Microsilk
Bolt Threads' first product line. Recombinant spider silk produced by fermenting engineered yeast, spun into fiber, and knit into garments. Shipped with Stella McCartney and adidas. A Microsilk gold dress was exhibited at the Museum of Modern Art.
Microsilk was Bolt Threads' first product line. We studied the genetics of spider silk to understand how arachnids spin fibers with extraordinary tensile strength, elasticity, and softness. Then we copied the relevant DNA into yeast, fermented the engineered cells at industrial scale, purified the resulting silk protein, and extruded it into fiber that could be knit into garments. The end product was a fully biodegradable spider silk yarn that had never existed outside of a spider.
Microsilk shipped across multiple categories. Stella McCartney designed a gold Microsilk dress for the Museum of Modern Art's 'Items: Is Fashion Modern?' exhibition in 2017. That same year, Bolt sold its first commercial Microsilk product, a 50-unit limited run of $314 neckties, and Best Made Co. (later acquired by Bolt) released a 100-unit run of Microsilk-blend beanies. In 2019, adidas by Stella McCartney debuted a fully biodegradable Microsilk tennis dress worn by professional players.
Translating that molecule into a real product required solving every step in turn: titer, downstream, mechanical properties, hand-feel, cost, and a yield curve that could feed real production. Microsilk was the proof that engineered protein fibers could leave the lab and become something a person could put on.