The optical response of sulfuric acid anodized 5657 aluminum alloy coatings was determined to be greatly dependent upon trace and alloying element concentration. An improved method for WDS analysis of anodized coatings was developed to preclude processing errors and improve spatial resolution since it was shown that the possibility of contamination and/or coating modification must be considered in the development of sample preparation procedures and electron beam parameters. Measured element concentrations were compared with reflectance data to determine the affect of each on absorptance. Silicon and zinc concentrations were much higher than expected, the source of these elements being the substrate 5657 Al alloy. Both of these elements play a role in absorptance and the glass forming abilities of silicon may also affect the structural characteristics of SAA coatings produced on 5657 Al alloy.