First came pleather made from plastic. Then there was plant-based leather—made from fruit like pineapples—and fungi-based leather made from mycelium, the network of vegetative threads that grows in mushroom colonies. Startups like Modern Meadow biofabricate leather in a lab. Now comes another alternative: Making leather from silk.

“Basically, it’s like cooking pasta,” says Fiorenzo Omenetto, a professor at Tufts School of Engineering and director of the Tufts Silklab, where researchers developed the material. “You take the [silk] fibers and boil them in water with salt that cleans them, and then there’s a second salt that breaks them down.” When the salt is extracted, you’re left with fibroin, the protein that makes up silk. At the lab, the researchers have transformed silk into everything from gels to electronics.

In this case, they combined the silk protein with some other natural materials, including cellulose from agricultural waste and chitosan, a material found in shellfish waste. The mix was 3D printed in patterns designed to mimic the look, feel, and texture of leather.

Typical leather comes with a large footprint; a leather bag, for example, might use material from a cow raised on a ranch in Brazil, where cattle ranching drives deforestation. As the cow lived, it burped methane, a potent greenhouse gas. When it was killed, the hide went through a messy tanning process that may have caused water pollution (chromium, a dangerous compound often used in tanning, sometimes leaks into drinking water).

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