Everyone has heard that a black surface will take on heat faster than a
lighter surface. What everyone does not know is Kirchhoff’s law in heat
transfer, i.e. the emissivity of a body equals its absorptivity. Thus
a black object will give up its heat faster. The problem is that most
paints have a lower thermal conductivity than bare aluminum. So a black
painted surface is better than a silver painted surface but can lose to
bare aluminum. This all changes if you move from ordinary paint to a
purpose designed thermal dispersant which can exceed the thermal
conductivity of bare aluminum. Techline coatings makes them among other
manufacturers.