[yownie]

radiative sky paint

https://hackaday.com/2023/07/03/cooling-paint-you-can-actual...

[netsharc]

Using CaCO3 which is calcium carbonate, like the article.

This science-lecturer-esque guy is using Barium Sulfate: https://www.youtube.com/watch?v=dNs_kNilSjk