Designing with Chitosan

San Francisco

21 October 2020

“Choose the blue fish.”

You've likely seen the label of the Marine Stewardship Council (MSC) – a blue oval inside of which a white tick forms the backbone of a fish. The MSC is an international non-profit working to certify sustainable fisheries, with its label appearing on fish products that meet its standards. “Choose the blue fish,” the organisation implores, stating that it uses its “ecolabel and fishery certification program to contribute to the health of the world’s oceans by recognising and rewarding sustainable fishing practices”. Now, for the first time, it is working with apparel.

This week has seen the San Francisco-based footwear brand Allbirds launch its first line of apparel. The collection of T-shirts, jumpers, cardigans and puffer jackets are made from the brand's existing material palette of certified merino wool and eucalyptus tree fibres, but it is the addition of a new fibre within the T-shirt blend that is most noteworthy. XO is a chitosan fibre – a natural biopolymer extracted from crustacean shells that Allbirds has sourced from MSC-certified fisheries. The fibre has anti-odour properties, derived from its presence in crustacea to help inhibit bacteria. For the T-shirt, Allbirds has woven chitosan into its existing Trino yarn – a blend of eucalyptus tree fibres and merino wool – creating Trino XO.

The use of Trino XO is intended to reduce the need for washing, thereby helping to lower the T-shirt's overall carbon footprint. To understand more about the development of the chitosan fibre, its use in the range, and Allbirds involvement with the MSC, Disegno spoke to Jad Finck, the brand's vice president of innovation and sustainability. An edited version of this interview follows below.

Disegno How different is Trino XO to the existing Trino yarn? How big a change does the introduction of chitin represent?

Jad Finck It is a big change because it provides the functionality of a natural anti-odour platform. That took a lot of work, not only to get a pure fibre that could work in apparel, but to make it work within our particular Trino blend. The fibre is made of chitosan, which will be appearing in its pure form in a mainstream apparel item for the first time. Its use originated in the medical industry, and while there have been some previous attempts to use it as a coating, or diluting it and trying to put it into other fibres, it didn’t keep its efficacy over time. We’ve been able to deliver a pure fibre that you can wash and which maintains its ability to inhibit odour-causing bacteria. It’s a minority component, but has a pretty big effect. That we’re able to bring in anti-odour technology through the use of a natural material is really exciting.

Disegno What has chitosan been used for in the medical industry?

Jad They use it in healing, so it’s included in certain bandages because of its bacteria-inhibiting nature. That’s an evolutionary trait of chitosan from where it appears in crustacean shells to naturally inhibit bacteria.

Disegno The inhibition of bacteria is how it’s anti-odour?

Jad Exactly. We wanted to deliver a T-shirt you don’t need to wash as much because you know there’s an odour-fighting technology keeping it fresh. Not only is that convenient, but we’ve seen that the use phase of a garment – washing and drying it over the lifespan of a product – can really swing its carbon footprint one way or another. By providing something you don’t need to wash as often, you're actually lowering the carbon footprint of the life of the product.

Disegno How is the XO fibre produced?

Jad It starts from discarded crab shells and, importantly, it’s a byproduct of the seafood industry. We’re working with the Marine Stewardship Council (MSC), which is a seafood certification – they’ve never worked with apparel before, but it’s the gold standard of sustainable fisheries. It’s been a head-scratcher, but the MSC are excited to expand the certification and not just tell seafood folks about their crab meat, but to tell T-shirt folks about a product derived from waste. Number one, it’s waste; number two, it’s natural; number three, it’s from a sustainable fishery.

Disegno What was that process of making links between industries like?

Jad It wasn’t difficult, but it was kind of quirky. There was surprise and wonder initially, but they’re obviously excited about novel reuses of byproducts coming down their supply chain. The certification industry has been really collaborative, but the links don’t happen overnight – it’s a bit of a white space, but we’re making good progress with it. Now that there’s a supply chain and certification, we’re trying to figure out the answers to make it a little bit more repeatable for us and hopefully other people as well.

Disegno Have you had conversations about the fact it’s a byproduct of fishing? Many people may buy the brand, for instance, because they don’t want to wear leather shoes. Does the inclusion of a crustacean product present issues?

Jad We’ve definitely discussed that. We’re looking at how we can provide something that adds value, lowers the overall carbon footprint, and makes it more user-friendly and comfortable. But you need to look at all the effects. So the primary effect we’re trying to avoid is any of the concerns with silver and zinc, because anti-odour platforms are normally metal-based. No matter where you read about those materials, it’s undeniable that there is concern about their extraction and concerns about ions leaching into the environment. We wanted to avoid all of that and instead focus on finding an entirely natural alternative. Chitin is a natural biopolymer and the second most abundant natural biopolymer on earth after cellulose, which is also in the product. So we’ve got abundant natural biopolymers in there, but we do also talk about the fact that there are folks with vegan considerations, just as we talk about the fact that there are folks with non-natural material considerations. But I think that as an overall target, we’re looking at being able to harness nature and provide something that doesn’t rely on dirty or extractive non-renewable materials. Then we feel it’s important to say exactly what is in a product so you can make your own choices about it.

Disegno How widely used is chitin?

Jad There are niche uses for it in healthcare and some maternity products, but it’s not been successfully used in mainstream products. The challenge was how to get it into a product that is reusable and which gets washed, because the medical applications are typically one-use. In that context, you don’t have to worry whether it stays in the product for a long time, so you can use powders, treatments, or coatings. They’re worried about one-time efficacy, whereas we wanted to focus on the pure fibre so we can have it for the full life of the product.

Disegno How do you go from the shell to the fibre. What’s the process?

Jad It’s called deacetylation, which is basically a fancy way of saying you’re dissolving the crab shells to get a liquid polymer suspension. Then you extrude that into fibres. Our tree material is similar – taking the cellulose from eucalyptus, getting it down into a liquid or gel state, and then extruding it. You want to get it into a fibre that can be used in the machines that spin yarns and knit garments.

Disegno What’s the challenge of that? You mentioned that people have looked into it before, but not particularly pushed ahead with it. Is there a challenge in getting it into that fibre state?

Jad The status quo and inertia was part of it – people were only using it for a short time, rather than long lasting applications. The other part of the challenge is that it’s relatively fragile in the development process. When you’re dyeing clothes or heat-setting clothes, there are different processes that could deactivate the function if you’re not careful. That’s where we had to do a lot of trial and error. You can get it into clothes, but you want to make sure you protect that natural odour-fighting quality.

Disegno How does it compare functionally to Trino?

Jad The beautiful thing about it is that once you get it to work, it’s a really soft fibre. You don’t need to put much in and, if anything, it helps the hand feel. So it’s a very small percentage, in the order of 5 per cent, but then it’s a case of making sure we can dye it the way we want it to, heather it the way we want it to. It can now hold up in normal production without being fragile as it was when we first started with it.