The Sustainability of Leather
Is leather a sustainable material? It can be. When leather is sourced, processed, and disposed of responsibly, leather can be a very sustainable material. It has an extremely long product life and can decompose without harmful effects. If your leather jacket was responsibly produced, it can last you a lifetime and then decompose without any harmful effects.
Unfortunately, to increase speed and profits, the vast majority of the leather industry employs a number of extremely harmful methods. These methods expose workers, communities in leather processing areas, animals, and consumers to high levels of extremely hazardous materials. They also produce a staggering amount of hazardous waste that is often dumped without proper treatment or with regulated standards. Fortunately, there are sustainable and ethical alternatives in the leather world. We’ll point those options out for you, but first, let’s look at what goes in to producing a leather bag, boot, or belt.
Leather Treatment & Stabilization
Tanning is a process that stabilizes and preserves leather, so as to prevent it from decomposing or stiffening into un unusable material. The processing that takes a hide from the source animal to workable leather begins a step before tanning, with what’s known collectively as beamhouse operations.
Beamhouse Operations [ Hide Preparation ]
Skins are cured and packed with salt to keep them from putrefying between the point of slaughter and beamhouse processing. The beamhouse process begins with cleaning the hide to remove any present meat, fat, and hair. Unfortunately, usually during this stage, lime pastes, sodium sulfide, ammonium salts, and bleach are routinely used. This step accounts for 80-90% of the pollution created by the leather industry. It produces noxious gases and solid waste sludge including hydrogen sulfide as well as lime and ammonium salts. Keep in mind, this isn’t the green lime garnishing your drink (cheers) but a caustic alkali Ca(OH)2. The hide is then sometimes pickled with salt and sulfuric acid. Once the hide has been cleaned, it is considered a rawhide.
The rawhide is then tanned in a bath. Tanning is a process that softens the rawhide while preserving it, so as to keep it from decomposing. The difference between a rawhide and a tanned hide are evident when they are exposed to water and heat. A rawhide hardens when exposed to heat and decomposes after exposure to moisture. A tanned hide maintains its flexibility when exposed to heat and does not putrefy even after exposure to moisture.
Chrome Tanning – Chrome Sulfate
Chrome tanning processes are used by an estimated 90% of the world’s tanneries. Chromium is cheap and efficient. It softens the leather in just a few hours. It has been widely used since the 1890s. In many countries where leather is produced and processed there are not strong environmental protections in place. India, China, and Bangladesh are some of the largest producers of the world’s leather and have lenient to no standards enforced. The leather industry is a multi-billion dollar industry (some estimates put the number at $100 billion) that brings in critical tax revenue for many countries. These countries unfortunately see these much needed health and environment regulations as obstructions that may jeopardize their revenue.
Chrome Related Pollution & Hazards
The hazardous waste water produced in the chrome tanning process is heavy with chromium and other toxic compounds including lead and arsenic. It is dumped, more often than not untreated, into rivers and waterways where it directly impacts communities and wildlife in the area. Exposure is hazardous to not only workers but entire ecosystems in the surrounding area. Communities in many of these areas, along the Ganges in India for example, use these polluted waterways for drinking, bathing, and farming. Chromium can cause a host of skin problems when encountered without protection. It can cause cracked, dry, and scaled skin. It also causes what are known as “chrome holes”, which are corrosive ulcers that are stubborn heal.
These tanning factories also create huge amounts of air pollution. Further, about 70% of the mass of a virgin hide ends up as solid waste, not before being treated with chemicals mind you. Hence the major sludge production mentioned earlier. The solid waste consists of about 75% leather shavings, which can easily become airborne and quickly spread. This dust contains an especially dangerous form of chromium which has already bonded with a protein. This form is more readily metabolized and can enter the body through inhalation, ingestion, as well as direct cutaneous contact.
Many plants and animals need a minute amount of chromium to help regulate their metabolic functions. However, the amount of chromium used for treating leather is on another scale entirely. In such large quantity as is released through the tanning process, chromium is extremely hazardous. In abundance, chromium causes cancers, respiratory problems, infertility, birth defects, and developmental problems in animals big and small.
Vegetable Tanning – A Sustainable Alternative
Instead of using chromium, the process of vegetable tanning uses traditional leather processing methods that can cut out toxins entirely. Natural tanning requires rawhides to be soaked for several weeks in baths with tannins derived from natural sources like tree bark and fruits. The tannins coat the collagen proteins in the hide with a protective layer, rendering them less prone to bacteria growth and more water resistant. This also increases flexibility in the hide.
Vegetable tanning is a longer process that is most definitely worth it. A leather bag or pair of boots can last you a lifetime and even be passed down generation to generation. If it takes a few more weeks to be sustainably derived, then so be it.
Wet White Tanning
Wet white tanning is an alternative to chromium tanning that uses a combination of synthetic tannins, vegetable tannins, glutaraldehydes, and minerals including aluminum and zirconium. The resulting wastewater, leather shavings, and leather product hold no reactive tanning agents. This method of tanning uses the same equipment that chrome tanneries are using and have already invested in.
Interestingly enough, the automotive industry has been instrumental in the drive for more sustainable leather options. The automotive industry is the largest consumer of chrome-free leather. This was spurred by regulations set by the EU in 2000 to increase recycling and proper disposal of abandoned vehicles. Chrome-free leather is biodegradable and much easier to handle for disposal. In fact, wet white tanned leather can reach half of its original weight with 56 days when being decomposed.
