There’s a big fight in the art world. The debacle began with sculptor , who among other things, was a designer of the ArcelorMittal Orbit sculpture that writhes in the skyline of London’s Olympic park. Kapoor is known for portraying holes and voids in his work, so when he heard about a company that claimed to have developed the blackest black, he wanted a piece of the action.
Vantablack is a material made of carbon atoms fashioned into tiny tubes that form a sort of nanoforest, which absorbs more than 99.96 per cent of light that enters it. Luckily for Kapoor, its developer, Surrey NanoSystems, was keen to work with an artist, but just one, because it is a small outfit and Vantablack still needed further development to be a practical artistic material.
So in 2014, the company signed a contract with Kapoor, giving him exclusive rights to use a version of Vantablack in artworks. That enraged other artists, including , who is known for paintings with a brightly coloured, pop-punk feel. Semple decided to release what he dubbed the pinkest pink. His only proviso? Kapoor was outlawed from using it.
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Now, the blackest black is one thing; you just need a material that absorbs more light than any other. But coloured things absorb only a particular sliver of light, comprised of different wavelengths. So can you have a pinkest pink, or indeed any kind of “colouriest colour”? You might have two bright pinks, for instance, that absorb slightly different wavelengths. Who says which is the pinkest?
For his part, Semple says he’s tried to simply cram in as much colour into his paint as possible. “The big, big thing is I created a special acrylic base medium with a clever colour chemist to mix colour into,” he says. “It’s really, really special: it means the paints we make can hold more pigment than any other in the world.”
The eye of the beholder
Fair enough, but objectively judging which colour is the deepest or darkest or purest, is no easy matter. A good starting point, however, might be to define the shade of colours that our eyes are most sensitive too. Colour perception is the job of photoreceptive cone cells in the retina at the back of the eye. They come in three types, broadly sensitive to red, blue and green light. So could we work out the exact wavelength of light they respond to and find a physiological way to define colour? Unfortunately not, according to at the University of Washington in Seattle, because our perception of colour depends not on any one cell, but on the relative magnitude of signals from the cone cells.
The best we can do is to ask people to look at wavelengths of a colour and tell us which they find the most uniquely pink, say. But even then, there is trouble, because people have different ratios of the different cone cells and so might not agree on what shade of pink is the pinkest.
There is one colour that might offer hope, though. In 2002, Yasuki Yamauchi, then at the University of Rochester in New York, and his colleagues asked two people with very different ratios of cones to look at different wavelengths of yellow light – they both agreed that about .
Semple now , but he didn’t pay any special attention to Yamauchi’s findings. His paints are “made in a process more like cooking than lab science”, he says.
As for Vantablack, its claim to be the blackest black is under threat. Although it reflects less than 0.04 per cent of visible light, that happens only when the light is shining from a point perpendicular to the surface. As of 2015, there’s a new black on the block. “Dark chameleon dimers” is made of gold nanoparticles and absorbs about 99 per cent of all light from all angles. That still leaves room for improvement, and the quest to portray nothing continues.
