Does start-up Reselo have the answer to fossil-free rubber? The company's material is already used for shoe soles – and together with a manufacturer it is now being adapted for tyre production, which accounts for 70% of the world's rubber consumption.
"The material is made entirely from birch bark and can be incorporated into existing production processes," says Josefin Larsson, CPO at Reselo.
Rubber is everywhere – in car tyres, shoes, electronics and medical devices. But today's rubber, both natural and synthetic, faces major climate challenges. Deforestation, fossil fuel dependency and microplastic emissions make the need for sustainable alternatives urgent.
Underutilised by-products from the forest industry
That's where Swedish start-up Reselo comes in. They have developed a fossil-free rubber based on birch bark – a previously under-utilised forestry by-product that can now be given a new and long life in a wide range of products.
The material is vulcanisable, meaning it can be used in everything from car tyres to shoe soles to automotive components, and is compatible with all common rubber polymers for compounding.
It all started in 2018 at the KTH Royal Institute of Technology in Stockholm, where Thomas Baumgarten, originally from Germany, was researching the valorisation of birch bark. He developed a process to produce the new biomaterial, which is now known as Reselo Rubber.
Reselo was founded in December 2020, after Thomas Baumgarten met Josefin Larsson and Henrik Otendal during the Startup Climate Action Challenge.
"It quickly became clear that the material could be of great use in replacing a largely fossil-based rubber production, and therefore the step into industry and the startup world was obvious," says Josefin Larsson.
Partners and collaborations in various industries
Since then, things have moved fast. Today, Reselo has ongoing and future collaborations with partners in various industries, from forestry to fashion.
"We have shown that the market is ready for a new rubber material and that the process is commercially viable on a large scale. Right now, we're focusing on shoes and soles – both consumers and brands are demanding solutions that are truly sustainable, and change is happening fast," says Josefin Larsson.
There is already a prototype sole in the handmade shoes from Skråmträsk, which are produced on a small scale in Västerbotten. Reselo hopes that soles made from its material will soon be found in the products of larger shoe companies.
But it is in the automotive industry that the material could make the biggest difference.
Reselo has signed a development agreement with Finnish tyre giant Nokian Tyres, which aims to use 50% renewable or recycled raw materials in its tyres by 2030. Together with Nokian Tyres, the company is now further developing the material to adapt it for tyre production.
"In the long term, this is where we can have the greatest positive impact, as 70% of the world's rubber is now used in tyres," says Josefin Larsson.
RISE was instrumental in the early stages of demonstrating the technical feasibility of our process.
Essential support to demonstrate technical feasibility
But there have been challenges along the way – not least in terms of resources such as analytical equipment and development tools.
This is where RISE has played an important role.
"RISE was crucial in the early stages to demonstrate the technical feasibility of our process. Third-party verification has been very valuable, as it directly creates confidence among the various stakeholders," says Thomas Baumgarten, CTO at Reselo.
"This in turn has made it easier to secure public and private funding and to initiate partnerships with industry. In addition, RISE has produced the first kilos of our new material, enabling us to carry out market testing and start our product development.
RISE has also helped Reselo assess the commercial potential of the process through a techno-economic analysis.
"RISE's equipment and ability to perform development scale experiments, combined with their expertise, has been extremely valuable to us. This is the first step towards a marketable product, and without such a partner at an early stage we would not have been able to take the big steps we have already taken," says Josefin Larsson.
For RISE, Reselo is a dream case.
"Reselo is a very interesting customer for RISE – a new technology with the potential to really change the world. This is the kind of collaboration we value, where it's not just about a customer relationship, but about supporting an innovation that can have a big impact," says Jonna Almqvist, Project Manager at RISE.
Vulcanisation behind everything from gaskets to tyres
Vulcanisation is a chemical process that improves the mechanical properties of a material, such as elasticity and strength. It involves adding a hardener and then subjecting the material to heat and pressure, making it more durable and less sensitive to temperature changes.
It has enabled natural and synthetic fossil-based rubbers to be used in a wide range of products, from shoe soles to industrial seals and car tyres.
