Consolidation of highly degraded silk artifacts is difficult because there is no entirely satisfactory treatment. One option recently introduced to the field of conservation is Parylene-C, a polymer whose unique gas-phase deposition method allows extremely thin (below 1mum), highly conformal coatings to be applied. The purpose of this research was to evaluate the long-term effect of light on silk fabrics coated with Parylene-C, including change of color, stiffness, tensile properties, and appearance in the scanning electron microscope (SEM). The effect of Parylene-C depended on fabric construction, color, and initial strength. A thin coating (less than1mum) made very fragile, naturally aged silk easier to handle although fabrics became somewhat stiffer; smooth, dark colored silks became slightly irridescent. When fabrics coated with Parylene-C were exposed to simulated daylight, the coating continued to consolidate fragile silks but did not reduce degradation if ultraviolet light was present. Because coating with Parylene is an irreversible process, the decision to treat a fragile textile must be carefully made; however, for highly degraded silks, this treatment may be appropriate if an alternative method is not available.