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substances that were not classified as toxic and dangerous to the environment. The focus was to develop one that was free of metal, phenol or aldehyde—such as formaldehyde or glutaraldehyde— but would also have good tanning properties. A major process simplification was achieved by moving from the three normal stages of pickling, tanning and basification, to a single tanning one. The avoidance of an acidification stage also meant the elimination of common salt from the tanning process. This was of considerable environmental significance as the presence of salt in wastewaters is recognised as being a serious problem in many countries, where controls and restrictions on the salinity of tannery effluents already in place are likely to be increased. Furthermore, because of the pH profile of the tannage, the basification stage with its attendant chemical requirements and difficulties is no longer necessary.

The original development focused on the needs of the automotive industry with the aim of satisfying all its customers’ physical and environmental requirements without compromising the typical characteristics which make leather a natural, unique and desirable product. The results, however, quickly showed that the potential was greater than just for use in automotive leather (Figure 1) , so work commenced on shoe upper leathers. This, in turn, opened new horizons for metal-free shoe uppers, including white sport shoes and water repellent leathers (Figure 2) .

Deliming does not need to be free of ammonium salts and both it and bating can be carried out conventionally. It must however be complete throughout the cross-section of the pelt, as any residual lime will affect the subsequent tanning process. Pelts are then washed at 30°C to 35°C prior to a short tanning float of between 10% and 30% based on the limed/split weight and dependent upon the thickness of the pelt and the mechanical action. Pickling is not necessary and, unlike any standard tanning system, no salt or acids are needed. The tanning product itself is added in one single dose and nothing further is required. Penetration takes between one to two hours with a complete running time of eight at which point the tanning agent is completely exhausted.

EasyWhite Tan offers significant advantages over existing systems which are of benefit both to the tanner and the environment:

• Three stages in the tanning process are eliminated • One tanning agent replaces up to five • Conventional dosing equipment can be used • Less process control is required

• Tanning process is simplified and streamlined • Between 25% and 30% faster • 50% less water needed

• Up to 30% less weight of chemicals • 80% less salt in the system.

In appearance, the grain is white and very flat with fine, closely spaced hair follicles. This flatness is partly due to the absence of pickling. There is also a noticeable absence of neck wrinkles or growth marks which will assist pairage yield for shoemakers on cut uppers. It is also quite different in one other respect from other organically tanned materials in that it is cationic in character. This cationic charge makes the leather fill out and behave in a way that is closer to chrome tanned leather than to other organic tannages and makes it suitable for a wide range of applications as shown in Figure 1. Its inherent flatness and tightness also means less retanning agents are required

TEST METHOD REQUIREMENT RESULTS Tear strength DIN EN ISO 3377-1 >/= 30 N 57 N Stitch DIN EN ISO 23910 >/= 60 N 97 N Elongation at break DIN EN ISO 3376 40-70% 52% Lastometer IUP / 9 8 8.5 Formaldehyde VDA 275 HPLC </= 70 mg/kg n.n Formaldehyde DIN EN ISO 17226-1 HPLC </= 70 mg/kg n.n Thickness in mm DIN EN ISO 2589 1.2 - 1.4mm 1.35mm