As previously stated in this thread early paints contain “metallic salts and oxides” and these paints were used to protect the fibre glass structures from the degrading effects from suns rays UV etc. I was once told the black paint used originally on ray domes is a lacquer.
It allowed the thinnest application of paint to protect the fibre glass composite structure from elements without impeding the radars performance. The paint needed to be black as black was the only pigment that offered a protective solution without compromise of the radar. Later I have seen ray domes painted black in a MIL- spec non magnetic Black polyurethane paint on F111 and C130s perhaps out of tradition ?
My 2 cents
