Called Why Knot, the sheet material is made of Japanese knotweed, an invasive plant in the Netherlands.

Japanese knotweed (Fallopia japonica) is a fast-growing plant and considered to be one of the most invasive exotic species in the Netherlands. Once the plant is established, it is very hard to get rid of. It displaces native plant species, and its invasive root system and strong stems can cause damage to buildings, pipes and roads. Combating the knotweed costs millions a year, and the removed plants are generally burned.

Each year, the Dutch innovation hub BlueCity holds several Circular Challenges, challenging young designers to do something useful with things normally considered waste in collaboration with companies and organisations who provide the waste. Each team gets six weeks to come up with a solution. Regional water authority Schieland en de Krimpenwaard each year removes over 1000 m2 of Japanese knotweed, and each year, this amount increases. They provided this material to team Why Knot.

The team developed a sheet material made of Japanese knotweed. The material is strong and light, thanks to the layered fibres of the plant. The weed is cut into pieces and heat pressed into a sheet material. This makes the material more sustainable than other sheet material, which often contains glue with formaldehyde.

Why Knot won the first Circular Challenge of 2022. Find this material in our library here.

Photo: BlueCity / Why Knot