In Brest, on the coast of Brittany, Gwilen recovers marine sediment that accumulates in ports to transform it into objects and interior design components. A cross between terracotta and concrete, the material is obtained without firing.
As silt accumulates on harbor floors—a combination of clay, sand, shell waste, seaweed residue—ports need to be regularly dredged to maintain a sufficient draught. “And every year," says Yann Santerre, Co-founder of the start-up Gwilen, "because there is no recycling stream for the material, 40 million cubic meters of sediment is released into the sea, where it causes havoc with the ecosystem. Yet marine sediment has a lot of potential as it is largely composed of clay. And clay can be made into bricks!"
Bricks but also tiles, credenzas, tabletops, consoles or even lamps. With a look between terracotta and concrete—but with the density of terracotta—Gwilen’s material can be molded and tinted to obtain effects of marbling and gradations. Its Merrazzo, (a play on words: mer is sea in French) the alter ego of terrazzo, which contains oyster, mussel, and scallop shells.
The properties of the material—its mechanical strength and porosity—are akin to terracotta: "Depending on the application, it could be necessary to coat the material with linseed oil (as is done, for example, for traditional tommettes) or to wax it, like concrete, to make it water-resistant,” concludes Santerre.
The company’s first prototypes were show-stoppers at Milan’s Salone del Mobile in 2019. It had previously worked at the incubator of the Centre Scientifique et Technique du Bâtiment (CSTB'Lab) to standardize the material. Today it is working on new applications for flooring.
“The material can be worked just like ceramic except for the glazing part, a process that is contradictory to our approach,” given that it requires high-temperature firing and is therefore energy-intensive. "Our material generates four to five times fewer carbon emissions than the production of terracotta, which itself is already three times less emitting than concrete.”
So what is Gwilen’s manufacturing secret? "To solidify into the desired shape, we were inspired by diagenesis: the natural transformation of sediment into rock." In nature, this metamorphosis takes millions of years. But at Gwilen, the material sets like concrete in just 48 hours. No cement, no resin: nothing but the sediment itself.