Procion Dye Staining for Differentiation of Skin and Core of Viscose Rayon Fibers

Abstract

A new microscopical technique for differentiating the skin—core structure of viscose rayon fibers is described. Slide preparations mounting fiber cross sections are stained with an alkaline solution of Procion Black HGS, which is a Procion dye recently mar keted by ICI as a chemically reactive dye for cellulose fibers. This technique is found to furnish a staining entirely selective for the skin area in a simple and rapid way. Since it is well established that Procion dyes do react chemically with cellulose mole cules under alkaline conditions, it is highly probable that the differential staining pro duced by the present technique is due to a definite difference existing between the skin and the core with respect to the chemical reactivity toward the dye employed. This differentiation mechanism appears to be quite different from that which is generally accepted to be the case in the previously described techniques using ordinary dyes. Typical results are presented for several types of cellulose rayons showing various staining behaviors. It is seen that these results are in good agreement with those obtained by other stain methods. The same procedure, when applied to a variety of fibers other than cellulosics, is found to give positive staining reactions only to wool, silk, regenerated protein, and Vinylon fibers. Although most of these findings are as yet not satisfactorily explained, reactive dye staining of this kind seems to be of much promise in the field of fiber micros copy.