Techno-colour dreams: New recipes are making hues deeper, darker, brighter

Where textiles and fabrics once drove this industry, spurring humans to experiment with mushrooms, minerals, fossil fuels and lichen through the industrial age, the new frontier, as with so much else, lies at the intersection of technology and climate change.

New blacks are being invented. New whites are reflecting so much light that they’re altering the temperatures of the surfaces and spaces they cover.

A key difference is that most of these cutting-edge colours are coatings. They are not the traditional paints made by combining pigments with solvents and resins. Instead, they are materials covered in nanoparticles that interact with light in new ways.

Let’s start with the familiar Vantablack. Most people will remember the row when its creator, the British engineering company Surrey NanoSystems, granted exclusive artistic rights to the artist Anish Kapoor, in 2016. Some may also recall the feud that ensued as British artist Stuart Semple vowed to make blacker blacks — not to mention pinker pinks and “colourier colours” — for sale to all artists except Kapoor. (He has made good on some of those promises, and we’ll get to those colours in a bit.)

But what was lost in the noise of this standoff was a key detail: nanoparticles were doing what pigments had been unable to. They were forming tiny forests of particles that could absorb (when black) and reflect (when white) far more light than any existing paints.

Vantablack, for instance, absorbs so much of the light around it (99.965%) that textures and granular details are “erased” from view. The result is a sensory void that could boost performance in space satellites and stealth weaponry, among other things. (It was first produced, after all, as an improvement on a NASA technology developed in the previous decade.)

The whiter whites, meanwhile, reflect up to 98.1% of light. They could change how cities battle urban heat island effects, says Bivas Saha, an associate professor at the International Centre for Materials Science of the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR).

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The whitest whites are, quite literally, the coolest colours around.

Last year, Saha’s team developed an ultra-white paint that can reflect over 96% of sunlight, using nanoparticles. It keeps surfaces 7 to 10 degrees Celsius cooler than surrounding areas.

In 2021, scientists at Purdue University created the whitest white known today. It can reflect 98.1% of visible light (as opposed to the 80% to 90% of commercial white paints).

Crucially, both these whites will likely be easy to apply — unlike Vantablack, which can only be applied using high temperatures of 100 to 400 degrees Celsius, and a specialised reactor from Surrey NanoSystems. Where Vantablack needs to be durable for use in space and weaponry, “easy application is a necessary criterion, if we want to use these whites to paint buildings,” as Saha puts it.

Purdue’s white is now being fine-tuned to make it thin enough to coat cars, planes and even spacecraft, as well as to make it more durable and dirt-resistant. But how was it made?

The team, led by professor of mechanical engineering Xiulin Ruan, tested over 100 commercially available materials and settled on barium sulfate. This is a chemical made from barite, which is used in radiation protection. It is also used to produce the white in lotions and sunscreens, and it is used to line photo paper.

Saha’s ultra-white, meanwhile, uses nanoparticles of another highly reflective chemical compound, magnesium oxide.

It will be a while before either white makes it to a rooftop. Saha and his team are still researching their new shade’s effects in a real-world setting, “though we’ve tested its durability in the lab for over a year”. Eventually, scaling up will involve manufacturing and creating demand, so that costs can eventually fall to more manageable levels, he adds.

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What’s interesting about this range of new approaches is that, unlike previous generations of dyes and paints, these rely on tricks of physics rather than chemistry.

The vanta in Vantablack, for instance, stands for Vertically Aligned Nano Tube Array. It uses microscopic carbon nanotubes (CNTs) that are 300 times taller than they are wide, arranged vertically. This is the forest within which light is trapped.

MIT produced its far-darker material by growing the carbon nanotubes on a surface of chlorine-etched aluminium foil. The use of the foil means that the CNTs can also be grown in far lower temperatures, making it more accessible (though still quite technical to use).

To put the colour to the test, Diemut Strebe, an artist-in-residence at the MIT Center for Art, Science and Technology, used it to coat a 16.78-carat yellow diamond, for an art installation at the New York Stock Exchange in 2019. Titled The Redemption of Vanity, the idea was to make the most reflective material known to man, this one valued at $2 million, completely disappear. And it did simply vanish into its dark background when coated.

“CNT forests of different varieties are known to be extremely black, but there is a lack of mechanistic understanding as to why this material is the blackest. That needs further study,” Brian L Wardle, professor of aeronautics and astronautics at MIT, said in a statement. “I think the blackest black is a constantly moving target. Someone will find a blacker material, and eventually we’ll understand all the underlying mechanisms, and will be able to properly engineer the ultimate black.”

Meanwhile, Kapoor’s artistic monopoly has ended. MIT’s blackest black is available to any artists who would like to experiment with it.

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As for Stuart Semple and his colours for almost all, he seems to have meant every word. In 2016, he launched Culture Hustle, which aims to make more vivid hues for use by all artists (except Anish Kapoor).

Working with an astrophysicist, a chemist, forensic scientists and artists, his Black 4.0 and White 2.0, launched in 2023 and 2021 respectively, are among the world’s darkest and brightest acrylic paints. He and his team have also created the world’s pinkest pink.

His “superbase” is a medium developed in the Culture Hustle lab and designed to pack in more pigment per millimetre than standard artist’s acrylics. His pigments are ground to a finer dust than most, with particles reduced to about one-thousandth of a millimetre.

For Black 4.0, he and his team also created a special pigment called Black Magick, which dries flat and matte, something black acrylics and oil paints don’t do.

Semple is now innovating in an altogether different direction: he is working to create a paint-formulation algorithm that will allow artists to make any colour in the world with a handful of his hues. “The future of paint isn’t artist buying different colours. It’s buying a few potions that an artist can mix together to make whatever colour they want,” he says. With a handful of colours, one could make millions of shades, he adds.

That’s quite a shift from the earliest innovations, in which humans mixed chalk, soil, animal fat and burnt charcoal to make a few base shades, more than 40,000 years ago. For more on how we got from there to here, read the story alongside.