The Plastic Shell Chair Gets Remade With Hemp + Seaweed

03.29.24 | By
The Plastic Shell Chair Gets Remade With Hemp + Seaweed

The plastic shell chair is an iconic design, one we’ve seen many iterations of throughout the years, but never like this where the material is the main priority. Designed by Foersom & Hiort-Lorenzen and produced by Normann Copenhagen, the Mat Chair is the product of years of research, prototyping, and testing (about 20 years in total) to find a better alternative to plastic when designing furniture – hence the name, Mat, for material innovation. With circularity at the forefront of the design process, the new contemporary shell chair challenges material and production norms while inspiring sustainable post-production methods.

chair prototypes and sketches

The Mat Chair feels familiar with its timeless silhouette and ergonomic curves. The shell is also what is most unique about, and is the essence of, the chair. It’s crafted using hemp fibers sourced from nearby regions that grow the crop for the food and pharma industries that use its leaves and seeds. The Mat Chair, instead, uses the stems.

chair prototypes and sketches

hand holding chair prototype on a table of sketches

chair in front of a large pile of hemp fibers

The idea to use hemp comes from the fact that it’s an incredibly beneficial and sustainable crop. It sequesters about 15 tons of CO2 per one hectare of hemp and is environmentally friendly, requiring minimal water and zero pesticides or fertilizers. Hemp grows quickly, allowing it to be harvested frequently.

chair in front of a large pile of hemp fibers

chair in front of a large pile of hemp fibers

chair in front of hemp plants

chair in a field of hemp plants

chair on the beach next to seaweed

The Mat Chair also comes in a version made of a mix of hemp and eelgrass, a type of seaweed. While less common by industry norms, Denmark, and specifically the island of Læsø, has a history of using the resilient algae in roofing. Seaweed is also a big sequester of greenhouse gas emissions and has little environmental impact. Rather than being harvested from the ocean and damaging underwater ecosystems, the eelgrass used in the Mat Chairs is collected from the coastline of Denmark where the material would naturally wash ashore.

two chairs on the beach next to seaweed

hands holding material sheets

The hemp fibers and dried eelgrass are first sorted and milled, then mixed with a special, fully recyclable binder. The mix turns into sheets of the new, innovative material which is then pressed into chair shells.

shell chair being pressed into shape

man pressing mold of shel chairs

stacks of chair shells

hand holding a chair shell with two finishes

shell chairs lined up against a wall

man oiling a chair shell in production facility

After, the shells are cut to size, hand-sanded, and hand-oiled with a VOC-free linseed oil for a final finish. Offcuts from the cutting process are also recycled and put back into the milling stage, ensuring a completely zero-waste production. The shells are then mounted onto a powder-coated steel base in either Black or Cream.

chair in front of a production table in a facility

chair in front sheets of material

Once the Mat Chair reaches its end-of-life, the base can be disassembled and the shell is recycled back into the production line. The entire process – from the years of research and testing to finally creating the chair and the production method – highlights the possibilities that can be realized when we prioritize the planet and strive for a better, greener future of design.

five shell chairs

The Mat Chair collection consists of a dining chair, a dining armchair, a barstool in two heights, a bar chair in two heights, and a bar armchair in two heights. They are all available in hemp or a hemp and eelgrass material, and with front or full upholstery.

black upholstered shell chair next to side table

shell chairs around a round table next to windows

three shell chairs next to a window with curtains

shell chairs in a restaurant environment

barstool shell chairs next to a shelf with books

shell chairs in a conference room environment

To learn more about the Mat Chair collection, visit

As the Senior Contributing Editor, Vy Yang is obsessed with discovering ways to live well + with intention through design. She's probably sharing what she finds over on Instagram stories. You can also find her at