As an alternative to single-use plastic wrap and paper cup coatings, researchers in ACS’ Langmuir report a way to waterproof materials using edible fungus. Along with fibers made from wood, the fungus produced a layer that blocks water, oil and grease absorption. In a proof-of-concept study, the impervious film grew on common materials such as paper, denim, polyester felt and thin wood, revealing its potential to replace plastic coatings with sustainable, natural materials.