Approaches to quantitating the results of differentially dyed cottons

The differential dyeing (DD) method has been a subjective method for visually determining immature cotton fibers. We attempted to quantitate DD results and offer an efficient means of elucidating cotton maturity, without visual discretion. Image analysis of cotton color obtained with a scanner was performed and compared to spectrophotometrically measured color. Low, Medium and High micronaire (Mic) cotton standards were dyed, and we determined that blending the cotton yielded more precise color measurement; with the mean red, green and blue (RGB) values for a low Mic sample being: 101.6 +/- 23.9, 83.1 +/- 22.0 and 98.3 +/- 23.1, respectively; while blending yielded RGB values: 121.6 +/- 9.0, 98.8 +/- 8.6 and 116.0 +/- 8.9, respectively. Comparing RGB values to Mic, it was found that R and B color parameters do not show a trend, but G values decrease with increasing Mic indicating a decrease in G dye uptake with an increase in maturity. The conventional L*a*b* color space values were also obtained for the dyed cottons and compared to RGB and Mic results. The %CV for a* values are higher compared to L* and b* measurements: similar to 31.9%, 18.9% and 8.6% for low, medium and high Mic samples, respectively. L* and b* decrease while a* increases with Mic, indicating an increase in R dye with an increase in maturity. The DD Bath method was found to be reliable, with R showing the greatest variances. G and a* values obtained were found to be the best correlation of differences in Mic.