In an attempt to explain why a matt surface of aluminium is a better emitter/absorber of blackbody radiation than shiny surface of aluminium, my university lecturer suggested to me that: By brushing a metal surface to create a matt finish, the surface of the metal becomes rougher. Rougher means there is a lot more curvature of the material, thus creating essentially lots of lightning rods with strong electric field around them. Photons somehow interact with the "lightning rods", and become more likely to be absorbed by the material. Photons can go through multiple scattering on the rough surface, which also contribute to absorption. Does photons interact with the electric field? If so, how does it interact with it such that it increases chances of absorption? What are some other surface properties that can affect the efficiency absorption? Also, would a insulator have higher emissivity than a conductor?