Case Study

Stella McCartney’s Wool Yarn

From sheep to Gold level certified wool yarn, Stella McCartney's journey down the road less taken and its hard-won results. 

It’s not surprising that high-design ideals suffuse everything Stella McCartney does: it’s a luxury brand with well-known and industry-respected ethical bona fides. So when the company decided to pursue Cradle to Cradle Certification, only Gold level would do.

As the company was very familiar with all the options for sustainability labelling and certifications in the fashion world, the team knew it was looking for something different. Stella McCartney’s team wanted a robust assessment for its own material (though they weren’t sure which one yet), which they found in Cradle to Cradle. Beyond a high standard, Stella McCartney wanted a progressive goal that would push its brand—and potentially the fashion industry as a whole—forward. “We were really looking for a program driving change to healthier materials,” said Claire Bergkamp, Stella McCartney’s head of sustainability and ethical trade. She appreciated that there was a real focus on creating building blocks for the circular economy. She saw Cradle to Cradle certification as a tool for “moving that process forward.”

The Fashion Positive team assisted Stella McCartney from the get-go, in a relationship that both call “highly collaborative.” Questions were answered and consideration given to how Fashion Positive could facilitate the specific goals of the luxury fashion brand via the Cradle to Cradle Certification framework.

Though the brand knew it wanted to work toward certification of a material, the decision had to be made about what exactly would be the most impactful. Stella McCartney’s team chose wool because, “out of the materials we use, when we were looking at certification, it made sense to pick a building-block material. A wool yarn can go into many products—both knitwear and other things,” Bergkamp said. Stella McCartney could use it in multiple collections, over many years, for both men’s and women’s fashions and accessories.

Wool is a notoriously strong, flexible, biological material. To coordinate on the Gold level standard required working directly with the mill and the various suppliers of dyes and detergents used on the material. 

For that job, Cradle to Cradle certification requires an independent assessor. Working in that capacity on this project was Ignasi Cubiñà, the cofounder and director of Barcelona-based Eco-Intelligent Growth (EIG). Cubiñà and his team made sure that Stella McCartney’s standards for quality were met, and they also ensured that the Cradle to Cradle criteria in all five categories were up to the Gold level standards as defined by Fashion Positive: material health, renewable energy and carbon management, clean water, social fairness and material reuse.

The No. 1 goal is to push for change in the industry.

Claire Bergkamp, Stella McCartney’s head of sustainability and ethical trade

With every certification comes unique challenges. One was getting pesticide-free wool, since ensuring that a biological material can be returned safely to the environment is a requirement of the Gold level standard. For example, disallowed chemical residues from pesticides used on the sheep counts against the material health of the yarn. That meant Cubiñà’s team had to work directly with the sheep farmers and get the various farms on the same page about what they could and couldn’t use when protecting their flock against the insects that can infest sheep. Cubiñà says having a strong brand like Stella McCartney behind the decision was helpful for making that change happen. During the process it was of the utmost importance to Stella McCartney to ensure that the approved chemicals were also able to best support the animal welfare of the sheep. Stella McCartney prides itself on working with the farms that practice the highest levels of animal welfare, and because of their commitment on this topic, animal welfare was kept at the forefront of all the conversations and decisions around getting pesticide-free wool.  

By far the biggest challenge with certifying the yarn came after the wool got to the mill in Italy. The chemicals used in the product and product components had ingredients that didn’t fit the Cradle to Cradle Certification standards for material health.

Cubiñà worked with the mill on a consistent basis, and he says the fact that he’s an independent assessor makes all the difference: “They have a strong incentive to share confidential information with me, since I’m in-between the brand and the certifier. That is why Cradle to Cradle is such a powerful tool; that level of trust,” he said. While the standards are stringent, the suppliers ultimately respect that the certification isn’t just good storytelling or PR but rather the real deal in pushing for beneficial change. As a result, they tend to be more collaborative and dedicated to making all parties satisfied, including Stella McCartney and Fashion Positive.

99.5 percent of Stella's wool yarn is made of Cradle to Cradle Certified™ ingredients.

Ignasi Cubiñà, Cofounder and Director of Eco-Intelligent Growth

“Having someone that knew that cultural context and knew the players and how to drive change, was key,” said Bergkamp of working with Cubiñà’s team.

Working directly with the wool producers and the mill, Cubiñà promoted “dramatic” change over time in the material health of the wool yarn. “From the start of the raw material, in avoiding use of pesticides, and selection of those farmers who guaranteed not to use them, to the detergents, the leveling agent, the biocides and the processing chemicals—all of these were changed. More than 70 percent of the chemistry has been improved. The dyes are all new—none of them were allowed before,” said Cubiñà.

Did this all take time—more time than they had bargained for? Like any kind of design, that which is well done means answering questions fairly and getting to the root of things—and there was a lot of digging when it came to chemicals in this foundational wool yarn for Stella McCartney’s product line. “We went much deeper into the supply chain than I had imagined at first,” said Cubiñà. So yes, that took more time than expected. That’s OK, says Bergkamp. “The No. 1 goal is to push for change in the industry.”

Cradle to Cradle Certification

The Cradle to Cradle Certification process guides designers and manufacturers through a continual improvement process that looks at a product through five quality categories—material health, material reutilization, renewable energy and carbon management, water stewardship and social fairness. A product receives an achievement level in each category—Basic, Bronze, Silver, Gold, or Platinum—with the lowest achievement level representing the product’s overall mark. 

Optimization Results for Stella McCartney's Wool Yarn

Material Health
Challenge: Many prohibited chemicals; none of the dyes were allowable under the standard.
Optimization: Chemistry of yarn was changed by over 70 percent; all new dyes were used.
Material Reutilization
Challenge: Wool is naturally biodegradable, but dyes and finishing chemicals contaminate the fiber. A nutrient management strategy had to be defined by the yarn manufacturer for chemical optimization of the product for human health and environmental safety.
Optimization: When clothes eventually make their way to the earth, they contain no materials that will pollute.
Water Stewardship
Challenge: Water effluent rules in the area of Italy where the mill is located are high already, but it wasn’t good enough for Gold level certification.
Optimization: The chemistry was improved, and the wastewater treatment in place degrades molecules potentially hazardous to environment.
Renewable Energy
Challenge: The mill previously operated on 50 percent renewable power. Offsets needed to be purchased for the other half.
Optimization: Stella McCartney used carbon offsets for the nonrenewable energy used at the mill (allowed under the certification standard); mill plans on installing more renewable energy on-site in the near future.
Social Fairness
Challenge: No issues needed changing. The mill is an old company with strong community ties and Stella McCartney is a member of the Ethical Trading Initiative.
Optimization: All chemicals used were able to best support the animal welfare of the sheep.