The rise of Advanced Flexible Substrates in material innovation
Many innovative materials are receiving growing attention, particularly in fashion and design. They are often described as “leather alternatives,” but this term can be misleading. These materials are developed in fundamentally different ways and are designed to meet different needs than leather.
In this article, Gianluca Belotti shares his perspective on what Advanced Flexible Substrates (AFS) really are, how they are developed, and why they are an important area of exploration for Stahl.
What are “Advanced Flexible Substrates”?
“Advanced Flexible Substrates” is a less catchy, but more accurate term for what is often referred to as “alternative leather.”
A wide variety of materials fall under this label, including substrates made from mushrooms, cactus, bacterial cellulose, spent brewery grains, lab grown skin, and so on.
Despite the popular name, these materials have nothing to do with leather. In fact, they differ significantly in composition, structure, and origin. Their main selling points tend to be compelling storytelling, animal-free composition, and uniqueness. As a result, they do not truly represent a direct alternative to leather, as they are designed to meet different expectations and applications.
To avoid confusion, we refer to these materials as Advanced Flexible Substrates (AFS).
Why are these materials still marketed as "leather alternatives" despite their physical and chemical differences?
The term “leather alternative” is easily understood by investors and the general public, making it useful for fundraising and market positioning. It suggests a large potential market and aligns with interest in innovative or vegan materials.
However, many companies are gradually moving away from positioning themselves in opposition to leather. Instead, they are refining their value propositions around uniqueness, plantbased raw materials, and sustainability.
At the same time, several companies have narrowed their focus from delivering finished materials to brands to producing the raw substrate. This shift positions the traditional leather value chain as a partner in finishing, rather than a competitor.
How do these substrates differ from traditional materials like leather, synthetics, or coated textiles?
AFS are not a single material type. Their characteristics depend heavily on how they are made and from which raw materials. They can broadly be grouped into three categories:
Plantbased substrates
These substrates often have a structure similar to coated textiles, but incorporate plant biomass into their composition. The biomass is typically derived from agricultural residues or byproducts, such as orange peels or cocoa husks.
Microbebased substrates
These materials are either made entirely from microbial biomass, such as mushrooms, or contain polymers produced by bacteria, such as bacterial cellulose.
Cellbased substrates
These materials are cultivated in laboratory environments from skin cells. While they may resemble leather more closely than other AFS types, their internal structure is still different from conventional leather.
From a construction perspective, some AFS resemble conventional materials, while others are completely different. Many have a high biobased content and a relatively low CO₂ footprint. At the same time, their mechanical performance can be limited, and scalability remains a key challenge.
Why is Stahl exploring Advanced Flexible Substrates?
Market projections differ, but most studies indicate that the AFS market could exceed one hundred million euros by 2030, with strong year-over-year growth. This represents a meaningful opportunity for Stahl.
But there is also another important reason why Stahl is exploring AFS.
This market is indeed an ideal testbed for developing new solutions that can be transferred to other markets and segments. The AFS market is demanding new coating solutions, 100% biobased, and can support medium-term development timelines. Such context is ideal to develop and test innovative and ambitious chemistries that can be transferred to other business units.
What are the main challenges to scaling AFS?
Three major challenges remain:
- Performance
While performance is improving, many AFS still do not meet market expectations in terms of mechanical and chemical properties. - Aesthetics and customization
Options for look, touch, and feel can be limited. For example, embossing can be particularly challenging for some substrates. - Scalability and cost
Many AFS are produced at pilot scale. Moving to commercial production often requires process adaptation or entirely new manufacturing facilities, which significantly impacts pricing.
Why is finishing so important for AFS?
Like all substrates, AFS require finishing. Given their current performance levels, they may benefit even more from finishing than conventional materials.
At the same time, AFS can have very specific compositions and properties. Coatings designed for conventional substrates do not always perform as intended on AFS. This is why Stahl is developing new products and formulations tailored to these materials.
The know-how and solutions being developed today are expected to provide a competitive advantage as the AFS market matures. In the meantime, these innovations can also be transferred to existing business lines to deliver new features and environmental benefits.
What have we learned so far from testing AFS?
Through innovation and collaboration, Stahl is building extensive knowledge around AFS.
This includes understanding the properties and limitations of different substrate types, identifying challenges such as coating adhesion, and assessing which product technologies perform best on specific AFS constructions.
In addition, new fully renewable compounds have been identified that can improve coating performance on AFS and support the development of more sustainable solutions.
How do investors and luxury brands influence AFS development?
AFS companies invest significant effort in engaging luxury brands and investors. Brands provide validation, early applications, and visibility, while investors help bridge the gap between laboratory development and market entry through funding, business guidance, and industry connections.
In some cases, luxury brands also invest directly in AFS companies, further accelerating development.
What makes working on AFS exciting?
Working on materials that do not yet fully exist offers a unique opportunity to rethink value chains. There is potential for regional and circular systems that transform local waste into new materials, produce substrates on demand, and use fully bio‑based finishing formulations.
The result could be innovative materials with new performance characteristics and significantly improved sustainability profiles.
Staying informed in a fast‑moving field
The AFS landscape is relatively complex to follow. Beyond well-known players, many startups operate with limited visibility. Staying informed requires close relationships with material developers, brands, and partners.
AI tools also play a role, helping to find new companies, analyze scientific literature and search news on websites and social media. Even more interestingly, AI can further analyze these sources over time and track the evolution of specific companies in terms of their technology, strategy, communication, and market sentiment.
Looking ahead
Like any emerging market, Advanced Flexible Substrates will continue to evolve rapidly. New materials, investments, and collaborations will emerge, while not every concept will succeed.
For Stahl, the focus is on cutting through the noise to identify meaningful developments and opportunities where finishing technologies can create real value. By building knowledge and experience now, Stahl is preparing for future opportunities in AFS while strengthening innovation across existing markets.
About the author:
Gianluca Belotti is Business Leader Advanced Flexible Substrates at Stahl. In this role, he analyzes and shapes the AFS landscape, bridging material innovation, sustainability, and finishing technologies. Gianluca tracks new industry players, technologies, production methods, and collaborations, turning Advanced Flexible Substrate developments into opportunities for Stahl and partners.