Future Net Zero: Are alternative leather materials as green and sustainable as their names imply? Recent research shows that many should in fact come with a sustainability health warning

Hardly a week goes by without a leading fashion brand announcing that it’s bringing out new products using a vegan or eco-leather alternative.

Labels are increasingly catering for environmentally conscious consumers who rightly or wrongly see natural leather as a problem.

But, are these alternative materials as green and sustainable as their names imply? Recent research shows that many should in fact come with a sustainability health warning.

The research was conducted by the widely respected FILK Freiburg Institute, which looked at the construction and technical performance of leather, artificial leather and other alternatives.

The German-based scientists looked at a number of materials and analysed their chemical compositions and their strengths and weaknesses compared with animal-based leather.

Surprising finds

What they found in some of the newer materials was highly surprising. More of that in a minute, but first the less surprising.

The most commonly used material that is cited as vegan leather, leatherette or faux leather is actually made from polyurethane (PU), polyvinyl chloride (PVC), or polyamide microfiber. In other words, plastic. PVC and PU leather is made from oil and is non-biodegradable. These materials leak toxic chemicals into the ground when placed in landfills, and emit toxic gasses when burned in an incinerator.

Understandably, the textile industry has been on the search for a more sustainable alternative to PU or PVC leather. In recent years, the focus has been on plant-based materials and it is these that FILK took a close look at.

In general, it found that most rely on backings to provide the strength and durability that is inherent in natural leather. However, these backings are far from sustainable and in many cases are plastic, being made from PU or PVC.

More worryingly, when FILK conducted tests for hazardous substances, it found restricted substances in samples of the following materials:

• Desserto
• Appleskin
• Vegea
• Pinatex

The analysis found considerable amounts of dimethylformamide (DMFa) and toluene and traces of N,N-dimethylacetamide. In Appleskin, butanone oxime and traces of DMFa were detected. Desserto contained the five restricted substances butanone oxime, toluene, free isocyanate, folpet (an organic pesticide), and traces of the plasticizer Diisobutyl phthalate (DIBP). Toluene was detected in the sample of Vegea and DIBP in that of Pinatex.

A toxic sandwich?

Natural leather has many uses; shoes, gloves, jackets, car seats and furniture to name just a few. The most important mechanical properties needed are tensile strength and tear resistance.

In order to show anything close to the mechanical stability of natural leather, the alternatives depend on supporting fabrics to form a sort of sandwich. The most commonly used material is polyester, which is a synthetic fibre manufactured, like PVC and PU, from oil/petroleum. As a result, it is non-biodegradable. In addition, producing polyester takes twice as much energy as that needed to make cotton.

Another problem with polyester is microplastic pollution. It’s estimated that nearly 2,000 tiny fibres are released every time a polyester garment is washed and these end up in our rivers, seas and oceans. Environmentalists see polyester as such a problem that they even advise against the use of recycled polyester.

FILK research showed that Desserto and Appleskin both used knitted or woven polyester for support. They also discovered that Teak Leaf is another coated textile; its textile support is provided by two now woven layers – one made from cellulose and the other from polyester.

The problem with pineapples

Pinatex is a leather alternative made from pineapple leaves, a by-product from growing the tropical fruit. The business behind Pinatex, Ananas Anam, sources its leaves directly from farmers in the Philippines. However, if pineapple leather becomes more widespread consumers would be advised to ask where the raw material has been grown.

In some places, growing pineapples relies on heavy use of chemical pesticides and this is causing problems in countries like Costa Rica, where the chemicals have contaminated water supplies.

Leather industry improving its game

In response to environmental concerns, leather producers are working to make the tanning business more sustainable. Many tanneries are now audited by the Leather Working Group, which is an initiative backed by suppliers, manufacturers and brands.

Tanneries are rated on their energy and water use, emissions and chemical input, as well as the traceability of their supply chain.

The recently launched Sustainable Leather Foundation aims to improve the industry through education and best practice, while providing consumers with factual information about leather, so they can have confidence when they buy. Its founding partners include Mulberry, Qualus and Deckers Brands.

Qualus uses patented Sfere technology to improve the sustainability of the tanning and retanning process. Small polymer spheroids partially replace water as the delivery mechanism and drive chemicals deeper and more uniformly into the hide, resulting in a more consistent product with smaller volumes of chemicals. Results show that water use is cut by up to 40% and chemical use by 25%.

Saving water and reducing or changing the chemicals used in the leather industry is at the forefront of other significant developments.  One promising technology is Zeology from Nera. It offers a sustainable alternative to existing tanning agents by using a chemical formula that is free of chrome, heavy metals and aldehyde.

The footwear brand, Ecco, has developed a process called DriTan, which it says saves 20 litres of water per hide in the tanning process. It also cuts the amount of chrome needed which results in less effluent.

The German chemicals company, LANXESS, has developed a process called ‘Resource-efficient manufacturing of leather chemicals” (ReeL), which recycles shavings in the tannery on site. The shavings are used to produce X-Biomer retanning agents automatically within a modular facility. This new technology eliminates the cost of transporting materials for off-site recycling or disposal.

A lot of research has gone into reducing the volumes of water used in leather tanning. One promising solution comes from China-based, BIOSK Chemicals. It has developed technology to store wastewater from each stage of the process so that it can be used again.

Looking at these developments it’s clear leather will go a long way to answering its critics over the issue of environmental impact in the next few years.  Of course, consumers opposed to the use of real leather because it is an animal by-product won’t be persuaded by anything the industry does. However, those who may have turned their backs on leather believing vegan alternatives are the sustainable choice may be surprised by how the choice is more complex than it first appears.

Paul Curran, Future Net Zero