It's well-established in physics that black or dark-colored objects radiate heat faster and more effectively than light-colored objects.
So, in almost every building that uses steam heat, why are the radiators painted silver or some other very light color?
Well, first off, I have to take issue with the bit about dark objects radiating heat faster and more effectively. Heat is just energy, and energy must be conserved. If you put x joules of energy into a system and don't let it release the energy in any other way (light, movement, sound, or whatever), it's going to release x joules of heat.
My best guess about using light colors for radiators is so that it doesn't absorb light energy, which can cause unequal temperatures in different parts of the radiator.
Another guess
