From waste to walls: how 'seawool' offers new uses for mussel beards

A start-up company creating a biodegradable ‘wool’ material from by-products of the Scottish shellfish sector has relocated its headquarters to Glasgow in a move that will underpin future growth and shorten its supply chains.

Seastex uses mussel beards or byssus – the threads that help mussels attach to surfaces in the ocean such as ropes, rocks or each other – to create a natural textile that can be used for acoustic insulation, upholstery, and a range of other purposes.

From its new base in the east of Glasgow, Seastex hopes to increase production and expand the team from two to 40 people over the next five years. The business is collaborating with Scottish shellfish cooperatives to secure approximately three tonnes of the raw material per week. The Scottish Shellfish Marketing Group’s mussel processing facility at Bellshill is just seven miles away.

Seastex has successfully designed and built a prototype production line and is striving to scale up production further by 2026, with Scotland’s Industrial Biotechnology Innovation Centre (IBioIC) set to support future stages.

A record-breaking 10,000 tonnes of mussels were produced in Scotland in 2023, with estimates suggesting up to a third would have been discarded as waste, often ending up in landfill. Waste products typically include mussels deemed unsuitable for sale due to shape and size, cracked shells, contamination by wastewater, algae, sediment and the inedible byssus threads.

After cleaning, the mussel beards are dried to create a material Seastex internally refers to ‘seawool’ which is free from chemicals, and is recyclable, lightweight and naturally fire retardant. Its first product for the construction sector, an acoustic panel for soundproofing, was launched at the London Design Fair in 2023.

The company’s chief executive and founder, Sander Nevejans, said: “The idea for Seastex came to me after watching a documentary on mussel farming, where I noticed de-byssing machines cutting off the beards during the cleaning process before the mussels were bagged and sent to stores. Until that point, byssus had never been used as a textile material. However, a similar material, ancient sea silk - made from the byssus of the noble pen shell (Pinna nobilis), a type of clam - was once woven into garments for nobility and religious leaders around the Mediterranean over 2,000 years ago.

Sea silk reimagined

“As the sea silk industry overseas has all but disappeared - due to overfishing, the decline of seagrass beds, and a bacterial outbreak causing a mass die-off of the now endangered noble pen shell - the ambition is to collaborate with shellfish producers to reimagine this material for the 21st century, reviving and preserving a part of this ancient craft. Moving to Glasgow is a critical step in our growth plan and brings us closer to the essential supply chain that can ensure access to even more mussel beards to turn into new products.

“The plan is to significantly expand the range of applications for our seawool over the next decade, but at the moment we are particularly interested in acoustic applications for buildings. Using a bio-based material could help to transform the carbon footprint of insulation compared to the likes of glass wool, rock wool, and petroleum-based products, which can also be tricky to work with. Once an interior needs refurbishment, our products can be easily renewed and the material recycled, as no synthetic glues or bonding agents are used in seawool – it can be reused time and time again.”

Helping reach net zero

Dr Liz Fletcher, director of business engagement at IBioIC, said: “Increased development and adoption of bio-based materials will be a key part of Scotland and the UK achieving net zero, and Seastex is a great example of a startup making significant progress in that area.

“The feedstock used by the business is typically considered waste, but for the construction and textiles sector it could be incredibly valuable for its green credentials. We look forward to supporting Seastex to scale up and see the material used in even more settings.”