Colorimetric and Hydrophilicity Properties of White and Naturally Colored Organic Cotton Fibers Before and After Pretreatment Processes

It is widely known that conventionally grown cotton fiber/fabrics/apparel has chemical residues on the cotton which may cause cancer and some other health related troubles. It is also certain that organic cotton production does not consume most synthetically compounded chemicals (fertilizers, insecticides, herbicides, growth regulators and defoliants) which are suggested for only conventional cotton production. Therefore, organic cotton production lead to much more environmentally cotton fiber production in comparison to conventional cotton fiber growing. So, in this chapter, colorimetric (CIE L*, a*, b*, C*, h°, K/S, and whiteness properties etc.) and hydrophilicity properties of studied two white (Nazilli 84 S and Aydin 110) and three naturally colored (Emirel, Akdemir, Nazilli DT-15) organic cotton fiber types was investigated before and after scouring (with NaOH), conventional bleaching (with H2O2) and the combination application of scouring and bleaching (scouring + bleaching) processes in comparison with their greige (un-treated) counterparts. Greige (un-treated) Akdemir naturally colored organic cotton fiber displayed the reddest (with the highest a* value), the yellowest (with the highest b* value) appearance, the highest chroma (the most saturated), the lowest lightness (the darkest) and the highest color strength (the strongest color yield) and therefore the strongest color shade amongst the studied greige (un-treated) naturally colored organic cotton fibers. After scouring process, all three naturally colored organic cotton fibers congruously exhibited darker [with the lower lightness (L*) values and higher color strength (K/S) values], slightly redder (slightly higher a* values) and slightly less yellow (slightly lower b* values) appearance in comparison to their greige (un-treated) counterparts. Overall, it can be concluded that solely bleaching process (without any prior scouring process) and combination sequential usage of scouring and bleaching processes (scouring then bleaching = scouring + bleaching) generally did not significantly affect the color properties of studied naturally colored organic cotton fibers leading to similar close colorimetric performance with their greige (un-treated) counterparts. So, after the bleaching process, scoured naturally colored organic cotton fibers which darkened due to the scouring process roughly turned back to their original colorimetric levels of greige (un-treated) versions. In this case, if the naturally colored organic cotton fibers are blended with the normal white and off-white organic cotton fibers or other cellulosic fibers, applied bleaching process does not cause a significant color change in the naturally colored organic cotton fibers and this indicates that they will approximately remain at the same color property levels as their greige (un-treated) counterparts. Moreover, the bleaching process following the scouring process slightly increases the hydrophilicity values of both white and naturally colored organic cotton fibers leading to more hydrophilic fibers.