Let’s talk about “leather”, comparing apples and pears…

In the previous article, we briefly discussed the meaning of different concepts within the sustainability trend, from eco-friendly to ethical fashion and everything in between. Back then, we already promised more would follow on the subject and here we are!

Over the past few years, the use and value of leather has been put to the challenge: is the material sustainable enough? Should there be more attention to animal suffering? What substitutes can be used to create a leather-like result? All of these are great questions that stimulate a more diverse and sustainable industry. As of today, leather is still one of the front-running materials used in everyday fashion. However, far from all shoes are made from animal skin and the future might entail something entirely different.

Overall, three types of leather can be distinguished. The original leather, processed animal skin, is the most common one. Cattle and calves, goats, lambs and sheep, reptiles and wild animals are valued for their skin. Because of its unique properties, leather is extremely suitable for shoemaking. Think of the strength of the material, the flexibility, the feeling and look. These do not only make a pair of boots comfortable to walk in, but also enhance their beauty.On the other hand, tanning is a polluting process. Cows cultivated for their skin produce a great amount of carbon dioxide emission. Similarly, every step of the tanning process is executed in different factories around the world, allowing emission to grow even more due to transport. Therefore, the sustainability trend within the fashion industry has been searching for alternatives to the use of animal skin. Different materials, product processes and treatments are conducted to find the perfect, sustainable alternative. So far, two streams of vegan “leather” are to be distinguished:

Firstly, synthetic “leathers” or artificial “leathers”, are made from fossil fuels. In this sense, these man-made leathers are vegan, since no animal properties are incorporated in the making of the materials. However, these materials are far from sustainable. Emission, as a result of oil gain, further damages our planet. Also, as the production costs maintain low, prices for a pair of shoes are equally low. Ultimately, this vicious circle enhances overconsumption and overproduction.

The second alternative is posed by the so-called bio-based and “vegan leathers”. They hold some of the properties of original leather and synthetic leather combined. Some of the great advantages of these materials are the fact that no animal was harmed in the process, as they are derived from fruits, plants and fungi. The leathers are often biodegradable and produce far less emission than original and synthetic “leather”. For instance, Mycelium, a fungus grown directly into shape, minimizes waste.

All these newly introduced leathers have different properties which make them unique. Some are better-looking than others, and some are stronger or have a better longevity. When considering different types of vegan leathers, it is important to consider the following properties of a material:

• Appearances
• Thickness
• Resistance
• Strength
• Water vapor permeability and absorption

Ultimately, these 5 properties will determine the quality of the shoe.

In this sense, vegan and bio-based leathers are to be divided into three sub-divisions: the naturally grown animal-free materials, such as Kombucha and Mycelium (or MuSkin), leather made from agricultural waste-derived products, such as apples (Appleskin), grain (Vegea) and cactus leaves (Desserto), and, through non-woven natural fibers made from pineapple (Piñatex). Different from Piñatex, which is a by-product of the pineapple production, the waste-derived materials stem from leftover peels and waste. All form great, biodegradable and non-poisonous alternatives to leather.

Touch & feel

Between these sub-groups and materials, different properties determine the likeliness of the performance. The look of the material may seem inferior to the strength and flexibility but proves important when shoes actually hit the shelves. Who wants to buy shoes that do not look pretty? The waste-derived materials Appleskin and Vegea have a soft feel to them but are simultaneously artificially-looking. Desserto, on the other hand, feels rather rough and has in that sense little resemblance to actual leather. Only MuSkin has a suede leather feel to it, giving it far more resemblance to the original product compared to all other vegan options.

Thickness

Similarly, the thickness of each product determines how well the material is suitable for shoe-production. The thicker the material the more difficult it becomes to shape it into a pair of shoes. On the other hand, if the material is too thin, it easily tears. Desserto, Appleskin, Vegea and Piñatex have a thickness similar to leather, which makes these materials suitable for the production of shoes, bags and other leather products. MuSkin, however, is rather thick, while Kombucha, is too thin.

Bendability or resistance

The bendability of shoes is of great importance to the foot settlement and therefore the comfort. Piñatex is the only material that is bendable, just like leather. Other materials, such as MuSkin and Desserto are not flexible, allowing the shoe to easily tear or crack.

Strength

The most important properties for shoe materials are the tear and tensile strength. The strength is important for the longevity of the shoe. A pair of boots has to endure much on a daily basis: we walk to the grocery store, run to catch the bus and put our shoes on and off every time we enter or leave the house. Therefore, they need to be strong and able to withstand our movements. Overall, the strength of the waste-derived materials is better in comparison to MuSkin or Piñatex. However, none of the vegan alternatives has a strength that has close resemblance to leather. In this sense, the vegan options are not as sustainable as actual leather.

Water vapor permeability and absorption

The water vapor permeability and absorption varies tremendously depending on the leather type. Leather made from animal skin has a very high rate of absorption and a lesser rate of permeability. This allows the shoes to maintain dry and breathe. MuSkin and Kombucha have a 100% permeability rate, while the absorption is far smaller. This means that the material absorbs little water but is able to transport sweat and smells. Therefore, the material is not fully suitable to withstand wet environments but will survive a little rain now and then. Waste-derived leathers, on the other hand, have little absorption and even smaller permeability, making the materials unsuitable for rainy weather. Similarly, Piñatex has too little properties for water vapor absorption and permeability.

 All in all, leather is and might always be the most suitable material for shoe-making. These days, alternatives to the high emission rates of tanning are reviewed and applied. Here at OPUS, for instance, we work with different tanners producing all sorts of leather. From LITE leather (Low Impact on The Environment), produced by Vietnamese tanner ISA Tantec, to completely vegan leathers made from raw, natural materials or recycled products.

Similarly, recycled PET, polyester and rubber are incorporated nowadays to reduce waste. These provide solid alternatives for the liner, laces and soles. However, practicing and researching alternatives that do not include animal harm are part of the future of tanning. Every day new materials are found, which bring us closer to a sustainable industry.