Biodegradable Leather

Is leather biodegradable?

Leather is one of man’s earliest and most useful inventions. It is durable material and the hides that are being used are sustainable in itself, as it is a byproduct from the meat industry.

Society asks for leather that is not just durable, but also biodegradable. But, what does that mean? What is the definition of biodegradable leather? When is leather biodegradable? What is the difference between composting and biodegradation?

Important questions, to talk about and understand. Leather and leather goods definitely have the potential to be biodegradable. It depends, among other, on the chemicals being used.

Any leather can be composted but the speed of degradation and environmental impact depends on
the tanning chemistry used.

Facts about leather and biodegradability

A natural and unprocessed hide is biodegradable.  Leather is made from a hide or skin, a naturally biodegradable material and a byproduct of the meat industry. To use a hide or a skin for a leather good, for example for a car seat or a handbag, it needs to be processed. This process is called the tanning process. The tanning process changes the chemistry inside the leather fibers to make it more difficult for the enzymes from bacteria and fungi to break them down. This also changes the biodegradability of the material.

Figure 1: Hide and chemicals combine into leather

Leather is a durable material. A leather product stands the test of time – and better yet – it develops a gorgeous finish over time. Durability is one of the key features of leather.

Leather can be a biodegradable material.  Processed leather can be composted but the environmental impact and the biodegradability of the leather depends, among others, on the tanning chemistry being used. Not all leather is biodegradable.

The importance of Biodegradable Leather

Ocean plastic pollution, or the “Plastic Soup” as we know it, has highlighted just how important it is that materials can degrade back into the natural environment. The end-of-life of a leather article is therefor a vital topic to understand and to talk about. It is also a subject that leather manufacturers and fashion houses are interested in because consumers are increasingly demanding eco-friendly leather. The leather industry is taking the responsibility for the next generation to drive more sustainability in the leather value chain. Biodegradability is an important part in this matter.

Stages of biodegradation

Biodegradation of a material such as leather undergoes three different stages.

1^st stage:

Biodeterioration, e.g., black spots on bananas – surface breakdown

2^ndstage:

Biodisintegration e.g., the banana becomes soft due to bacterial breakdown, material breaks into smaller pieces

3^rd stage:

Bioassimilation e.g., the banana is broken into compost mass, taken into biomass) – also called ultimate biodegradability.

During the first two stages, leather breaks down into smaller components. In the third stage, these components are assimilated as nutrients by microorganisms. Materials that remain at the 1^st or 2^nd stage are not ultimately biodegradable and persist in the environment, typically as small pieces or scraps.

Compostability is a special case of biodegradability. Compostability is the capacity of a material to be biodegraded into compost and it relates to the first two stages of biodegradation. It requires specific environmental conditions where ecological toxicity criteria are applicable.

When a material passes through all three stages of biodegradability then it is fully taken up as new biomass and close the material cycle.

End-of-life environments

The end-of-life (bio)degradation of materials depends on the environmental conditions: wet or humid, with or without air, hot or cold.

Leather and the articles made from it at the end of their life can be found in environments such as landfills, effluent treatment plants, and composting units or littered in nature. In Figure 2, these environments are compared and the common tests used to simulate the different environments are shown.

Figure 2 The range of end-of-life environments and the test used to similate them

This figure is taken from the whitepaper ‘Biodegradability and disintegration of leather‘. A scientific and well founded report.

Download the whitepaper (free)

Test result: biodisintegration of leather

We have tested and compared (a) zeolite tanned leather with (b) conventional tanned leather. Zeo White leather will rapidly biodisintegrate into fine pieces if purposely or accidentally placed into the environment. The biodisintegration of Zeo White under industrial composting conditions gave a proper compost within 15 days. The test demonstrates that the tannage stabilises the leather for in-use, but in the biosphere, the microbes can easily access and use enzymes to disassemble the collagen protein structure.

Read more

How is leather made?

To understand the biodegrability, but also the sustainability of leather, it helps to know about the leather manufacturing process.

There are many different types of leather and therefore many variants on the manufacturing process and also various ways to describe. This article and infographic explains the five steps of the leather production cycle.

The leather making process: step by step