Been waiting on this to be available ever since it was first announced. Finally got an email last year from a paint supplier (Gamblin), and a single 37ml tube is $75... with a limit of 2! I really hope at some point that these 'rare earth' ingredients come down and it can be more readily available / cheaper. I'd seriously paint my roof and my whole house with it to keep it cooler in the summer.
Possibly a stupid question, but why would painting your roof blue help keep it any cooler than painting it white for example, which reflects more light?
Edit: Ok it turns out there's 2 parts to a cooling roof, how reflective it is, and how good it is at emitting infrared radiation (emissivity). Reflectivity of visible and UV light prevents more energy from being absorbed, but doesn't necessarily mean the material cools down well once hot. A high emissivity means the material can cool down quickly through radiation.
I cannot think of any reason why blue would ever have a lower emissivity than actual white.
Rare earths are not going to come down in price, in my opinion. They're used in too many places and have too few sources. The US has a rare earth strategy document that makes clear just how insecure supplies of these elements is.
I cannot think of any reason why a material's absorption/emission through the visible spectrum would determine its absorption/emission through the infra-red spectrum.
I dunno, how hard is it to get materials that reflect radio waves?
It's probably reasonable to talk about materials that reflect almost all the light in frequency bands of non-negligible power as effectively being actual white.
Yes, you're describing a white body, the opposite of an ideal black body. It does not exist, of course. But we can try to approximate one with materials, at least for IR through UV. Now, if we do have a pigment that can reflect X-rays... I'd definitely want my roof painted with that.
You are absolutely correct, but the ratios of their availability, because they are a byproduct, all go up by the same proportion. It's hard to avoid excesses of the less useful ones with shortages of the more useful ones.
More useful ones being things like neodymium and erbium and cerium.
Once one of them is not being produced in sufficient quantity due to being a byproduct, then it gets really expensive. That's for sure.
Indium is a bit more expensive than silver at the moment, the other two are much cheaper.
So yes, synthesis, quality control, probable patent encumbrance, and high demand, more than raw ingredient price: but it'll never be particularly cheap.
