1. The problem statement, all variables and given/known data I have a university project that involves comparing various paints with regards to how they affect the insulating properties of houses. As part of that I would like to measure the emissivity of the paint for a variety of wavelengths. Unfortunately I can not simply heat up a sample of the paints for this because I would like to measure emissivity in steps of 50 nm or so up to 300 or 250 nm, which is in the UV part of the spectrum. So my question is, if I were to use a monochromator to select a narrow wavelength range of light, and then determine the fraction of that light that undergoes specular and diffusive reflection from the painted surface, would 1 minus that fraction be a good estimate of the emissivity of the paint for that wavelength range?