Effect of Fiber Translucency on the Color of Blends of Precolored Fibers

Abstract

Colored fibers can be blended together to create a spectrum of formulated yarn colors much like a paint formulator creates custom paint colors by blending dispersions of individual pigments. Unlike paint formulations, however, it is not possible to obtain a completely homogenized, uniform color with fibers because they remain separate entities on a macroscopic scale. When viewed under conditions that permit spatial or temporal integration of the discrete colors by the eye, one might expect the colors to combine much the way, for example, colored dots do on a television screen. This would require a simple weighted average or additive sort of color mixing mathematics, . but fiber blend colors follow much more closely the mathematics of subtractive color mixing, specifically the two-constant Kubelka-Munk theory. Simple experiments were performed to provide a better understanding of the color mixing mechanism operable in blends of differently colored fibers and a visual demonstration of that mechanism. The experiments show that both visual and spectrophotometric responses are linearly (additively) related to the component yarn colors in the blend only in the special cases of opaque component fibers or translucent fibers where there is no fiber overlap. For overlapping translucent fibers, the original component yarn colors form a mix according to the mathematics of the two-constant Kubelka-Munk theory, which is then additively integrated into the final blended yarn color. The two-constant Kubelka-Munk theory can be used over a wide range of fiber transparencies and degrees of overlap and can even approximate the color of opaque or non-overlapping fiber blends. Additive mixing mathematics, on the other hand, deviates rapidly from the actual visual or spectro photometric response as fiber translucency or overlap increases.