Questions about copies
25/06/2025
What is the full extent of FILK’s work with the leather industry today? Please describe the different activities you engage in on behalf of the industry, in Germany and beyond.
We are, historically, a leather institute but we extended this some time ago to synthetics too. People know this. So today we work in both fields. In leather we work especially on material science and chemical principles for leather manufacturing, including tanning principles and retanning principles. Connected to this, we work on the use of by- products from the tanning industry in, for example, cosmetics, medical or food applications. We also work on polymer treatments for the manufacture of synthetic alternatives, including materials that are plant-based and ones that some people call ‘next-generation’. In the end, they are all flexible materials composed of different layers and which are used for automotive, upholstery and fashion.
What is your professional background? How did you come to work at FILK? What are the different roles you have held at the institute?
From a professional background I am a biologist. I studied biology and process engineering at Freiburg in the south of Germany, and at Freiberg near Dresden, then I did my PhD in polymer chemistry at Dresden. After that, I did what we call a habilitation, a post-doctoral research qualification, in process engineering in Berlin. My first role at FILK was to set up a small working group focusing on the use of by-products of the tanning industry, especially in the field of medical applications. This increased greatly and in the end I was responsible for the whole field of collagen treatment, for leather as well as for medical and food applications. Today I am the CEO and responsible for all scientific fields at FILK including synthetics.
We often complain of a lack of unity and leadership in the global leather industry, but it seems possible to argue that, thanks to IULTCS, to FILK and a number of other organisations, that there is a high level of common purpose and joint working among leather chemists and technologists. If this is true, why is it true? How has your community been able to achieve this to a greater extent than other groups?
I think the levels of competition 20 or 25 years ago were very high. This is my opinion, based on what I observed and learned at that time. Today, the sector has decreased in size and companies and organisations have learned that they have to work together. They have learned this because of outside pressure. But we have also realised the need to learn from each other. Of course, chemicals manufacturers and even institutes like ours still have to be competitive. We, for example, carry out testing and we have to compete with other testing laboratories. But we can approach ways of finding the best use for animal hides with a common mindset; there is a common purpose and we can work together. We have to do this more intensively, but it is becoming better.
How would you sum up the main findings of FILK’s 2021 paper comparing the technical performance of leather with that of alternative materials?
In the case of leather, what we have is a material that has universality. What I mean is that it is very strong in a number of different areas. It has qualities that make it suitable for use as, for example, an upholstery material or as a fashion material. It depends on the final application, of course. If we have applications in which we don’t need the very strong performance of leather, because there is a less demanding environment, then it is not necessary to use leather. As the study shows, we do not see this universality in alternative materials. The alternatives have some aspects that are sometimes better and, usually, others that are much worse. This universality, its ability to perform so well against all the different parameters, may be the unique selling point of leather. In my opinion, this is correlated with the principle that leather is made from skin. Skin has a biological function, which is to be stable, to be elastic, to have good abrasion behaviour, good breathability and so on. We preserve these qualities when we make leather from hides and skins. There have been many attempts to copy this with alternative materials, but up to now none of these has worked.
What feedback have you had from the manufacturers of the alternative materials that you tested?
They know that they don’t have the universality, the performance across the board. But I repeat: it depends on the application. A brand will use alternative materials in fashion if it wants to be vegan, of course. That would not be possible with leather. That’s one aspect. At the same time, leather is not as stable in wet conditions as some of the alternatives. It absorbs water too easily and you may decide you need rubber boots instead to go outside in the rain. It’s always important to consider the application when we talk about these alternative materials.
You said on ZDF television in 2023 that adding words such as ‘apple’, ‘pineapple’, ‘cactus’ or ‘mushroom’ to the names of alternative materials adds nothing to their performance. Have you come across any exceptions?
We observe that there are three groups of these materials. One group is the synthetic materials that present themselves as being similar to leather, which are just filled up with biogenic materials. One example is apple powder. Things like this are biogenic fillers that take the place of inorganic materials. The second group is newer materials like for example the pineapple material. This has a fibre construction and is bonded together with synthetic glue. Compared to leather, it is a completely different material. The third group is lab-grown materials. I’m not sure whether these are a possible alternative or not. Up to now, I haven’t seen any of these lab-grown materials achieve the volume or, of course, the price for them to be competitive with leather. The fact is that we have no exact copy of leather to date. I am not sure if we ever will have.
The practice of using plant names continues. In May 2025, World Leather received a press release from a handbag brand that uses a plant-based material. The press release includes the claim that this material has a carbon footprint that is “ten times lower than leather’s”. How should the leather industry react to claims like this?
We learned during the thirteenth Freiberg Leather Days event, also in May, that there are a couple of different possibilities for calculating carbon footprint. We can have a very bad carbon footprint if we have high numbers of animals kept in bad conditions. We learned as well that we can sequester carbon if we have good management of herds as part of the biogenic cycle, in combination with plants and other options. So we can have a broad range of carbon footprints. In the end, we have to do lifecycle analysis (LCA) studies and we have to look at the whole chain. And the same for alternative materials. To my knowledge, up to now, there has been no complete LCA for any of the industrially produced materials that some people compare to leather. And this is the challenge, I think. We are not allowed to compare apples with pears, of course, but we have to think about the right way to compare different materials if they are used in the same applications. A second point is that it is really important to calculate the whole LCA and not only parts of it. Just the production part is not enough. We have to include raw materials, end-of-life processes and the length of time the material is in use. Durability is very important. To argue (as the European Commission’s technical secretariat for calculating product environmental footprint category rules for shoes appears to do) that a product can be called long- lasting if it is in use for just six months is not reality for leather. I think the challenge is to find methods to measure and calculate these LCAs in a way that is nearer to the reality.
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