b-silk
A bioengineered silk polypeptide for hair and skin, produced by fermentation and shipped as a functional ingredient in commercial products from Amika, Goddess, Vegamour, and Haus Labs.
b-silk was Bolt Threads' second silk product line, a bioengineered silk polypeptide designed as a functional ingredient for hair and skin. The protein was produced on the same yeast fermentation platform as Microsilk, then purified into a soft powder that disperses into formulations. It works alongside the structural proteins in skin (collagen, elastin) and as a film-former on hair: humectant, emollient, biocompatible, with claims of protection against pollution and blue light. Engineered to replace silicones, silicone elastomers, and keratin in conventional formulations, vegan and biodegradable.
b-silk launched in 2019 through Eighteen B, Bolt's direct-to-consumer beauty brand, with two debut products: a Revitalizing Hydrogel Moisturizer and a Hydrate + Restore Rich Cream. Since then, b-silk has shipped into commercial products from Vegamour, Haus Labs, Freaks of Nature, Amika, and Goddess Maintenance Co., across skin care, hair care, color cosmetics, and sun care.
The lesson was that a recombinant protein can be a real ingredient platform, not just a biomimetic story. Engineered with the right sequence, expressed at the right cost, and characterized against the right claims, it can compete head-to-head with conventional cosmetic ingredients on performance and price.