Abstract

The rate and extent of uptake of C.I. Acid Yellow 83 onto chrome grain leather were enhanced by means of pretreatment with chitosan, the extent of this enhancement being greater for chitosan formate than for chitosan acetate. The pH of application of the polyaminosaccharide had a marked effect upon adsorption of C.I. Acid Yellow 83 with pH 4 yielding maximum dye uptake; pretreatment also improved the dry cleaning fastness of the dye on chrome grain leather. Optical micrographs of the grain side of chrome grain leather which had been pretreated with chitosan and dyed using C.I. Acid Yellow 83 showed the presence of a distinct dye-chitosan ‘layer’ situated at the fibre surface. SEM micrographs revealed that pretreatment also improved the fullness of the leather. Pretreatment with the cationic polymer was found to reduce both the rate and extent of uptake of CI. Acid Brown 75 and CI. Acid Direct 106 onto chrome grain leather possibly as a result of the high substantivity and low diffusional power of the two dyes.