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Is Hemp a Sustainable Alternative to Virgin Cotton in Denim?

Industrial hemp is in the spotlight again, and for good reason. The new Farm Bill that the U.S. Senate passed 87-13 in December now legalizes the commercial production of hemp, freeing it from the grips of the Controlled Substance Act and severely curtailing the number of restrictions that have prevented farmers from raising it as a commodity crop like any other.

But it’s not all open skies for hemp. Individual states still have the final word regarding regulation, especially now that cannabidiol, the non-psychotropic component of cannabis better known as CBD, is rearing its head in everything from gummies to dog treats.

“Even if the government comes up with a regulatory framework, states have to adopt it,” said Mike Lewis, director of Thirds Wave Farms in Kentucky and one of the first private citizens to legally farm hemp—through a partnership with Patagonia in 2016—since its prohibition in the 1970s. “We have a long ways to go and a lot of legislating that needs to be drafted. But we’re heading in the right direction. I think it’ll be two or three years before it’s extremely common.”

There are plenty of reasons environmentalists go gaga for hemp. It uses about half as much water per season as cotton, requires no pesticides or herbicides and has uses that span an incredible gamut: paper, textiles, medicine, skin care and even construction materials and fuel. Taking to just about any soil, it grows fast—very fast. Hemp grows from seed to harvest in 90 to 100 days, compared with 150 to 180 days for cotton.

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Built for blending

As a textile, hemp plays well with other fibers, generously sharing its innate strength and durability. “Cotton is hemp’s best friend forever,” said Guy Carpenter, president of Bear Fiber, a North Carolina-based supply chain management firm that specializes in hemp. “Just an addition of 15 percent to 20 percent of hemp fiber into a yarn can make a fabric significantly stronger and more abrasion-resistant.” In denim, hemp absorbs indigo in a “more concentrated way,” he added.

More anecdotally, the fiber boasts increased wicking properties and superior temperature management, staying cool in summer and warm in winter. It may even have antimicrobial properties, though that has yet to be conclusively proven. “There’s a lot of claims but there’s not a lot of tests to back it up,” quipped Eric Henry, president of TS Designs, an eco-friendly T-shirt screen-printer from North Carolina that promotes local and transparent “seed to shirt” manufacturing. “There needs to be a lot more research done independently and not by the people that are ultimately selling the product.”

Industrial hemp and marijuana are both derivatives of Cannabis sativa, a slender weedy annual that was native to eastern Asia but now has a global distribution. “If you were to stand next to a hemp plant and a marijuana plant, it’s really hard to tell the difference,” said Roian Atwood, director of sustainability at VF Corp’s recently spun-off jeanswear division, Kontoor, which includes the Lee and Wrangler brands. “They look the same, they smell the same; they are inherently, from all appearances, the same plant.”

The essential—and regulatory—distinction between the two is their concentration of tetrahydrocannabinol, a.k.a. THC, the psychoactive compound that generates the buzz stoners crave. Per federal law, any breed of hemp with less than 3/10ths of 1 percent concentration of THC is classified as industrial hemp. “Fundamentally at the chemical level, industrial hemp is absent of THC,” Atwood said.

Farmers can cultivate varietals that are bred specifically for fiber, but more often than not, they will grow a so-called “dual purpose” strain that sprouts grain and flowerheads (used in the production of CBD) and supply fiber as a secondary function. “Even with the fiber varieties, the varieties of hemp that are most suited for our use, are not well bred,” Atwood said. “There’s not a lot of people pursuing that seed, knowing that the market is in CBD.”

Save for an isolated plot in Minnesota, virtually no dedicated fiber breed is being seeded right now, according to John Lupien, founder and president of Bastcore, a Nebraska-based decortication company that created a streamlined method of decortication to make quicker work of separating the bast-fiber bundles from woody hemp stalks.

Still, the dual-purpose varietals produce a “good quality fiber,” Lupien said. The key difference? They don’t produce as much fiber per acre—roughly between 18 percent and 22 percent of fiber per ton of harvested hemp versus upward of 25 percent to 30 percent for a dedicated fiber strain.

Hemp, blended in denim or otherwise, remains a niche product, in part because of the dearth of its availability in relation to cotton or even linen, which makes it far from cost-effective for brands on any kind of serious scale. (Again, this may change with the 2018 Farm Bill.) Compared with cotton, hemp requires extra steps for processing, which adds to its price tag. There’s the aforementioned decortication, which happens mechanically, then a wet-processing phase that uses an alkaline solution like sodium hydroxide to dissolve the lignin—a type of cell-wall “glue”—to release the bast fibers from their bundles. Finally, the fibers are carded and combed in preparation for spinning.

Cotton and hemp jeans by Prosperity Textile
Cotton and hemp jeans by Prosperity Textile Courtesy

Hemp, if processed injudiciously, can be pitted with irregularities: coarse in some areas, smooth in others. The more hemp a fabric incorporates, the greater the likelihood of irregularities, said Tony Tonnaer, founder of Amsterdam’s Kings of Indigo, which makes a small assortment of jeans that blend organic cotton with 25 percent to 45 percent hemp. (The hemp he buys costs roughly 20 percent more per meter than cotton, he noted.)

