Mike Redwood

Columnist

International Leather Maker


World Leather Day 2024, as seen across social media, was a big success and demonstrated how so many companies, organisations and individuals were enthusiastic to come together to honour the enduring and unique qualities of leather with a common language that would have been impossible only a decade ago.

Steadily, we are starting to see this reflected in other ways like popup displays, school visits, fashion school support, trade show activity in leather specific and associated areas, company statements and, even more important, reflected in new product offerings. The leather industry must battle the pain of the current downturn and maintain momentum with ever greater creativity increasing the reach and depth of the general understanding of leather.

The three Rs

The theme of this year’s World Leather Day was “Repair, Reuse, Repurpose”, emphasising the qualities of leather that make it ideal for a circular society. By extending the life of leather goods in these ways, we can reduce environmental impact, and this is why the pioneer of circular thinking, Walter Stahel, started by talking about the benefits of product life extension.

In our industry, the word “longevity” is now used to define all this and this is apparent in the comments made by those interviewed as part of World Leather Day. Consumers and designers alike all talked unprompted about much loved leather items that they had kept for years or had been passed down from a parent or grandparent. In these interviews, there is little mention of repair, reuse or repurpose: the articles are still fit for purpose.

Some of this is a testament to the quality of the design and the original manufacture. Leather most often has to cohabit with other materials such as textile linings and threads, metal zips and wooden frames and, frequently, the failing that leads to a need for repair lies in a poor choice of these items or a poorly designed construction. If a race to short term profit means poorer hardware, less durable threads and synthetic linings have started to be used, even by the supposedly better brands, then everyone suffers.

Leather artefacts

My colleagues at the UK-based Leather Conservation Centre are starting to see these issues in their everyday work. Their very existence as an organisation speaks to the fact that so much of the world’s history can be interpreted through artefacts made of leather over thousands of years. Nearly all are vegetable tanned or some form of raw hide such as parchment and very few are “worn out”. It is floods and fire that mostly do the damage and, if the items are left without air below ground or water, leather products will survive as we see with ancient Roman goods and currently with products appearing from burial mounds being released to archaeologists in the Asian Steppes as the Permafrost melts.

Old leathers will biodegrade slowly over 50-75 years if left for mould and bacteria to take hold. Unlike plastics, which we now discover will break down into smaller, microplastic particles that end up in the food chain, leather is harmless while it waits to degrade. Leather made in the last 200 years as production advanced from general theories of “astringency” and trial and error to measured use of strong acids and alkalis to speed things up, along with new materials and concepts, creates most of today’s conservation difficulties.

Most of the wholehearted rush into the world of “modern leather making” has positively moved leather to an engineered product where the customer can rely on it being within specification. While that focus has been on making certain the leather will move smoothly through the shoe or leather goods factory, over my life in the leather industry, longevity of the finished article has rarely been mentioned. Durability in terms of abrasion resistance, tear strength and finish adhesion are always considered and the gulf between leather and synthetics is apparent when looking at only these. But, to be certain unintended consequences do not arise in the longer term, we need to add in longevity in its widest sense.

Unintended consequences

The best example of the unintended consequences of technology advance has to be “red rot”. In the 19th century, Western tanners started to use far more catechol tannins such as mimosa and quebracho without realising there could be a problem, one which was compounded with new synthetic dyes being fixed with a pH adjustment for which initially sulphuric acid was used. With the advent of more modern shaving machines, vegetable leather tanned with catechols easily iron stained and, again, the first solution was sulphuric acid.

As the century passed, major libraries began to observe the bindings of their books disintegrating. Major studies were convened to understand what was happening. To increase the complexity, even more air pollution from SO2 and NOx had to be considered particularly when libraries were using gas powered lighting. If the final leather ended with a loading of acid and pH of under about 3.2, the tannins were not strong enough to stop the acid breaking down the collagen structure into a red-brown dust. Once started, the acid breakdown continued in the leather.

These studies soon helped bookbinders obtain leather made with methods not prone to red rot, but the conservation of 100 years of problematic production continues to be a challenge for the Leather Conservation Centre and others. Meanwhile, leather lost permanent market share in bookbinding. It’s clear that 20th century leathers and finishes are starting to impact conservation in a much more complex way with the arrival of chromium tanning, along with syntans and new fatliquors and dyes.

I often refer to a quote from 2011 by Pete Lankford, then Design Director for Earthkeepers and Timberland Boot company: “While there are plenty of things to be concerned about in the leather making process, the products stand the test of time. Leather wins hands down over anything you can think of. If you can buy a pair of boots that last twice as long as a synthetic alternative, you’ll end up with half the environmental impact in the long run.”

Footwear sustainability is difficult as there are usually multiple materials involved. Synthetic soles, linings and plastic welts do not last like leather. In general, recent decades have seen leather increasingly paired with poorer materials in terms of threads, linings and other components. This is a nuisance for conservators, but it is a much bigger problem for tanners determined to promote longevity. If our customers pair it with components that lack quality and cannot be easily repaired, then they are damaging a fine material through thoughtlessness.

If you are interested in collaboration with or other support for the Leather Conservation as they plan research into handling 20th century leathers and looking for simpler treatments for red rot, then contact info@leatherconservation.org.


mike@internationalleathermaker.com

Follow Dr Mike Redwood on Twitter: @michaelredwood

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