A dirty business? Tanning – now and in the future (part one)

19th September 2024

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Mike Redwood is a visiting professor at the University of Northampton and writes columns for leather and sports magazines throughout the world. Originally a leather chemist he transferred to marketing while working with British leather specialists Pittards. He has worked in Italy, Latin America and France for historic names such as Booths, Rosati and Barrow Hepburn and later for more contemporary ones such as ECCO, ADOC and Acushnet (FootJoy and Titleist). We are pleased he has brought his expertise to Real Leather. Stay Different. The opinions expressed are his own and not necessarily those of RLSD.

During my career it has sometimes seemed that tanners enjoyed the distinction of the reputation that comes with the smell and pollution often attached to leather tanning. It shows that only when your hands get dirty, and a few other things in passing, can the world’s needs be met.

Many tannery districts like Bermondsey in London and the Swamp in New York City were originally dumping areas for hides from the slaughterhouses. Tanneries followed. So most often the odours and the vermin came from unwanted flesh, hooves and bits of meat rather than anything to do with the tanning.

But these early tanners often washed their hides clean of blood and dung by hanging them out in a stream or river. Process and street names in France, Germany and Spain reflect that. This meant tanners had to be downstream and preferably downwind of densely inhabited areas.

Tannery workers often became outcasts in these communities and when they had free time, spent it together. And when tanneries moved out of the cities, as they did from New York to the Catskills, they did not help matters. The irresponsible way, even for those times, with which they destroyed huge swathes of forest to access a few hemlock trees and blocked mountain streams with waste is remembered 150 years later. Not a good look for the industry. Once the hemlock in the Catskills was used the tanners moved on to the Adirondacks. Not a great look.

The processes of leathermaking were not obnoxious, unless cleanliness and hygiene were ignored. Many large sets of tannery pits found themselves surrounded by community housing with little complaint. The Romantic poet Samuel Taylor Coleridge wrote This Lime-tree Bower my Prison in a garden overlooking the tan pits of a large tannery. He lived in a cottage at one corner of the tannery and often wrote in either the tanner’s garden or his library. He mentioned the “dark satanic” colour of the oak bark pits he could see over the low fence but never complained of odours, nor stopped enjoying parties with his publisher and family there.

The industrial revolution changed matters. More leather was required including a lot for quite new purposes. Oak was a slow tannage and getting harder to obtain. Newly discovered extracts could often be shipped to the tanneries as extract rather than bulky bark, and the use of stronger acids rather than organic ones speeded the process. Big plants were built and soon water power was replaced by steam and then electricity. The immediate environment suffered.

Speed and efficiency became the mantra and brought the industry a raft of new machinery. Wilhelm Eitner, the director of the Austrian Imperial Research

Station for the Leather Trades, was the first to look seriously at sodium sulphide as a depilatory in the 1870s although its uptake was only partial until the start of the 20^th century. With sulphide added, unhairing was reduced from weeks to days, but the fact that sodium sulphide easily created the rotten egg smell of hydrogen sulphide the signature odour stays as the legacy of tanning. Big tanneries in and around growing urban areas were definitely recognised as notoriously obnoxious.

Trial-and-error biochemistry tested many materials and one success was the use of dog faeces for cleaning hair roots and unwanted proteins out of the hide after unhairing. Both its collection and use, especially in large tanneries where sizeable volumes were used, sullied the image of tanning, and is used against leather to this day. By the time we started the 20^th century Joseph Turney Wood and his German colleagues had replaced the faeces with synthetic pancreatic enzymes after some outstanding research. But it was actually much of the new chemistry like sulphide that maintained and increased the poor reputation surrounding tanneries.

Today, the high percentage of hides that are transported as wet blue around the world means that an enormous amount of leather is finished in tanneries with no unhairing stage. Visitors can be safely guided through without special footwear or concerns for odours lingering on their clothes. Long gone are the days when I was fully rigged in clogs and overalls. It was soon possible to discard them as was the case with the ultra-thick soled welted footwear that was the choice of US tannery proprietors.

RLSD says: Tanneries were, indeed, pretty grim places in the early days of industrialisation. As indeed, were many other manufacturing facilities.