July 30, 2025

Do not be a science denier

The latest print and digital edition of ILM (July/August 2025) devotes considerable space to the amount of fossil fuel material used in leather. “Deplasticising leather” mostly discusses this in terms of surface coatings but notes that fossil fuels can still be found deeper into tannery chemicals. Tom Hogarth adds an illuminating companion article in which he says:

“If leather is going to differentiate itself from synthetic materials and those partially synthetic materials that hope to displace leather’s market share, an evolution towards higher biobased content is a must; leaning into the natural benefits of leather.”

There is both an immediate truth and a wider lesson in this statement. In processing hides and skins into leather tanners have always used a mix of chemical and mechanical processes. In the main it was brains and vegetable tannins but this widened as smoke, alum and lime were added to create a wide range of useful materials. Tanners were almost certainly the first biochemists with a willingness to learn both the outcomes and the implications.

This chemistry will have largely evolved through trial-and-error. It created a group of tanners, metallurgists, perfumers and pharmacists who over time became the experts in practical and applied chemistry while the subject itself continued to be taught as philosophy.

The advent of organisations like the Royal Society of Arts and the Royal Society of Chemistry and the very fact that the man who discovered synthetic dyestuffs in 1856, William Henry Perkin became a liveryman of Leathersellers’ at the age of 23 via the patronage of his artisan father symbolises the bridge between chemistry and craftsmanship. It reflected how science — particularly synthetic chemistry — was becoming integral to leather as both a practical and prestige material.

Volume production

Making leather in large volumes and tight specifications to meet the demands of growing populations, increasingly living urban lives, was required. Updating the glacé kid process to make it more affordable and eliminate the consumption of millions of eggs yokes by each glove leather tannery was sensible, as was the speed and accuracy involved in moving to chromium tanning at the end of the 19th century. And it was admirable that it was a tanner who studied in the laboratory in his own tannery who uncovered the bacterial content of dog faeces in bating that promptly saw the introduction of an enzymatic substitute soon after.

Improvement through better science was a good thing. It would not be fair to blame scientific progress in the leather industry for the malaise Tom Hogarth describes.

The problems lie in the adoption and use of that technology. How thorough was the tanners’ consideration of leather’s place in the material world and what is unique about leather in this new context. More of that thinking might have pushed tanners to be at the forefront of the sustainability campaign rather than following behind. It might have pushed them to work with chemical suppliers to keep their leathers as natural as possible. To celebrate rather than suppress their characteristics.

But at some stage tanners missed the point and became more interested in selling leather than emphasising any of its organoleptic qualities. My hand is up; I have been part of these “errors” for 60 years.

All my career we were told every hide and skin would end up as leather. In the 1980s I even published a long-forgotten newsletter (The World Leather Bulletin) in which an agricultural economist detailed how human population had been outpacing leather supply and asking subscribers to consider the implications. We were not the first as the same calculation led DuPont to create their poromeric Corfam in the 1960s. It is a fair question why the industry ignored the bigger picture implications.

Instead, the response was a desire to hide even the minutest blemish in heavy pigment coats, to push good hides into corrected grains replace moss backing on splits with PU laminates.

It has taken only thirty years for the leather industry to lose at least 30% raw material utilisation with much of the rest being discarded at some cost. It is hard not to think a lot of this has been self-inflicted.

Synthetics from petrochemicals have been the main culprit. Read “Consumed: How Big Brands Got Us Hooked on Plastic” by Saabira Chaudhuri to see how major companies such as Coca-Cola, Unilever, McDonald’s, and Procter & Gamble created the modern dependence on single-use plastics in the name of progress; and in so doing shifted the burden of plastic pollution onto consumers.

Articles once made of traditional craft materials such as wood, wicker, leather, metal and ceramics that were replaced with plastics are now under pressure to be designed for sustainability.

Meanwhile leather has lost out, as has the craft sector supported by it. But the current issue with plastics is what preoccupies Tom Hogarth as it looks like a transition is underway to:

  • Bioplastics or certified biodegradable materials.
  • Renewed interest in reusable, repairable, and traditional craft-based solutions.
  • Reduced use, with a preference for minimalist, multi-use items.

 

Despite this global plastic use is still projected to rise (backed by an even bigger lobby trying to replace declining consumption of oil in transport and energy). Recycling cannot close the loop for all plastics and full replacement of conventional plastics across all product categories will be hard: it is more likely in packaging than materials like leather.

Nevertheless, a growing consumer intolerance for plastic pollution must be exploited by leather and that leather must demonstrate the core leather qualities of authenticity, integrity, natural beauty and durability.

This means that tanners must take full responsibility for their leathers and seek out chemicals that match their true objectives of meeting contemporary consumer needs at the same time as promoting the truths of a natural raw material. As well as looking for future technologies I recommend a thorough study of how leather was made before the chemists got to work in the 1800s. There is a lot of lost technology that needs reimagining.



Michael Redwood

Leather chemist, writer, and advisor on responsible leather manufacturing and material strategy. This article was originally written for ILM.