Bolt Threads' New Hat Shows the Promise of Synthetic Spider Silk

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A hat made from Rambouillet wool is a perfectly nice hat. The fiber, shorn from a Rambouillet sheep, is fine and soft. Not at all scratchy. “They call it the American merino,” says Dan Widmaier, the founder of Bolt Threads, a biotech company that grows synthetic spider silk from yeast.

Earlier this year, Bolt bought Best Made Company, a high-design outdoor brand that makes hand painted axes and fancy toolboxes. It was an unexpected move—what did a biotech company want with a lifestyle brand, anyway? It turns out, Bolt wanted to make a new kind of wool hat.

For its first joint product, the companies are launching a limited edition version of Best Made Company’s Cap of Courage, a $198 striped beanie that’s made by combining Bolt’s Microsilk and Rambouillet wool. More than anything, the run of 100 caps is a proof of concept. It’s a way to show that the elusive science behind crafting synthetic spider’s silk is no longer elusive. In fact, it’s scalable enough that customers can walk into a store, pick up a spider silk hat, and wear it on their walk home.

Home-Brewed Silk

Five years ago that would’ve been unthinkable. Spider silk is an ace of a material. It’s soft, flexible, and strong as steel. But it’s also a terror to produce en mass. Spiders, no surprise, tend to cannibalize each other before they crank out enough silk to be useful. Scientists tried BioSteel goats, animals that are genetically modified to produce the filament of a Golden Orb spider, but that proved untenable, too.

Bolt Threads

For more than a decade, Widmaier has worked on solving the problem by growing proteins that mimic spider silk in yeast. “It’s been one of those things that’s often talked about as the next big thing but never actually getting out in the hands of consumers,” Widmaier says. And this year, he and his team of biologists got it right.

In the spring, Bolt released its first product, a $314 tie made entirely from synthetic spider silk. The cap is its second official good, and Widmaier says this is just the beginning of what Bolt hopes to do with grown materials. “We think the same process can make pretty much any protein based material nature has evolved,” he says.

In the case of spider silk, Bolt designed its fiber to mimic dragline silk, the flexible, kevlar-strong filament that a spider extrudes when it rappels. Analyze Bolt’s fiber and natural silk, Widmaier says, and you’d see the same molecular makeup. “All the things you observe scientifically are the same,” he says. “We just make it with a different process.”

Bolt Threads

Instead of harvesting silk directly from an arachnid, Bolt has figured out a way to brew it like beer. The scientists insert genes into yeast and then ferment the mixture with water and sugar. That solution is then purified into a silk protein powder and combined with a solvent so it takes on a molasses-like texture that can be squeezed through a die to make long, thin fibers. “It’s spider silk without the spider,” Widmaier says.

Bolt used the same process to make fibers for its tie and hat, but there are key differences. Bolt’s tie is made from a continuous filament yarn that’s woven into a garment. “It gives you a very clean, sleek face on the fabric,” says Jamie Bainbridge, VP of product develpment at Bolt. The hat, on the other hand, is made from spun yarn, which has an entirely different process. For the hat, Bolt’s spider silk is chopped into 4-inch-long pieces that are then entangled with the sheep’s wool and twisted to create a thick, airy yarn that’s meant to trap dead air and keep the head warm.

To the average consumer, the Cap of Courage will look and feel like a regular hat. Up close, you can see the dyed Rambouillet flecked with the white of Bolt’s silk, but there’s really no way to tell you’re wearing a wild new material. Bolt claims its fiber makes the hat softer, fluffier, and lighter than the all-wool original. Widmaier says it feels warmer, too, but as a scientist he’s hesitant to make any claims without empirical evidence.

Mostly, though, you’re paying for novelty. Bolt says eventually, after manufacturing scales up and the shiny newness of the material wears off, a hat and a tie will cost a whole lot less. For now though, $200 will get you a hat made of lab-grown spider silk and the rights to brag about it. No one said early adoption didn’t come at a price.