1 Ik Piki: Here’s a shady bar. Let’s go in.
1 Serron: Let me do the talking.
2 Serron: Hey everyone! We’re looking for a black market to sell some recreational drugs!
2 Iki Piki: Smooth.
3 Bar patron: This is Triana. Every market is a black market.
4 Serron: But we still want to sell under the counter.
4 Bar patron: Ah. You want the Vantablack Market.

I toyed with the idea of adding a bit more context to the bar patron's statement in panel 3:

3 Bar patron: This is Triana - there are no laws here. Every market is a black market.

Mainly to remind people that Triana is a lawless world. But then I figured you're smart enough to have remembered that important story fact for this long.

Vantablack, by the way, is a material surface coating made of vertically aligned carbon nanotubes, basically a bit like the pile of a carpet, or the flocking of velvet material, but on a microscopic level. When light hits the surface, it bounces around among the carbon nanotubes, unable to escape, until it is absorbed and the energy converted into heat. It's essentially like black velvet flocking, but at a much finer scale, and so even more effective at trapping light. Vantablack absorbs 99.96% of all light that hits it, which makes it significantly more black than any other known substance. It was developed and is produced exclusively by British company Surrery NanoSystems.

Normal matte black paint absorbs around 97.5% of the light that hits it - in other words it reflects 2.5% of incident light. Vantablack reflects only 0.04% of incident light, which is 62 times less. So black paint is 62 times more reflective than Vantablack.

Objects coated in Vantablack become virtually impossible to see, except as what appears to be a two-dimensional black shape. Surface details and three-dimensional shapes become invisible, because there is not enough light reflecting off them to make the shape apparent to our eyes. Have a look at this photo of a crinkled sheet of aluminium foil, partially coated in Vantablack:

(Creative Commons Attribution-Share Alike 3.0 Unported image by Surrey NanoSystems, from Wikimedia Commons.)

The black area is just as crinkly as the rest of the foil - you just can't see it because the Vantablack coating is absorbing all the light. And before going any further yes, this is the sort of black coating that Hotblack Desiato probably used on the sun-diving stunt ship for his band Disaster Area, in Douglas Adam's The Restaurant at the End of the Universe.

But Vantablack is a real thing. And because it affects the way we perceive objects, naturally artists have a desire to use it. Besides being directly deposited onto surfaces, Vantablack is also made into a sprayable paint - Vantablack S-VIS - which produces more randomly aligned nanotubes and hence has a slightly higher reflectivity than surface deposited Vantablack. In 2016 Surrey NanoSystems exclusively licensed the British artist Anish Kapoor as the sole person allowed to use Vantablack (specifically S-VIS) for artistic purposes.

This caused some uproar in the artistic community. They saw it as rather like a company making blue paint and then saying that only Anish Kapoor is allowed to use blue paint, and no other artist. Fellow British artist Christian Furr commented in an interview with the Daily Mail that he had "never heard of an artist monopolising a material. All the best artists have had a thing for pure black – Turner, Manet, Goya … This black is like dynamite in the art world. We should be able to use it. It isn't right that it belongs to one man."

Another fellow British artist Stuart Semple responded to Kapoor by producing a paint known as PINK, touted as "the world's pinkest paint". He allowed anyone in the world to acquire and use it... except Anish Kapoor. Purchasers of PINK are required to make a legal declaration confirming that: "you are not Anish Kapoor, you are in no way affiliated to Anish Kapoor, you are not purchasing this item on behalf of Anish Kapoor or an associate of Anish Kapoor. To the best of your knowledge, information and belief this paint will not make its way into that hands of Anish Kapoor."

Despite this precaution, Anish Kapoor managed to get his hands on a sample of PINK. Literally. He posted the following photo on his Instagram feed:

View this post on Instagram

Up yours #pink

A post shared by Anish Kapoor (@dirty_corner) on Dec 23, 2016 at 2:32am PST

Yes, that's Anish Kapoor's middle finger, dipped in PINK.

In the next stage of this increasingly mature and non-petulant artistic dispute between two calm and rational beings, Semple produced another unique paint, containing shards of ground glass, implicitly daring Kapoor to dip one of his appendages in that.

Ah, artists. The world would be a less interesting place without them.