The incorporation of purified high-pressure carbon monoxide prepared single-walled carbon nanotubes (HiPco SWNTs) into the bulk of space environmentally durable polymers at loading levels >= 0.05 wt% has afforded thin films with surface and volume resistivities sufficient for electrostatic charge mitigation. However, the optical transparency at 500 nm decreased and the solar absorptivity increased with increased SWNT loading. Besides showing a loading dependency, these properties were also dependent upon film thickness. The absorbance of the films at 500 nm as a function of SWNT loading and film thickness was determined to follow the classic Beer-Lambert law. Based on these results, a simple empirical relationship was derived to provide a predictive approximation of these properties. The molar absorptivity determined for the purified HiPco SWNTs dispersed in the polymer by this simple treatment was of the same order of magnitude to reported solution determined values for HiPco SWNTs. Crown Copyright (c) 2005 Published by Elsevier Ltd. All rights reserved.