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2 cows walking through water under a bridge, they look scared.


By Cathryn Wills



For anyone interested in understanding what they're buying, scrutiny is required on all materials - be they animal, plant or synthetic based.  This article, co-written by me, Cathryn Wills, founder of Sans Beast, and Emma Hakansson, author of Sub-Human coming in 2021, animal advocate, model + founder of Willow Creative Co - focuses on transparency of raw material – specifically animal derived leather processing + what synthetic / vegan ‘leather’ actually is.  We’ll walk through how they’re both made, their environmental impact, their biodegradability potential + touch on the terminology that is applied to both options (aka ‘natural’ versus ‘faux’).  We're not here to convince you that synthetics are the answer to environmental problems (we know they are not), however we do believe the playing field needs to be a little more balanced when it comes to conjecture around what is deemed 'natural' in the world of animal derived fashion.



Let’s start with the animals. Homo sapiens kicked off the first agricultural revolution around 10,000 years ago.  We moved from being nomads, to living within villages + farming. This meant domesticating animals, selectively breeding them so that we may have a herd that was most easily manageable, least likely to rebel. From hunter-gatherers to farmers, our relationship with animals fundamentally changed. The second revolution brought increased ‘productivity’ with machines + access to cross border markets. The third – the one we are arguably still living within - involves genetic engineering, pesticides, fertilisers, factory-farms, antibiotics + a relentless drive for profit, irrespective of the cost to the environment, humankind + non-human animals. It’s within this most recent revolution – we don’t believe the last – that our relationship with non-human animals became even more skewed. This is a big part of why our labelling of leather as ‘natural’ is questionable – today, there are 371 million bovine animals killed and skinned. 60% of all mammals on the planet are live 'stock', 36% are human, and a paltry 4% live in the wild.  This in itself, is far from natural + it's not sustainable. But we’ll get back to that in Part 2.  

With an increasingly sophisticated marketing machine ever-spinning around us in each waking moment, it’s hard to know who’s telling the truth + where to choose to spend our money. It is however an accepted reality, that animals who are farmed are considered to have several ‘co-products’. Animal skin turned into leather is considered by the meat and dairy industries as a ‘co-product’ rather than a ‘by-product’, as it is sold for a profit, valuable to these industries. Therefore, when leather has its environmental impact measured (with one of the metrics being CO2 emissions), the inputs and outputs of animal farming must be included in the equation, as they are considered part of the manufacturing process of leather.  




See formulation of data here.

Let’s discuss how we take what (or who) was alive, and turn this into a material that will last. Tanning is a manufacturing process which converts large pieces of skin to a material that will not rot + disintegrate over time. It exists to make an organic material inorganic, unable to effectively biodegrade as it normally would. For animal derived leather, there are two primary ways to tan skins, one is vegetable tanning + the other is chrome tanning. 

Vegetable tanning, producing vegetable tanned leather, or what’s commonly called ‘veg tanned leather’ – is tanning with plant-based materials such as tree bark + natural tannins. The flesh of the animal is removed from their carcass, their hair or fur is removed, and then the tanning takes place. As a result of this plant-based approach, this is considered the most environmentally friendly way to tan animal skins. It is time consuming, and therefore often considered expensive. The end result is often thicker and less pliable, the colours can be limited + some inconsistency can occur in tone + hue. To some, this is all considered part of the beauty of vegetable tanned leather. It will eventually biodegrade, to a high degree - though not entirely, even according to leather industry reporting + studies – which is another reason this form of tanning is popular for those who want to carry + wear animal-based leathers. Some studies have found that in the creation of vegetable tanned leather, the impact isn’t so much better than conventional tanning. Trees used for tannins have to be cut down, it’s perhaps more water intensive. Less than 10% of the worlds leather is veg tanned. 

The chrome tanning process is the more popular option across the globe  - used in 90% of leather production because it is time efficient, it allows for a spectrum of colours + it ensures consistency of these colours, which is key when you’re mass producing shoes, clothing + handbags. It also provides a more waterproof surface than veg tanned leather – again, important for commercial wear+ tear reasons.  Much of the tanning industry is based out of some of the poorest countries in the world, where workplace safety + environmental health are not highly regulated. Sean Gallagher has made an excellent film called The Toxic Price of Leather, set in the top leather producing city of India,the fourth largest leather producing country in the world. It’s worth a watch, if only to prompt you to ask – ‘where does my leather come from?’  Even if you’re not curious about the animal provenance of leather – the human and environmental impact is compelling to learn about. 

