A Statistical Examination of Influences Affecting Lightfastness of Dyed Fibers—The Effect of Fiber Polarity

Abstract

Comparisons of the lightfastness (LF) of ranges of dyes, each respectively between a pair of fibers, are described. The data give scattered points when plotted as LF on one fiber vs. LF on another fiber, hut regression lines show significant differences between the slopes of the plots. The differences are interpreted as evidence of the effect of the polarity of the fiber polymer, which, it is suggested, infiuences the charge on the auxochrome groups of the dye molecule. The higher the polarity of the fiber, the more is this charge reduced, the result being to reduce the difference in LF between all the dyes applied to the fiber. The effect is observed with all types of fiber examined: cellulosic, protein, and synthetic-polymer. It may have technical value, by indicating that to achieve more uniform LF of all dyes on a given fiber, the dipole moment of the monomer forming the fiher polymer should be increased.