Goniophotometric Assessment of Bulk-Related "Optical" Carpet Streaks in Finished Nylon Carpets

Abstract

Further work on bulk-related "optical" carpet streaks is reported here, focusing on their instrumental characterization. Texturing process conditions have been adjusted to create bulk variation in both commercial staple and bulk-continuous-filament (BCF) products. For the staple items, bulk is characterized in the fiber, in the pre- and postheat set yarns, and in the carpet tuft itself. Both the staple fiber and heat-set yam methods are new. Yarns from both carpet manufacturing processes have been implanted as tuftlines into multiple carpet backgrounds, each background made with different levels of bulk. Sixty such staple and 144 BCF implants, most obvious streaks because of their bulk differences, have been evaluated by graders for intensity and shade; these grades correlate well with those ranked instrumentally ( R2 = 0.91 and 0.94, respectively) and, for the staple products, with various measures of bulk ( R2 from 0.78 to 0.95). Goniophotometry has also been used to ascribe the unique optical effect commonly seen in bulk-related streaks, that of changing shade with view direction, to the carpet's surface filament configuration.