CCB Magazine

Lignin is the second most abundant biopolymer on earth after cellulose. It can be extracted from black liquor and gives trees their strength. To this day, it is almost exclusively burned - to generate electricity. Two designers from Berlin thought there was more to it than that and launched the BLACK LIQUOR project. Their goal: to replace petroleum-based plastics with biodegradable lignin-based products. Can this work? We talked to project initiator Esther Kaya Stögerer about it.
 

Text Boris Messing

It's a sunny May day in Berlin when we meet in front of the back entrance of the Museum of Decorative Arts for a conversation. Esther Kaya Stögerer, dressed all in black, arrives on her bicycle from Friedrichshain and greets me through the mask with a good-humored "hello". A slight Austrian accent resonates in her voice. Styria, as she immediately reveals to me. Here at the Museum of Decorative Arts, she and Jannis Kempkens will be exhibiting their BLACK LIQUOR project, which they have been researching for over a year.

We walk past the gatekeeper through dimmed, plain rooms where this and that is standing around, through the bowels of the museum that you don't normally get to see. The front doors are still closed, but soon they will be open to the public - by means of a time slot ticket and corona test. As part of the "Design Lab" series, an exhibition will be on display there from mid-June to the end of August that deals with the topic of design and the circular economy. BLACK LIQUOR is one project of them. It was awarded the "Form Progress Award" in 2020 and was created in a cooperation with the greenlab of the Kunsthochschule Weißensee and the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut (WKI) in Braunschweig. It was supported by the Fraunhofer network "Science, Art and Design".

Photo: Esther Kaya Stögerer, Jannis Kempkens

We arrive in the exhibition space, which is not yet fully prepared; sunbeams flood from outside through the large windows and bathe everything in a soft light. One of the curators is busily tidying up and makes us two stools out of cardboard boxes, with which we sit down next to the BLACK LIQUOR exhibition area. There are already samples of their product, plates and petri dishes full of fibers, powders, coffee grounds - but we'll get to that in a moment. Speaking sounds muffled through the masks, smiles are made with the eyes.

Esther explains how the project came about in the first place. She met Jannis during the "foundation year" at the Kunsthochschule Weißensee, where they were also both active for a time in the General Student Committee. Before that, she says, she worked with two designers on another project, which eventually gave her the idea for BLACK LIQUOR. That project was about what actually happens to old wood-based materials like MDF or particleboard when they have to be disposed of. These wood-based materials are bonded by synthetic binders and therefore often have to be disposed of as hazardous waste. This is how Esther indirectly came across lignin, because lignin is nothing other than a natural binder. After cellulose, which is used to make paper, it is the second most abundant biopolymer on earth. It gives trees and other plant tissues compressive strength and stability. When a tree dies, it rots in the forest by being decomposed by fungi.

BLACK LIQUOR, says Esther Kaya Stögerer, has the potential to replace environmentally harmful plastics. Lignin-based products could rot in the forest and thus flow back into the natural cycle

Lignin is extracted from black liquor, explains Esther, but is still burned almost exclusively to generate electricity. In Germany alone, 50 million tons of black liquor are produced every year - an untapped potential, Esther believes. And then adds ironically that there's a saying in the industry: "You can do anything with lignin, except make money." With Jannis, she finally set to work to prove the opposite. But they weren't really interested in making money, she says, but in finding a substitute for environmentally harmful plastics, creating lignin-based products that - so the future tune - could rot in the forest or elsewhere. They did their research together with the WKI, which not only helped them with their chemical expertise, but also provided the machinery for the first prototypes and product trials. But what are we actually talking about here, what can be made with this oil-colored lignin?

Photo: Esther Kaya Stögerer, Jannis Kempkens

WKI chemist Lydia Heinrich first had to derivatize the powdery lignin in the laboratory in order to be able to process it further. This involves attaching other biobased molecules to the lignin structure, turning it into a solution and allowing it to take on different properties. The properties can result in a stable, but also flexible raw product. The respective chemically altered solution is the starting material for all other products created by BLACK LIQUOR's experiments. Esther and Jannis mixed it with different materials, such as the cellulose fibers or coffee grounds mentioned above. This has resulted in prototypes - a whole collection of materials - for furniture pieces and the fashion industry. As a flexible material, for example, a leather-like product can be created from which shoes or fashion items can be made. In the rigid version, Esther says, it can be used as a substitute for chipboard. Or as a coating for surfaces such as clothing, because lignin has water-repellent properties and, as a natural binder, can be combined well with a zipper. This is interesting for outdoor items, for example. Laser cutting can be used to give the materials - solid or flexible - any desired structure.

From the end of 2019 to the end of 2020, Jannis and Esther researched their idea with the help of their professors and the WKI of the Fraunhofer Institute. New lignin molecules were synthesized, designs were created, the material that emerged in the experiment was pressed, sawed, drilled, cut and sewn - and everything was meticulously tested for its practicality. The catch: none of it is fully developed. The stability of the material compositions created by BLACK LIQUOR do not yet stand up to the stability test to serve as, say, a substitute for chipboard. And the flexible version for leather-like products becomes brittle after a while. Some of the products have not yet been tested and await further trials. And all of the products currently take too long to degrade themselves so they can be returned to nature's natural cycle. After all, even a tree that rots in the forest doesn't decompose overnight; it takes years to decades. So turning lignin-based products into recyclable products still requires a good deal of research work.

BLACK LIQUOR is not yet mature as a market product. In order to turn lignin-based products into effectively recyclable products, a good deal of research work is still needed

But the potential is there, Esther says optimistically. In her master's degree, she wants to take the project into the second round and look for ways to improve her idea. How to create stronger, more flexible and more biodegradable lignin-based materials. "That's my approach," she says. So, together with her supporting professors from the Kunsthochschule Weißensee, her colleague Jannis and the Fraunhofer Institute for Wood Research, she is in the process of submitting a new application for research funds to the German Federal Ministry of Economics. She is also on the lookout for partners from industry and the startup scene who could jump on the bandwagon. Then there might soon be a lignin-based Ikea cabinet. It could then be called Svart Lut, black liquor in Swedish. One possibility among many.

The conversation is over. We say goodbye at the gate at the back entrance and each go our separate ways. The talk has whetted an appetite for the forest, which, it seems, is more than just symbolic of sustainability and a spirit of optimism. All good things come from the woods - as Gandalf once said.

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