Damage to materials by continuous wave (CW) irradiation of an infrared (IR) laser is dependent on thermal transfer, resulting from absorption of laser energy into the material. Under laser illumination conditions, the thermal radiative properties of a material are often not constant. Reflectance, for example, can vary dramatically as a result of thermal decomposition of paints and coatings. The Air Force Research Laboratory Laser Effects Branch designed and fabricated unique reflectometers for making accurate measurements of surface reflectance under conditions of continuous heating. A number of structural materials, paints, and films were tested to determine their temperature dependent reflectance characteristics in vacuum and laboratory ambient environments. The experiment series produced temperature-dependent reflectance data needed for accurate computation of laser coupling for thermal control surface degradation analyses. Previous prediction algorithms relied solely upon ambient, room temperature reflectance data to determine the thermal response of paints and films, oftentimes leading to inaccurate results. Much was learned about the breakdown of typical aerospace thermal control materials in vacuum and ambient conditions. Temperature-dependent 1.31 micrometer laser reflectance models, developed from the in-vacuo data, are presented for nine coatings (paints and films) on aluminum and titanium substrates.