The Effect of a Surface Barrier on Uptake Rates of Dye into Wool Fibers

It is shown that any surface barrier to the entry of a dye into a fiber must modify the form of the uptake-time relation, the barrier exerting its greatest influence in the early stages of sorption, but becoming progressively less important as sorption proceeds. This is manifested by an initially concave-upwards tendency in the uptake-timel curve. The analysis, which takes account of variable diffusion characteristics of fibers forming the ~asemhly, is applied to the uptake of Naphthalene Orange G by wool, and a small but definite effect is found, which could for instance be attributed to the epicuticle.