Stainless steel has emissivity of 0.12. It means it only absorbs 12% of radiation and reflect the rest of the 88% as well as tranmitting the 12%. Now if you heat the stainless steel to say 300 Celsius. It won't transmit the 300 Celsius but only a little of it. This is why thermal imagers can see it colder than it actually is (and you have to adjust the emissivity setting). But if you paint the stainless steel black, the thermal imager would see its true temperature. Now question, how come mere painting the surface black can make it transmit 96% of the heat radiation? We know that painting it black can no longer make it reflective. But heating it is an internal process within the steel.. so how come without black pain, it can only transmit a fraction of the heat. With it painted black, it can transmit majority of the heat? What has the surface reflectivity got to do with the internal events of the sample?