Heat transfer of coatings

[stephenjvb]

I want to build a box that is warmed by sunlight.

I was told that aluminum in the sun is much cooler than bare aluminum, both because it absorbs less light (even infrared?) and because it is a better black body radiator than bare aluminum. Is this correct?

Ideally the surface toward the sun would absorb the most energy and radiate the least. Black paint should absorb more heat than bare aluminum, especially if it absorbs light into the infrared range, but will the paint transfer heat into the aluminum or will it act as an insulator in contact with the aluminum and just heat itself?

I will set up experiments, but I'd appreciate any information that I can get to simplify my tests.

Thanks

A small, but vocal, contingent even argues that tin is superior, but they are held by most to be the lunatic fringe of Foil Deflector Beanie science.

 

[Alkim]

You need to look for high emissivity coatings. There are commercial ones. Metals are very reflective and thus inappropriate.