The history of fatliquoring is outlined and the effects of fatliquoring are specified as being primary -- the interactions between the fatliquoring components and the tanned leather (collagen) fibers; and secondary -- the softness of the leather. From the experiments carried out in the course of this study the conclusion has been drawn that for optimum fatliquoring of the leather the greasing quantities are often larger (ca. 8%) than those required theoretically. Ways to improve fatliquoring are demonstrated. The measurement of the sound made when the leather is bent is used electroacoustically in order to assess the softness of the leather which, it is assumed, is considerably influenced by greasing -- AATA