Chemical Technology March 2016

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Chemical Technology • March 2016 6
The technical term for it,” declare Terry Pratchett and
Neil Gaiman in their astute treatise ‘Good Omens’, “is
infrablack. It can be seen quite easily under experi-
mental conditions. To perform the experiment simply select
a healthy brick wall with a good runup, and, lowering your
head, charge. The colour that flashes in bursts behind your
eyes, behind the pain, just before you die, is infrablack.”
I imagine they were describing Vantablack, developed
by Surrey NanoSystems. There is a freaky YouTube clip you
can watch if you so desire. A crumpled sheet of aluminium
foil is rotated. On one side is an ordinary bit of reflective
silver metal. On the other … there’s a hole in the universe.
The original Vantablack absorbs 99,96 % of all light
that hits it. It has now been improved to a point that its
absorption index can no longer be measured since there’s
no way to do so.
As you watch that clip and contemplate the full haunt-
ing horror of it, you’ll want to grab hold of the scientists
at Surrey’s Advanced Technology Institute and demand,
‘Why? Why?’
And then you read Michael Vlasov’s blog. Vlasov is an
Israeli electro-optical engineer and amateur astronomer.
In a deeply detailed ‘how to’, he describes how to improve
the light absorption of his Orion telescope. “A Newtonian
reflector’s open tube (or any other OTA for this matter) is an
attractive target for unwanted stray light, which can come
from anywhere: Moon, street lights or even bright stars. This
light bounces off telescope’s inner surfaces and eventu-
ally enters the focuser and the eyepiece. As a result, the
background lightens up and the image contrast is harmed.”
The original paint in his very expensive telescope isn’t
good enough. So he describes how to take it apart and
carefully cover the interior tube of the scope with … paper.
Special black paper, but paper nevertheless.
His paper is produced by ProtoStar and is self-adhesive
flocking paper and is especially designed for telescopes. The
problem is that it’s paper and so can only cover smooth and
regular surfaces. Not all surfaces are like that.
Gerd Neumann produces a deep-black optical paint
which is effectively just chalkboard paint. They suggest –
and I’ll quote this – “To improve the effectiveness of the
colour, you can add a fixed amount of finely sifted sand,
poppy seed or flour to the paint. After this treatment, the
coating gets an extra rough finish so that even with a glar-
ing reflection of the sun or a halogen lamp the surface
remains pitch black. (Please try to figure out the mixture
ratio by yourself. The paint should be very, very smooth in its
consistency. A good starting point is a volume ratio of 1:1.)”
And then there’s the problemwith space flight. The paint
has to survive the intense high-frequency oscillations of the
launch, not losing bits and pieces that interfere with instru-
mentation, and require no maintenance for the lifetime of
the orbital instrument.
The Hubble Telescope, famously, suffered from a
2,2 micrometre ‘flatness’ in the perimeter of its main mir-
ror. This necessitated a major repair job. It was launched
in 1990 and first serviced in 1993. It’s been up there for
over a quarter of a century.
NASA developed a super black coating called — wait for
it — ‘super-black’. The basic principle of these coatings is to
use carbon nanotubes. Carbon tubes arranged tightly and
vertically are not only black, but the nature of the structure
means that light is absorbed into the tubes, reflected inter-
nally and dissipated as heat.
Very little light escapes. The problem is in creating these
dense vertical nanotube structures. The process is a familiar
The blackest paint
that sucks all light
by Gavin Chait