Gloss Meters

Gloss Meters
Color and Gloss (SCE and SCI Methods)
Even for objects composed of the same materials, variances may be seen in the colors due to differences in the gloss of the surfaces. For example, why is a duller blue color seen when sandpaper is applied to a shiny or high gloss blue sample?

Light which reflects directly back (but opposite angle) from the light source, as if by a mirror, is called specularly reflected light. The rest of the light that is scattered in many directions is called diffuse reflectance. The sum of the two is called total reflectance. Shiny objects have higher specular reflectance/lower diffuse reflectance and the opposite is true for dull objects. The total amount of reflected light is always the same if the materials and color are the same. Therefore, if a glossy blue plastic part is sanded, the specular reflectance is reduced and the diffuse reflectance increases.