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The Future of Sustainable Materials: Bison Wool

Whether in the form of super-soft bison "down" or ultra-insulating guard hairs, this meat industry byproduct deserves to be salvaged rather than sent to landfill.
Separating bison wool from a bison hide. Photo: Courtesy United by Blue

Separating bison wool from a bison hide. Photo: Courtesy United by Blue

As sustainability becomes an increasingly pressing priority in fashion and beauty, materials with a minimal ecological impact are being sought out by a range of brands looking to shrink their environmental footprints. In our series “The Future of Sustainable Materials,” we explore the innovations that could pave the way for a brighter tomorrow.

When fashion brands talk about diverting materials from landfill that could be made into clothing, they're often talking about using deadstock fabric or turning plastic bottles into recycled nylon. But United by Blue, an outdoor apparel brand, has focused its sights on something a bit less ubiquitous: bison wool.

Bison have thick, shaggy coats that contain fibers that are warmer than sheep's wool and can be as soft as cashmere, which were historically prized by the Indigenous communities that lived in close proximity to them. But contemporary ranchers raising the animals for meat often discard or throw away those coats. This is where United by Blue steps in, working with ranchers in an effort to salvage this valuable fiber and turn it into warm, high-performing garments.

"Basically, we take the hide, rescue the fiber from landfills or from being burned, and then return the hides to the meat processing plants so they can pass them on to tanneries," says Brendan Rauth, senior apparel designer at United by Blue, on the phone. "We did that primarily to keep the desirable fiber from being wasted."

Read on to learn more about what makes bison wool so special and what the challenges are for any brand looking to adopt it.

Bison on a ranch. Photo: Courtesy of United by Blue

Bison on a ranch. Photo: Courtesy of United by Blue

What is it?

Just like merino wool is grown by merino sheep, bison wool is grown by bison, also called American buffalo. Bison wool can be broken down into two main categories. Bison down, which makes up the animal's undercoat, is a soft fiber with a micron count of about 15, which means the individual fibers have a very small diameter and are incredibly soft. (For comparison's sake: cashmere has a micron count of 14, while extra fine merino wool has a micron count starting at 19. The lower the number, the softer the fiber.)

"It's pretty much the equivalent of cashmere," says Rauth of bison down. "It's really a luxury fiber. It has all the benefits you would get from super fine wool like cashmere."

These downy fibers make up roughly 15% of the bison's coat and can be used to knit items like socks, gloves or hats. Bison down is used for this purpose by a few other small brands besides United by Blue, like The Buffalo Wool Co

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The second part of the coat, called the guard hairs, make up the vast majority of the bison's coat, and as far as Rauth knows, United by Blue is the only brand using them in apparel.

"We're using the guard hairs, which are the coarser fibers, for insulation," Rauth says, pointing to coats like this one. "It has a lot of the same properties that you would get from merino wool: anti-microbial, there's no known allergy to it, it's warm when wet. It's a hollow fiber, so it has great insulatory properties."

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How is it produced?

Unlike sheep or goats, which can be shorn regularly throughout their lives, "bison are not super interested in holding still to be sheared," Rauth says. As a result, the fiber can only be gathered as a step prior to tanning the hides for leather. While learning that the fiber can't be harvested from still-living animals may not be great news from a vegetarian perspective, zero waste advocates would likely argue that it still makes more sense to rescue fiber that was being created anyway and is otherwise destined for landfill.

Preparing the fibers for use in apparel involves six or seven different steps, says Rauth.

Sorting bison fiber. Photo: Courtesy of United by Blue

Sorting bison fiber. Photo: Courtesy of United by Blue

"There are the original bison ranchers who we contract with, the meat industry packing plants that we lease the hides from, the scouring facility, which is where they wash the hides and the dehairing facility, which is where they separate [the fiber from the hides]," he explains. "Then the fiber gets split into two different batches: one for the production of yarn textile like hats and beanies and the other which goes to an insulation manufacturer."

What are the challenges involved in using bison wool?

This extensive process, with very little established infrastructure in place to support it, is part of why bison wool isn't already more common in apparel.

"The management of the supply chain is very expensive and labor intensive," Rauth says. "We have a couple of people here on staff who most of their job is just managing the bison supply chain... There is no just fiber supplier set up for bison currently. Most people don't do it just because it's a total pain."

The other difficulty is the inconsistency of yield. Because bison fiber is collected at the end of the animal's life, rather than regularly throughout it, it's much harder to estimate how much fiber will be available, which makes it harder to plan how much product you can make with it.

"It's very difficult to predict," says Rauth.

Bison fiber ready to be used in apparel. Photo: Courtesy of United by Blue

Bison fiber ready to be used in apparel. Photo: Courtesy of United by Blue

What's next for bison wool?

Though bison wool is most often used for the down, United by Blue's incorporation of the guard hairs into insulation has proven that the fiber is more versatile than that. Rauth says the brand has even talked about selling the fiber directly to other companies now that it's gone to the work of setting up the supply chain, though he's not sure whether that will end up happening or not.

Either way, he hopes that other brands will learn from United by Blue's experience with the fiber. There will never be one "silver bullet fiber," whether it's organic cotton or recycled polyester, that will solve all of fashion's sustainability woes, he says. Instead, true sustainability is about looking to balance a currently unbalanced system.

"We need a diverse base of fibers that we're producing textiles from in order to not stress any part of the system too far," he says. "Bison is a good example of finding new and innovative fibers that aren't currently causing stress on the system that are just not being utilized."

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