As with all tanning, vegetable or chrome, the first step from raw skin to leather is the removal of flesh from the skin. Then, the hide is salted, which is essential to halt decomposition. Hair is removed using either calcium oxide or lime. Chromium salts are used in the tanning process, along with a lot of water, to get the hide to the ‘wet blue’ stage. This is the base from which the colouring starts. The colouring can occur in drums, and it can also be pigment dyed – or a combination of both. Pigment sprayed on to the surface is paint, and as per any paint, there is a chemical equation that goes into this – impacting material toxicity and biodegradability. If the leather has a patent surface this is achieved with a polyurethane coating to give the final hide a high shine.

With chrome tanned leather being most common, let’s stop and look at it a little longer. Not only does it not effectively biodegrade – breaking down by only 45% in leather industry studies – it comes with serious impacts, some of which are highlighted in Gallagher’s film. Here’s a quick rundown for now: chromium VI is a human carcinogen known to cause cancer when inhaled. Unsurprising then, leather tannery workers are shown to have higher rates of cancer, as well as a host of other health problems. These problems don’t impact workers alone, but in countries like India and China (China is the biggest leather producing country), sometimes their whole community.   Tanning leather has serious human rights implications. It’s worth noting, the Leather Working Group has been taking strides in addressing these human and environmental crises, though the slaughter aspect of animal leather will of course always be inherent to it.



Data via Tannery Magazine

On to synthetic ‘leather’ – which of course, is not leather at all, but a painted / coated fabric. It’s considered the ‘faux’ to animal skin’s (not so) ‘natural’, or ‘real leather’, so let’s look into it. The two most common materials on the market in the synthetic space are PVC – poly vinyl chloride + PU – polyurethane. PU is more common + increasingly so. PVC is a synthetic plastic polymer. It’s durable, doesn’t conduct electricity + is cheap to produce; all facts that have made it prolific in everyday use – it will almost certainly be in the piping of your home. It is a thermoplastic polymer, and its production + use is considered toxic. It’s also difficult to recycle. PU is considered the more eco-friendly of the two– by far. It doesn’t contain any chemicals that interfere with endocrine and hormone systems, nor does it contribute to pH change in soil or water as PVC does. Used in fashion, it does not get washed or shed like synthetic garments do – with these being a serious oceanic issue today (largely due to the fishing industry), and it can be recycled easily. 

The PU we use – as we can’t speak for all PU fabrics in the market – is a painted surface (generally) on an acrylic fabric base.  We say ‘generally’ as the base fabric may change, but the majority of fabrics from our supplier are on a manmade knitted base, the knit construction gives greater flexibility + a softer hand-feel than a woven base.  The painted surface has chemicals in it (paints are made of pigment + binder + solvent), and these are tested to REACH standards as well as Prop65 standards, to ensure they are not dangerous to the health of the planet + its inhabitants. 

PU is certainly not perfect. Like chrome tanned leather, especially if it’s patent leather, it won’t biodegrade – no synthetic materials will (yet!). It is, most often – but not always – derived from fossil fuels. But – and there’s a big but – it is indisputably less environmentally impactful to produce than all animal skin leather, by the data. The Sustainable Apparel Coalition, which has a unique + renowned data set on the eco-impact of all materials, shows PU synthetic ‘leather’ production to have less than half the impact of cow skin leather.  Considering no leathers, faux or animal, effectively biodegrade, perhaps it’s the production impact that’s most worthy of our attention when comparing material + planet relations?

Maybe the most that can be said on the 'natural' front is that leather once came from a living being. That being may have been bred through artificial means, had their offspring taken from them, have been fed a diet inconsistent with their natural requirements, kept in an environment that went against their natural instincts, that itself is kept in an unnaturally arrested development. That being may be kept ‘strong’ with antibiotics that ensure not wellbeing but profit protection, for just as long as is needed for them to reach the next stage of ’product life cycle' that is the life of a farmed animal born to be trucked or shipped to slaughter. Humans have claimed dominion on planet earth, and systematically we are diminishing the wild places + changing the natural balance of our ecosystem with our rapacious appetite for animal derived products.



Data via the Sustainable Apparel Coalition’s Higg Material Sustainability Index tool.

Full disclosure, Emma + I are both vegan + both passionate about seeing animals as individuals not objects.  We don’t believe synthetic leather is the destination, + there is frank recognition that ‘end of life’ challenges exist for both animal leather + synthetic fashion options. High quality leather alternatives become more environmentally friendly when they last for years to come, but recycling of these alternative materials, if they’re not biodegradable, must become far more widespread + accessible. We encourage anyone who is on the fence to consider all angles of the supply chain discussion. If transparency is truly important to you, ask about the animals, the humans, the chemical inputs + the environmental impact of the bags, shoes and clothes you’re buying. There is data and scientific evidence that dispels so much of the marketing buzzwords floating around today.  

There will be of course, a Part 2 to this Part 1, which will take a step even further back into what the ‘raw material’ behind animal leather is, and what the environmental concerns surrounding this are. Cattle drinking water, passing gas, + standing on demolished forest to come then.  Get excited.

Until next time! XO


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