find a practical solution to his problem. So Adam consulted a chemist at the French chemical company Rhone-Poulenc, who suggested several materials, including a colorless polyvinyl acetate resin called Rhodopas M. It was also available in a 60% solution in 190-proof (95%) alcohol and marketed under the name Rhodoras M60A.
Adam experimented with the resin and in 1956 formulated a medium for Kline by adding ethyl alcohol and ethyl acetate in solution to the resin itself. Kline then set to work using this new mixture.
The new medium was versatile and could be sprayed, brushed, or rollered, or layered on a surface such as gesso. It dried quickly, forming a fragile yet durable matte finish that, like velvet, made the paint’s absorbent surface seem to dissolve into a dark, luminous liquid depth.
As Klein wrote in an unpublished document cited in Philip Ball’s book “Bright Earth,” he was struggling with the fixatives used to transform the dust into pigments:
“The affective magic of the color had vanished. Each individual speck of dust seemed to have been individually extinguished by the glue or whatever other material was supposed to fix it to the other specks and the support.” When combined with ultramarine blue pigment, this colorless medium allowed the dust to retain what Yves Klein called “Pure Energy.”

Rodhopas is no longer commercially available, but polyvinyl acetate (AYAA) can be used as a substitute. Polyvinyl acetate resins are widely used as both consolidants and coating materials for paintings, fabrics, leather, and paper. Mixtures of ethyl alcohol, isopropyl alcohol, and acetone are commonly used to dissolve PVA resins, although most organic solvents will work as well.

Alternatively, you can go to Adam Montmartre at 96 Rue Damrémont in Paris and buy a one-liter or five-liter jar of Le Medium Adam25 (but it’s quite expensive…) and create your own Kline Blue just like the original. It’s for copyright reasons that Adam named his product Medium Adam25.
As Sasha Frere-Jones stated in “What We Talk About When We Talk About ‘Yves Kline Blue,'” about the striking ultramarine shade created by Yves Klein: “This color is a famous blue, not just a blue.” […] For a painter, using IKB would be an act of reappropriation. […] An artist using Adam25 is in Klein’s territory, working around and violating its rules.

PAINT YOUR ONW CAST IN THE MANNER OF KLINE, VERY EASLY::

After many attempts, I finally found a really simple way to replicate Yves Kline’s experience with his plaster casts. By following this simple tutorial, you can discover the contact with pure, dense, and material color, the pure energy Kline referred to.
It turned out to be a truly pleasant and satisfying experience.
In this way, you can achieve the exact same color effect, with a smooth, velvety surface and an opaque blue, just like in Yves Kline’s original casts.
Use pure ultramarine blue pigment and mix it with Acrilmat. Acrilmat is a tempera fixative, available at an affordable price in art supply stores.
The best pure ultramarine pigment on the market is Kremer Ultramarine Blue Dark (Pigment Blue 29 CI 77007. Kremer Pigmente GmbH & Co.), whose chemical name is sodium aluminum sulfosilicate.

Mix about 2 tablespoons of pigment with 2.5 tablespoons of medium. You can vary the amounts, but the color paste should be smooth and homogeneous. Not too thick, not too runny.

Next, apply the color with a brush onto the dry gesso using light strokes; the color should adhere perfectly to the gesso, as Yves Kline worked this way. Let it dry for a few minutes, then mix a tablespoon of acrylic medium with half a teaspoon of pigment and apply the color again to the surface of the cast. This second layer fixes the color better.

Let it dry completely, or you can use a heat gun on a low setting. Finally, if necessary, you can further fix the color with a matte paint fixing spray (in my case, it wasn’t necessary).

Cast of Venus by FeliceCalchi are available at these  links:
Venus Medici

Small Torno of Venus

Acrilmat at this link: Acrilmat

Kremer Dark Ultramarine Blue at this link: Dark Ultramarine Blue