After tanning, the leather is thinned, through a process known as crusting. Crusting releases a significant amount of dust and solid waste. After crusting, the hide is then sometimes tanned again, colored, lubricated, softened, and shaped.
Other Leather Processing Dangers
Raw hides can be an incubator for anthrax. Posing yet another airborne risk for those working in and near tanning factories. Additionally, with few workplace regulations in many of these processing factories, workers are subject to a number of dangers. These include improper handling of toxic chemicals, inadequate training and access to safe workplace attire, and improper disposal of waste which can quickly lead to slippery and precarious work surfaces.
The Animal Element
Unfortunately, since so much of the leather industry is unregulated, the animals at the source of the $100 billion dollar industry are no exception to mistreatment. Certifications of leather to ensure ethical animal husbandry can be tricky to navigate. Let’s take a look at a few of them.
IVN Natural Leather Standard
The IVN Natural Leather standard encompasses environmental impact of the leather, animal welfare, and social criteria of the leather at every point of processing. All materials used in processing are tested for toxicity and biodegradability. That then prohibits the use of chromium, glyoxal, and short-chain chlorinated paraffins. Hides from endangered species are prohibited. The place of slaughter must be known and documented. Environmental and social policies must be adhered to in manufacturing sites. On site inspections are performed as well as residue testing of products to ensure these standards are met. These standards are similar to those set by the Global Organic Textile Standard (GOTS) for fiber textiles. Unfortunately, the GOTS neglects to include leather as a textile and does not offer a route for leather certification.
The Rainforest Alliance
The Rainforest Alliance certifies ranches that raise animals for leather production. These ranches are certified with sustainable farming standards that address animal welfare, prevention of deforestation, conservation of biodiversity, human wellbeing, conservation of natural resources, and respect to the land on which indigenous people reside. Unfortunately, the Rainforest Alliance certification stops with slaughter.
Most imitation manmade leather on the market is not a sustainable or healthy choice. Known by many names, PU leather, pleather, leatherette, vegan leather, faux leather, is another plastic synthetic material. Most pleather is made from polyurethane, polyester, and polyvinyl chloride. These materials, derived from coal, natural gas, and oil, have a high impact on the environment in production, during product life, and after being discarded. Unlike natural leather, these manmade leathers will not decompose for hundreds of years. These materials are also not breathable and are more prone to bacteria growth.
Cork as a Leather Alternative
Cork is proving to be a sustainable leather alternative for many products. Products made with cork are comparable to leather in terms of longevity. Think of a cork in a wine bottle – they’re trusted to stand the test of time. Cork fabric is also a great vegan alternative. It is naturally produced, can be sustainably harvested, water repellant, fire retardant, scratch proof, and stain resistant. Compared to leather that can be somewhat intensive to clean, oil, and care for, cork fabric can be washed simply with soap and water. Cork is also recyclable.
Cork grows as a tissue layer in bark on cork oak trees (Quercus suber). The trees can live for 200 years and are not cut down when the bark is harvested. The bark is harvested on a well kept schedule that does not harm the tree.
Cork does not, however, have quite the same look as leather. If leather is what you seek, read on.
MuSkin is a material extracted from mushroom cap skins. The mushroom, Phellinus ellipsoideus, is native to subtropical forests. MuSkin is not waterproof, but can be treated with an eco friendly wax to achieve this property. Alone, MuSkin does not have great mechanical strength, but can be paired with something structurally stronger. It is breathable, pliable, and is a 100% biodegradable material. Unfortunately at this point, MuSkin does not appear to be widely used, so longevity and wearer satisfaction are hard to judge.
Yea! We’re wrinkling our noses too. But unfurl them! There is no smell. Fish skins collected as a by product from the commercial fishing industry are dried, deodorized, and dyed with vegetable dye. Since fish skins are usually smaller than most hides, they’re used for smaller products like shoes and accessories. Unfortunately, many manufacturers use highly toxic chemicals to clean and deodorize the hides of the fish.
Modern Meadow’s Innovation to Grow Leather
Modern Meadow, a bioengineering group with a mission to take the ‘animal’ out of ‘animal products’, has developed a system to biofabricate leather. By harvesting a strain of yeast that produces collagen, Modern Meadow has eliminated the need for the beamhouse operations all together. In a sense, traditional tanning removes everything but the collagen protein of a hide (remember how much solid waste is produced?). Instead of stripping everything away from a hide, Modern Meadow is building up to a hide. They encourage the nanofibers created by collagen to form into sheets of leather. The nanofibers are highly tunable, allowing them to take command of properties like thickness and stretchiness.
By skipping the Beamhouse processing, Modern Meadow cuts out a hugely polluting phase in leather processing. Still in the research and development stages, Modern Meadow has not yet announced tanning and finishing methods for their products. We’re very excited to see this leather alternative develop further.
What To Do
As always, buy less, and buy better. In this case, buying second hand, vintage, and vegetable tanned or wet white tanned leather are the most sustainable options (the first two being the most). There are a number of awesome designers reclaiming leather and upcycling the material into some beautiful collections. The Sway, a leather designer based in New York City, is one of our favorite examples.