Collector Guide Leather Straps & Their Environmental Impact

As watch collectors, we tend to deal with a great deal of animal-derived leather products, mostly straps. For those of us who are concerned with how our consumption of leather impacts our increasingly distressed ecosystems, this guide will serve as a primer on the topic, if not a final answer to the myriad questions one faces as a consumer of animal-derived leather.

One of the more common concerns about leather production vis-a-vis the environment has been the use of animal products more generally, and whether raising animals on an industrial scale for consumption is at all wise. This guide does not address that issue. This guide addresses the chemical processes of tanning and dying leathers necessary for the commercial sale and use of animal hides, and assumes that consumption of animal-derived leathers will continue at an industrial scale for some time, if not indefinitely.

Leather is ubiquitous in the world of watches, but rarely considered beyond color and feel. Photo: David Flett

My grandfather tanned leather for a living, from a very young age as an orphaned Italian immigrant in North Carolina, and later in Northern Pennsylvania at the Elkland Tannery (Est. 1894) for the rest of his working life. Tanning wasn’t a very desirable job, because it presented an unpleasant experience all day long, stained one’s hands, smelled awful, and it was eventually known to be a very toxic to handle the materials used in tanning. My father recalled to me that one didn’t swim in the local streams on Thursdays in their little Pennsylvania town, because on Thursdays the tannery dumped its toxic waste into the waterways, which were linked directly to both drinking water and agricultural soils. The Elkland Tannery caused a significant toxic mess, the kind blindly tolerated in the early 20th Century. In the early 21st Century, we are growing increasingly aware of the toxicity of many of the 20th Century’s industrial processes, and hopefully not repeating past mistakes.

Vegetables Can Be Toxic

When it comes to leather production, the current lingo we hear most in regard to environmental impact is “vegetable tanned” or “vegetable dyed.” Vegetable sounds so benign, but let’s not be foolish, as a vast array of toxic chemicals are derived from plants. Arsenic, for example, is a naturally occurring chemical found in apple and grape seeds. Gather up enough arsenic, and you’re got deadly poison. Similar examples abound. Despite the obvious dangers of many plant-derived chemical compounds used in large-scale industry, the happy-sounding word vegetable suggests environmental safety. At the retail end, sales people and marketing materials rattle off vegetable with nary a glimpse into what that could possibly mean in actual scientific terms. Instead, we are expected to believe that, like veggies on our dinner plate, vegetable tanned and dyed leathers are healthy and safe.

These leather tanning drums are in Vincenza, Italy, and many motorcycle garment leather is died in this tannery.

But is the use of vegetables in leather processing actually safer, or does it just sound safer? There’s no simple answer, and we best not indulge generalizations where nuance is required. The variety of vegetable processes is vast, and the safety of vegetable tanning and dying varies. On the whole, however, vegetable processes tend to be safer than their synthetically derived chemical counterparts – but this isn’t always true.

Tanning Vs. Dying

There’s a difference between tanning and dying. Tanning is a process of adding chemicals (organic or synthetic) to the leather’s protein structure in order to retard biodegradation and add durability. It’s called tanning because originally tree bark tannins were used; it has nothing to do with the color tan. Dying is, as you’d likely imagine, adding pigments to the leather for color.

Tannins for leather processing are often derived from tree bark and sometimes from leaves, but not without negative environmental impact. The stripping of tree bark for tannins decimated many a forest for centuries, and the concentration of spent tannin mixtures, usually dumped into waterways, was quite toxic (as in my parent’s home town). The more common way to tan a hide is to use a solution of chromium sulfates, and these come in varying degrees of toxicity, but are all toxic once used up and in need of disposal. Today, estimates say that about 80% of hides are tanned using chrome. There are many other processes for tanning leather, but vegetable and chrome remain the main ones.

Leather dyes bind differently to the protein structures, and the chosen color can impact durability. Photo by Isaac Benhesed on Unsplash.

Dying leather also presents an array of possible processes, and the current environmental lingo you’ll hear retail sales people toss off is “vegetable dyed.” As with vegetable tanning, however, vegetable dying is not inherently safe. It can be quite safe, but high concentrations of certain plant-derived dyes can be toxic. On the whole, however, most but not all vegetable dying is superior both in quality and safety over most but not all synthetic chemical dyes. The quality of vegetable dyes is typically better due to the ways the dyes adhere to the fibers of the hide, and some colors are even more durable than others due to differences in how they bind to the leather.

Hopefully it’s apparent now that vegetable tanning and dying is often if not always preferable over synthetic processes for a number of reasons, but vegetable processes are by no means without considerable environmental impact. And what turns out to be the most important aspect of protecting the environment when it comes to producing leather (via vegetables or synthetics) is the proper disposal of the waste produced, both while preparing the solutions and once those solutions are spent.

Who To Trust?

As a relatively casual consumer, it would be difficult to go much deeper into this topic than I have already. Leather production is a highly technical topic, one that requires an expert’s knowledge of myriad leather processing schemes, a solid grasp of organic chemistry, and how the leather industry operates globally. For those of us buying shoes and watch straps, that knowledge is a bit much to take on, and most retailers aren’t going to have the answers you’d be seeking anyways. And so we might turn to third-party resources to guide us. But who do we trust?

The UN’s Leather Working Group has set out an auditing system for leather manufacturing around the world. An audit will consider impacts on a vast and complex set of overlapping ecosystems. Producing leather begins with raising (or hunting) animals, so already we’re grappling with a complex agricultural industry. From there the slaughter and the removal of hides, transportation to the tannery, the tanning, dying, finishing, and onto the disposal of waste and transportation of the hides to wholesale buyers, the production of leather goods, and then transportation to retail. It’s a lot. Every step involves another set of overlapping ecosystems, all which need to be considered carefully to reduce toxifying the environment.

This map is at the website for the UN’s Leather Working Group, and shows regions where leather production audits have been conducted.

Once audited, a production system is given a grade, basically, and those grades are almost impossible to find from any leather producer (whether there’s been an audit or not) and even harder to learn about from retailers of the final leather products, like those selling watch straps in a store.

So what do we consumers do about choosing leather that is minimally harmful? Is there a way to easily assess the leather goods we purchase? Is compliance with the UN’s audit enough to reassure us, provided we can find out? How do we know if a factory complies with such an audit, even if that audit has taken place?

This tag is available for producers who have been audited by the UN’s LWG as a means to signaling approved status.

Alas, we may have to just carry such questions around with us and do our best to learn more ongoingly, but we might also find some solutions by returning to regional suppliers.  As part of thesis of The Aesthetic Revolution, I went into the role of regionalism in securing environmental sustainability, and much of the reason has to do with access to information as it does with shipping distances and so on. It’s far easier to put questions to a small firm working nearby, one you can visit and learn more about. Obviously we don’t live in a world where you stroll down to the local tannery to get your watch strap, but we can become familiar with leather processing in our regions and we can also seek out leathers that have their origins well listed – which tends to be the case when strap makers are using regional suppliers with whom they have a more intimate and direct relationship.