“If there are too many irregularities in the fiber of the hemp, it gives problems in the weaving or spinning machines,” said Tonnaer, who sources his fabric from Hemp Fortex in China, the world’s No. 1 supplier of hemp textiles, though France (“it’s just really expensive”) and Japan (“the hemp itself is from China”) present alternative options. Candiani in Italy also produces a denim blend of Belgian hemp and cotton.

Hemp can be finicky in other ways—like shrinkage, for instance. “Hemp shrinks more than organic cotton, so you have to be more careful with your patterns and the shrinkage percentage of your garments,” he said.

While hemp’s long-held (and perhaps undeserved) association with pot-smoking hippie radicals has not done it any favors, it’s its resemblance to sackcloth, both in look and feel, that gives most brands the greater pause.

“Hemp is traditionally uncomfortable,” said Paul Dillinger, head of global product innovation at Levi Strauss & Co. in San Francisco. “It’s rough with the visual characteristics of a coarse linen, which narrows its seasonal application. It’s not always a friendly fiber to wear.” That’s not to say you can’t teach an old yarn new tricks, however.

For their Spring/Summer 2019 collaboration, Levi’s Wellthread sustainability initiative and Outerknown, the eco-friendly men’s wear label founded by champion surfer Kelly Slater, are offering consumers for the first time a new “cottonized” hemp from Europe they claim is virtually indistinguishable from the white stuff. The process essentially transforms the corticated stalk of the hemp plant into a “puff” similar to a cotton boll and purging it of those dreaded irregularities.

Levi’s and Outerknown are offering an embroidered trucker jacket and a 511 slim-fit jean made from a 30 percent blend of cottonized hemp, but unless someone points it out to them, customers probably won’t be able to tell.

“We don’t need to advertise that it’s hemp as an excuse for the way the garment looks,” Dillinger said. “We can actually not say a word about it and expect this garment to perform as well as any 100 percent cotton garment. Whereas in the past it would have been a boardy, kind of crispy, rough denim, this is, I swear, softer than any cotton denim I’ve ever worked with.”

Environmental benefits

Hemp’s vaunted environmental profile doesn’t hurt, either. For a brand like Levi’s, which is trying to minimize its water use, cottonized hemp’s potential to fill in for a thirsty crop like cotton has tremendous appeal. According to a Levi’s life-cycle assessment, cultivating enough cotton for a typical pair of jeans guzzles 2,565 liters of water, more than any other stage in production. Blending a product with 30 percent slashes this by a third, “which is a pretty amazing savings,” Dillinger said.

And it’s not just water. Farmers can glean twice as much usable fiber per acre from a hemp field than a cotton one, he added. It’s a rotational crop that boosts soil health rather than depletes it. And because hemp isn’t dependent on synthetic chemistries, its cultivation has a carbon footprint “well north of 56 percent” lower than cotton, according to Dillinger.

“There’s a whole series of benefits that come out of that when you’re cultivating with less land and using less synthetic chemistry on that land,” Dillinger said. “You’re ending up with healthier communities, better groundwater stewardship and greater impact reduction.”

Bastcore is also working on creating a cleaner, more uniform fiber for spinners, but by using green chemistry to dissolve and reform hemp fiber—even the woody bits, which comprise 70 percent to 80 percent of the hemp stalk—in a closed-loop process that’s not unlike what Lenzing does with eucalyptus to make Tencel, except no pulping is required.

“We mill the material to a very fine powder and just dissolve it, and we can make the same type of fiber,” Lupien said. “We can bypass the chemical-intensive, environmentally problematic part of the rayon-viscose process.” But Bastcore has a more immediate—and more traditionally executed—objective as well: rolling out the first hemp denim fabric to be grown, milled, spun and woven entirely in the United States.

“We recently had our first commercial spinning trial Cap Yarns in North Carolina and it’s historic,” said Lupien, who anticipates an early summer debut. “It’s the first large-scale-produced hemp being spun on [an American] cotton system ever.”

He’s hoping to get the hemp blend rate to 30 percent or 40 percent, but even hitting 20 percent was no mean feat. “We don’t have a lot of access to spinning technology because the industry got decimated back in the ’90s, so there’s not a lot of survivors out there,” Lupien said. “And there’s not a lot of spinners that have the time or ability or desire to work with complicated fibers like this.”

Wrangler is also keen on building an American hemp denim product; it will just take time and no inconsiderable amount of effort. With this year’s Farm Bill serving as a catalyst for hemp to be more widely grown across the United States, all that remains is to shore up the infrastructure and foster a supply chain.

“If this supply chain and this growing community continues to expand and continues to look to build a vibrant cash crop around hemp, then we do need to be prepared to receive it and ultimately put it up into our product,” Atwood said. “The economics are still yet to be proven, but I think that in the event that everything proves itself out, why would we not source this versatile alternative fiber crop?”

For blue jeans, the most American of innovations, hemp, a crop cultivated by the Founding Fathers, adds a particularly poignant touch. It’s a sentiment that Atwood agrees with. “I think hemp and denim are a natural match,” he said.