Abstract

Attempts to establish a workable method of evaluating the strength of vegetable tanning materials go back to the early part of the 19th century but the first method to achieve any real credence was that of Löwenthal developed in the 1860s. The problem was first addressed on an international scale at the London meeting of 1897 at which the first leather chemist’s society was founded. Many subsequent meetings have failed to produce agreement on an international method of analysis, making this subject the longest standing source of dispute on the international leather scene. This paper discusses the three Official Methods which currently co-exist, highlights some of the problem areas and makes some suggestions about their resolution. A more recent problem has been the use of these methods for estimating the tannin content of syntans, a purpose for which they were not originally envisaged and are unreliable, but for which no serious alternatives have yet been promulgated.