Treasures from the Color Archive The historic pigments in the Forbes Collection include the esoteric, the expensive, and the toxic.

How blue can it get? How deep can it be? Some years ago, at the Guggenheim Bilbao, I thought I’d hit on the ultimate blue, displayed on the gallery floor. Yves Klein, who died at thirty-four, was obsessed with purging color of any external associations. Gestural abstraction, he felt, was clotted with sentimental extraneousness. But, in search of chromatic purity, Klein realized that even the purest pigments’ intensity dulled when combined with a binder such as oil, egg, or acrylic. In 1960, he commissioned a synthetic binder that would resist the absorption of light waves, delivering maximum reflectiveness. Until that day in Bilbao, I’d thought Klein a bit of a monomaniacal bore, but Klein International Blue, as he named the pigment—rolled out flat or pimpled, with saturated sponges embedded in the paint surface—turned my eyeballs inside out, rods and cones jiving with joy. This is it, I thought. It can’t get any bluer.