Coffee-based yarn knits a better sneaker for everyone

Published 08 July 2019

Posted by Stephen Holmes

Article tagged with: design, materials, materials developments, sportswear, coffee, materials information management, sneakers, finland

Recycled coffee beans are being used to create a new fabric yarn with some interesting properties you perhaps wouldn’t expect while downing your fifth Monday morning espresso.

The basis of footwear start-up Rens’ latest sneakers, the upper is knitted from a blend of coffee yarn and recycled polyester, before a waterproof nano membrane is laminated between the shoe upper and inner lining.

Aside from the waterproof properties of the membrane layer, the coffee yarn brings some other bonuses - its antibacterial, has micro-pockets in its structure that help trap and release bad odours and dry twice as fast as standard polyester, and it is resistant to fading by UV light.


It’s the eco-friendly brainchild of co-founders Son and Jesse that are huge sneaker-heads and wanted to design a shoe with sustainability at its core.

The designs were developed with an industrial designer in Germany, while the rest of the team are based at Rens’ headquarters in Finland.

“We wanted to create a smooth and seamless sneaker that would feel both nice and comfortable to wear,” says Jesse, ” However, the final design we have now has been fixed and further developed with our partner material suppliers and manufacturers in order for it to have the best technical aspects inside the shoe.”

The use of the coffee grinds is a move that could have a big impact - 23 million tons of organic waste is produced by the coffee industry every year, and simply leaving it to decompose produces vast amounts of harmful methane gas.

300 grams of used coffee grinds go into the manufacture of each pair of shoes, along with an abundance of recycled plastics, but it was still a step into the unknown using the yarn.

“Since we’re really the first in the world to implement coffee yarn on active sneakers, it took us much more time to adjust every detail of the shoe as well as a lot more effort to adjust and develop the material to fit seamlessly with the design,” says Jesse.

The team worked through ‘over 100 iterations’ of the design, eventually arriving at the fully waterproofed low-top, wraparound design that has launched successfully on Kickstarter - find out more here.

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