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Comment by wolframhempel | Hacker News Reader

I'm curious: What are the use cases for these super light absorbent blacks?

You can paint a hole in the side of mountains and fool roadrunners into running in(to) them, then perhaps feast on the fruits of your labor. Or paint holes in the ground to fool your nemesis'. Though if Looney Tunes taught me anything, it's that it only works when you don't want it to work.

~"Sensitive optics"

A list of examples: https://en.wikipedia.org/wiki/Vantablack#Applications

It looks very interesting when you use it in constrast to other colors. Under the right conditions it creates an effect of "absence" that the human brain (at least mine) doesn't have a reference for.

Huh, kind of like how standing next to a highly sound-absorbing material can be painful or disorienting, making your brain think that your ear is damaged or blocked somehow?

yeah I'd imagine it's similar.

In my family we took a piece of christmas decoration one year and painted it in Black (v3) and it was eerie. It was just hanging there among all the other glowing/shiny stuff but it was impossible to really make out its contours or even be sure it's really there. :D

Coating insides of optical instruments, especially infrared cameras.

Yup. The research group I work with builds a lot of custom camera parts (mostly 3D printed) for different projects, and we keep a bottle of Black 3.0 around to coat internal surfaces. We'll pick up some 4.0 shortly.

It's a quick and easy way to guarantee light-tightness and kill internal reflections.

On my Ikea Hemnes corner desk I painted most of the hutch, plus the bezels on the 2 24" panels in it. It's like the displays are floating in the void.

I could add things like car dashboards to the list, to avoid annoying reflections.

And also for better "Pepper's ghosts". Which is based the same effect that makes you see your car dashboard reflected in the windshield.

Painting satellites so they do not annoy astronomers. Bright satellites show up as lines in long exposures. A wide field sky survey image may be full of them.

I think there is a reason why the satellites are reflective. One thing that comes to mind is to not overheat.

Hard to dissipate heat when conduction and convection are basically null.

It's why Starlink satellites already switched away again from black painted satellites (that light up like christmas trees on IR anyway), to having sunshades that reflect the light away at angles pointing away from Earth, to keep the light away from both astronomic observation and the sats.

Heat radiates as IR and other such, even without air.

Fun fact, black both absorbs and radiates heat faster.

Only if it's also "black" in the IR spectrum.

In fact, an object that is completely reflective in the IR spectrum, but black in the visible spectrum would get really hot really easily.

The reverse is also true! An object that is black in the IR, but reflects the visible becomes cooler than ambient temperatures!

Of course, have you touched a black surface? If it wouldn't radiate it wouldn't be hot ;)

Your sense of heat when touching things is mainly due to conduction, not radiation, isn't it?

Hmm the radiator that is keeping my legs warm would disagree with you, but I'm not a physicist so I will simple shut myself up :)

Well it's a pretty big difference in terms of intensity, sitting next to a radiator for a few hours is comfortable, but touching one would give me a burn in a matter of seconds (screw you whoever decided that my apartment must be warmed to 25 degrees)

I think you want them to show, just not too bright.

Otherwise you get stars mysteriously disappearing.

And thus, the reddit "alienz are cloaked and spying on me and mine!" forums start.

Home theaters using projectors is the use-case for me.

But I stick with triple black velvet which seems to be even blacker than these paints due to the 3d texture to it being able to trap and absorb more light.

I’m building a telescope and would love to use it

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