The immersion absorption of wool carpet yarn was studied to gain a better understanding of yarn scouring processes. Upon initial immersion in nonylphenol poly(ethylene oxide) (NPEO) surfactant solutions at 50 degrees C, yarn bundles became rapidly and almost completely saturated. After removal from the solution and squeezing, however, complete absorption on subsequent immersions in either an identical solution or distilled water was possible only when the EO chain length of the NPEO surfactant was ? 12. For an EO chain length of 9, complete saturation on the subsequent immersions was possible only when the surfactant concentration was ‹0.5gl^-1. Evidence suggests that the incomplete saturation phenomenon is caused by thin surfactant films that trap air in the yarn interior. The thin films are formed in the squeezing process following the first immersion.