To most people, spoiled milk does not present a lot of possibilities. But most people are not Gal Yakobovitch, 27, who can look at a dairy’s worth of spoiled milk and see a fashion opportunity.

That opportunity was a recent project Yakobovitch undertook with Shaggy Coos, a Connecticut dairy farm. Yakobovitch, who is from Israel and graduated from Parsons School of Design in 2018, said that casein, a protein in milk, which is more easily isolated when the milk has begun to curdle, was once used to make hard plastic. Those properties led her to the idea of making a natural water-resistant rubber from the protein, by purifying the milk and then melting the casein into a rubber-like substance. She then used it to turn upcycled cotton T-shirts into biodegradable, made-to-measure workwear for the dairy’s employees. Nothing is wasted; the natural components can return to nature; the workers have clothes directly suited to their needs. It’s a closed system—the holy grail of sustainable fashion.