Bolt Threads is a synthetic biology company that makes bio-engineered ingredients for the beauty and personal care industry. Its core product is b-silk, a biodegradable, film-forming protein ingredient produced by fermenting yeast with sugar and water. Bolt Threads positions b-silk as a sustainable replacement for silicone elastomers — widely used skincare, haircare, and color cosmetics ingredients that face growing regulatory pressure, particularly in Europe. Beauty formulators use b-silk as a functional ingredient that coats skin and hair with a lightweight film, delivering benefits like improved elasticity, softer feel, and anti-aging appearance. Bolt Threads sells b-silk by weight to prestige beauty brands and formulators — not finished consumer products — and has been selling commercially since 2019. The company outsources manufacturing entirely to a single third-party fermentation partner, Laurus Bio in India, using commodity inputs like urea, dextrose, and water. This asset-light model avoids capital expenditure but creates supply concentration risk; Bolt Threads is validating a second supplier. The long-term margin thesis depends on growing volume driving economies of scale, which reduces cost per kilogram, and eventually expanding into mass-market beauty and adjacent categories like household care and healthcare. Bolt Threads also has a newer variant, xl-silk, with enhanced solubility and skin/hair binding. The company holds 68 granted patents and 166 pending applications, with b-silk patents extending to 2042, which Bolt Threads views as central to maintaining pricing power as it scales.