Mapping the distribution of spin finish oils on nylon carpet fibers is the focus of this investigation. Nylon 66 fibers of two modification ratios, 2.4 and 3.0, manufactured for the carpet industry, are compared to similar fibers pulled from dyed and finished carpet tufts. Fibers are treated with osmium tetraoxide to provide contrast in scanning electron microscopy. After wet processes of dyeing and finishing, the carpet fibers have a significantly lower amount of finish, but the concentration of oil on the carpet fibers is 47% that of the raw fiber. Higher relative concentrations of finish oil components are found at the fiber core compared to the surface. The finish is believed to diffuse into the core during application on the melt spinning line, and the morphology of the fibers in the core allows retention of more residual finish oil components. Capillary action appears to be a driving force for wicking of finish in this application system, because significantly higher relative concentrations of oil are found in the valleys compared to the tips of the multilobal fibers. Side-to-side variations exist in the finish distribution, which are attrib uted to the single applicator system, where the finish has to wick around the fibers and diffuse through them to coat the side opposite the applicator.