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Comment by loaph | Hacker News Reader

I interpreted this along the lines of it not being a pigment, rather it's black because something about it's physical structure at a small scale causes light to not reflect back. Adding a thin coating of gold would not necessarily change that structure so it would continue not reflecting light.

^ pure conjecture

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I believe it's something called "structural absorption", similar to what happens on birds of paradise feathers [1]

[1] https://www.nature.com/articles/s41467-017-02088-w

I'm way out of my depth here, but I think this comparison to the birds of paradise feathers makes the most sense in terms of me visualising what Nxylon would look like with a thin metallic coating

I wonder if this pattern is considered similar to fractals? Or would that work even better? I recently learned that we have figured out how to produce fractal light from lasers as well which sounds quite interesting and useful.

Maybe the reason radio waves travel poorly through trees is due to the leaves having a fractal-like structure as well? And since light is also just electromagnetic radiation too, it makes sense that this phenomenon could also be used to absorb light itself, if I'm understanding correctly. I wonder if this is how stealth paint on aircraft works?

> Adding a thin coating of gold would not necessarily change that structure

My confusion is that I would normally expect a layer of gold not to permit any light to pass through. The underlying structure wouldn't be receiving any light, so there would be no photons to trap. Apparently a layer of gold can be applied thinly enough to transmit appreciable light, though.

Gold foil can be beaten to under 2 micrometers.

https://en.wikipedia.org/wiki/Gold_leaf

This part of the article confused me, because what does a black pigment do if not "inherently prevent light from escaping"? That's kind of just the definition of absorb.

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