Unraveling The Secrets Of Closed-Loop SeaCell Clothing

Bamboo viscose is not sustainable. SeaCell is. Here's the difference.

“Closed-loop” has become something of a buzzword in sustainable fashion circles, but what does it really mean?

Over the years, as a sustainable fashion editor, I’ve researched and personally tested my fair share of “sustainable” fabrics, from bamboo viscose rayon that turned out to be less eco-friendly than promised to SeaCell that genuinely lived up to the hype.

Oliver Charles is known for their buttery-soft sweaters made of yak wool. I have personally tested and loved my yak wool sweater for years. 

When they released a new SeaCell T-shirt made in a fully closed-loop process, I was curious to see if the promise of circular fashion translated into real-world wearability.

What Does “Closed-Loop” Mean In Clothing?

At its core, a closed-loop system is a way of making yarn where resources are reused and recycled instead of being flushed into waterways.

On the other hand, in an open-loop system, toxic chemicals are used and discarded, polluting rivers and endangering workers.

Traditional bamboo viscose rayon is the most common version of open-loop fabric that you'll find. It's in a lot of athletic clothes and often framed as sustainable. However, viscose is made through a cocktail of caustic chemicals, including sodium hydroxide, sulfuric acid, and carbon disulfide (CS₂).

In large amounts to dissolve cellulose so it can be reformed into fibers that are not recycled between uses. Instead, they get washed down the drain… and into the environment.

Circular Fabric Spotlight: What Is SeaCell Fabric?

Now, how does SeaCell fashionably fit into the conversation? What is it exactly?

It’s made by reconstructing cellulose (plant cells) and then spinning it into fibers that can be blended with other materials like cotton and wool or spun on its own into yarn.

It’s made in a closed-loop, which does not release solvents into the environment, unlike viscose. An organic solvent is used throughout the entire closed-loop process, and the Forest Stewardship Council has recognized the solvent as non-toxic. SeaCell combines two different plant fibers, seaweed (obviously) and wood pulp harvested from eucalyptus tree farms.

Seaweed is regeneratively farmed from the cool blue fjords of Iceland every 4 years. Similar to how yaks graze, we only take the tops of the plant, leaving the lower sections to regenerate.

The wood pulp comes from Eucalyptus and Beech Trees, two fast-growing trees that require little water.

These trees are harvested in Europe from Forest Stewardship Council (FSC) certified tree farms. The FSC certification means that a newly planted tree must replace every tree used in the production of SeaCell.

Seaweed grows quickly without pesticides or farmland, in contrast to eucalyptus and beech trees that grow more slowly. And while SeaCell does still utilize some wood pulp, the addition of seaweed cuts this down significantly, reducing strain on much more slowly replenishable resources in favor of a constantly renewable one.

All this results in a fabric that, in my experience, wears like a second skin. It's light, breathable, and soft enough to keep you comfortable on its own or layered under a sweater.

During my wear test of my new SeaCell T-shirt, it felt weightless but far from flimsy.

I also appreciate that the SeaCell is not only healthy for the body due to lack of toxic processing, but also kind to sensitive skin like mine. The fiber is hypoallergenic, and the seaweed content is believed to retain antioxidants that may soothe and protect. While I couldn’t measure that claim firsthand, I can say the fabric remained gentle and irritation-free throughout long hours of wear.

Why Closed-Loop Fabric Systems Matter

The difference between closed-loop and open-loop production isn’t just a technicality; it’s the dividing line between textiles that protect ecosystems and people, and those that actively harm them.

The chemicals flushed away after a single use in an open-loop system find their way into rivers and groundwater, poisoning aquatic ecosystems and leaching into farmland. Communities downstream bear the brunt, with water supplies contaminated by toxic residues that can take years to break down.

Viscose production, for instance, has been linked to severe pollution in regions of China, India, and Indonesia, where entire waterways have turned lifeless from unchecked industrial discharge.

At the Aditya Birla viscose factory in India, investigations revealed water near discharge pipes was “extremely polluted,” failing local water quality standards, with downstream communities suffering health effects and environmental degradation.

Besides water pollution, air pollution is also a major consequence. Carbon disulfide can volatilize, contributing to atmospheric emissions that affect both ecosystem health and air quality nearby.

The social impact is just as critical, especially considering many factories have inadequate or nonexistent protective equipment.

Carbon disulfide in particular is known to cause neurological damage, reproductive and hormone issues, and in severe cases, death. One study of rayon workers in Taiwan exposed to carbon disulfide found that among exposed workers, 43.4% had hypertension compared to 7.1% in the controls.

This is where closed-loop systems make a major difference. No toxic chemicals. No wasted resources. And because the resulting fibers are still compostable at the end of their life alongside purely natural materials like yak wool, they offer a rare example of true circularity in fashion.

SeaCell is a material that gives back to the earth rather than lingering as microplastics.

Oliver Charles And The Future Of Zero-Waste Clothing

Closed-loop fabrics aren’t just a niche innovation; they’re a blueprint for where the fashion industry could (and should) be headed.

As demand for transparency grows, brands that embrace circularity will be better positioned to lead the charge toward a fashion economy where waste is designed out of the system.

Oliver Charles has already carved out a reputation for elevating wardrobe staples through thoughtful material choices. By introducing a new SeaCell line into their lineup, they’re expanding that philosophy beyond sweaters and into year-round basics.

Their approach shows that sustainability doesn’t have to be a side category. It can be woven into everyday essentials. With their commitment to closed-loop cellulosics and pure, natural fibers, Oliver Charles is helping prove that circular fashion, both in terms of fiber production and end-of-life disposal, isn’t a trend, but a future standard.

If you believe that every good wardrobe starts with owning less and owning better, consider buying yourself an OLIVER CHARLES sweater.