Emissivity variation with surface color?

>
> Emissivity is a surface property, largely involving the material to a
depth
> of a few wavelengths of the emitted photons.
>
> Painting aluminum with black paint greatly increases its emissivity.

    That's questionable.  I think all oil base paints have about the
same emissivity at the IR wavelengths involved with radiation at nominal
temperatures.   That is, temperatures humans can tolerate, such as 300
K.

   Now a 'black' auto may get hotter in the sun than a white one.  But
sunlight peaks at a green wavelength, while radiation from the auto
peaks at a much longer wavelength.

   Ron