Trumpler offer designer water proofing agent

The demands made on modern waterproof leathers in terms of dynamic water resistance, water vapour permeability as well as the aesthetic properties associated with leather such as handle, softness, lightness and dyeability led to Trumpler introducing the Truposist waterproofing system some twelve years ago. This comprised of two products: Truposist A (a polymer/fatliquor-based waterproofing agent) and Truposist C (a silicone-based hydrophobing agent). The products were used in conjunction with one another and allowed tanners a flexibility of use, allowing even heavily retanned leathers with excellent dynamic water resistance to be easily produced. The success of Truposist A and C quickly led to the development of Truposist D, a single 'designer' waterproofing agent which not only facilitated the production of high specification waterproof leathers but allowed its use at various stages of the leather-making process such as in neutralisation, retanning and dyeing. Truposist D utilises not only polymer technology but also functional waterproofing compounds and complex active stabilisers which allow leathers of excellent dyeability along with a pleasant, dry handle to be produced. In addition, consistent waterproofing values in excess of 100,000 Maeser flexes are easily achieved. Having said this, several other factors play a major role in achieving high specification waterproof leathers. Beamhouse processing with high levels of degreasing agents will have a marked effect upon ultimate water resistance. As, too, will the use of many chrome stable fatliquors used in pickle or tannage. Retanning agents should also be tested for their suitability in waterproof leathers, as will dyeing auxiliaries which may be based on fatty ethoxylates. As with all leather-making processes care and attention to detail such as time, temperature and float control plays an important role in achieving consistent results. Thorough washing of the leather to remove hydroscopic salts developed in the process or incorporated as 'diluents' in dyestuffs will also have a marked effect in obtaining improved water resistance and should not be underestimated. The use of hydrophobic leather is not new, with leather being widely used in drinking vessels and water carriers in mediaeval times. Perhaps one of the most interesting uses of water resistant leather is documented in the ninth century Latin text 'Navigatio Santi Brendani Abatis' which refers to the voyage of Brendan, an Irish monk who lived from about 484 AD until 577 AD and is reported to have undertaken a voyage of discovery from the west coast of Ireland to Newfoundland in a leather boat, made from oakbark tanned oxhides made water resistant by treating with lanolin and tallow. (This voyage was repeated by Tim Severin in 1976 utilising leather made by the traditional methods described). Over the past 150 years our understanding of leather-making has moved from craft status to a more scientific basis with many 'new' developments being adopted in the leather industry including the tanning drum and chrome tannage. Rapid development in chemical synthesis has also played a major role in allowing much wider options in the utilisation of chemicals specifically designed for certain leather-making processes. These developments have been most notable in the area of water repellent and hydrophobic leathers. Water repellent leathers are mainly surface treatments which allow water to be shed from the leather surface; and hydrophobic or waterproof leathers exhibit a resistance to water penetration throughout the cross-section when subjected to dynamic stress through flexing. Waterproofing treatments for leather some 30 years ago were based on fatty acid soaps and their derivatives and often were associated with causing loose leather due to the high pH application required to maintain emulsion stability. The introduction of phosphoric acid esters into fatliquoring preparations proved to be advantageous in allowing leather of moderate water resistance to be produced without the need to neutralise leather to the same degree. Polymer-based softening/ waterproofing agents were later introduced and marked a major breakthrough in the production of lightweight washable leathers. Such products, however, often imparted a 'rubbery feel' to the leather, overfilling and in some cases reducing area yield. In addition, silicone-based materials in either solvent or emulsion form were also finding use in the production of waterproof leathers although care had to be shown to avoid problems associated with finishing and an oily, unpleasant handle that could ensue if used in excessive amounts.