Black magic
Stare into the void that is Vantablack: a nanoparticle coating that could soon be coming to a satellite or art gallery near you...
WORDS: JOHN C SILCOX
PHOTOGRAPHY: CRISTOFFER RUDQUIST
Try to imagine something so black that it sucks up light. Sounds like science fiction, doesn’t it? It’s not. It’s Vantablack, the world’s darkest man-made substance, which absorbs more than 99.6 per cent of radiation in the visible spectrum. Basically, it’s the closest thing you’ll find on Earth to a black hole. The coating was originally developed for use on satellites, but since its launch in 2014 it has been applied to a wide range of products, from military material to optical machines, as well as luxury items such as watches and cars. In April, a spray version was released, and will be used for projects by Turner Prize-winning artist Anish Kapoor, who is famous for working on void-like sculptures, paintings and installations.
Surprisingly, Vantablack isn’t the creation of NASA, CERN or some other large international scientific research centre or company. It was, in fact, developed by a small British company called Surrey NanoSystems, and is produced on an industrial park in Newhaven, East Sussex. ‘We’re doing some really exciting work here,’ explains Ben Jensen, the company’s founder and chief technical officer, showing us around the facility. ‘With barely 20 full-time staff, we are achieving results nobody else in the world can. It’s been a whirlwind few years but we’re not resting on our laurels yet. We’re continually trying to push the limits of possibility.’
The company has a long list of projects still under embargo. For Jensen and his team, the future looks black. For once, this is good news.
The secret behind Vantablack’s light-absorption properties lies in nanotechnology. The super-black material is in fact composed of billions of nanotubes, which are tall tubular structures made up of carbon atoms. ‘An easy way of thinking about Vantablack is to think of a forest,’ says company founder Ben Jensen.
‘It is a forest where the trees are of normal height but the width of a blade of grass, all closely packed together. Light rays penetrate the surface but get trapped in between the black trees, and never bounce back out, which gives it such a black aspect.’
‘Vantablack is applied in a similar way to conventional thin-films,’ says Ben. ‘But unless you’re a scientist that won’t mean anything to you. Essentially this means that to apply something that’s incredibly thin you need to use special reactors, and ours are the best-performing in the field.’
The process used is called chemical vapour deposition (CVD) and this is how it works: you seed a material in a chemical catalyst, which is almost like minuscule grass seed, then heat it up inside the reactors. Then you activate the catalyst with carbon, which will make it push out carbon nanotubes. Above, a scientist places a material into the CVD reactor. On the right is an inside look at one of the reactor chambers.
Nanotube coatings have been around for a few years, and other researchers in this field have managed to create similar substances to Vantablack on a small scale. However, the real breakthrough at Surrey NanoSystems was that the team were able to work at low temperatures.
‘Originally the problem with creating nanotubes was the fact that you must heat the material you are using to a very high temperature,’ explains Ben. ‘At NASA they have had some success but they can’t achieve anything under 700C. At that type of heat, most metals and plastics will be destroyed.’ Vantablack, on the other hand, can be applied at temperatures as low as 450C, and 100C for the spray version. This means it works with silicon microchips, quartz, copper and aluminium.
Vantablack S-VIS is a sprayable version, so it can be applied under controlled conditions in air (within an enclosed and filtered spray booth). To the left, a scientist is building up the coating over a number of passes until the correct thickness has been achieved.
The applied coating then passes through a number of chemical functionalization steps to bind it together and change its density. Above, a scientist shuts the door on a special reactor, which cooks the coated material from 100C to 300C.