Zaphod’s attention however was elsewhere. His attention was riveted on the ship standing next to Hotblack Desiato's limo. His mouths hung open.
“That,” he said, “that...is really bad for the eyes...”
Ford looked. He too stood astonished.
It was a ship of classic, simple design, like a flattened salmon, twenty yards long, very clean, very sleek. There was just one remarkable thing about it.
“It’s so... black!” said Ford Prefect, “you can hardly make out its shape...light just seems to fall into it!”
Zaphod said nothing. He had simply fallen in love.
The blackness of it was so extreme that it was almost impossible to tell how close you were standing to it.
“Your eyes just slide off it...” said Ford in wonder. It was an emotional moment. He bit his lip.
-From The Restaurant at the End of the Universe
by Douglas Adams
Life imitated art as a team led by Dr. Richard Brown of England's National Physical Laboratory perfected the material coating they dub NPL Superblack, or Ni-P black, the blackest manmade black known to humankind.
How black is superblack? Well, really, really black. It's 25 times more black than conventional black paint. It can absorb 99.7% of visible light that strikes it. For comparison, black paint absorbs a measly 97.5%, and the prior record holder was gold- and nickel-blacks, that did a close-second at 99.4%. Superblack goes so far as to absorb light you can't even see: ultraviolet and infrared. Now that’s black.
It has other properties, too, such as the ability to withstand a huge range of temperatures, making it the first useful black coating in cryogenics. It also ages better than its predecessors. Once large-scale plants are made, it will be relatively cheap. But what makes it sexy is its singular lack of brightness.
It accomplishes its amazing, ultra-velvet-like depth like this: The object to be superblackened—which as yet must be a metal alloy, glass, or ceramic—is immersed in nickel sulphate and sodium hypophosphate for five hours. Then it has a coating added to it that is made up of nickel and 6% phosphorus. The coating is then etched with nitric acid. The nitric acid etches away the small bits of phosphorus, resulting in a surface that is covered with a fractal cascade of microscopic pits. Light, happily strolling along, gets unwittingly trapped in the pits as if it had been pulled under by hungry graboids.
This surface strategy mimics the ultrablacks designed by evolution, like in the male Australian butterfly Mountain Blue Don (Papilio ulysses), whose scales are riddled with microscopic honeycomb shapes to accomplish the same thing, only organically. Now if only Brown could also master the peacock's destructive interference, he might get closer to 99.9%.
The process isn't new, it's been around about 20 years or so, but NPL's process and formulae are more precise than prior efforts, and results in surfaces reflecting 10 to 20 times less light. (It turns out that their specified 6% mixture is darker than <5% or >7% phosphate mixtures, which create little stalagmites rather than pits.) They've also been able to increase the sample sizes they are able to manufacture–from 3x3 cm to 12x12 cm.
Where is it used? Don't count on showing up with a little superblack dress anytime soon: it's stiff stuff, and intended for scientific use, in places where the slightest stray photons can mess up a sensor reading, such as star trackers (which is how spaceships maintain their position), and high-powered astronomical telescopes. The downside is that right now the stuff is really easy to scratch, which means it's not ready for commercial applications, though Dr. Brown says he's already been approached by artists and sculptors hungry to exploit this new darkness.
UPDATE: On 1 March 2007, the Rensselaer Polytechnic Institute announced its invention of silica nanorods on top of aluminum nitride (no catchy name as of yet), which may put superblack into second place.
UPDATE 16 JAN 2008: Scientists at Rice University have created a substance that absorbs 99.955% of light with carbon nanotubes. Sadly, it is as yet unnamed, but it derives its light scattering qualities from the stiff, hairlike shape of the carbon molecules. More on this when, I guess, they name it.
Apologies to uucp
, whose writeup was originally under the obscure node title "blacker than black," and which I found only while softlinking my writeup. Gods convinced me not to nuke mine.