Primeware uses a thin sheet of PLA and in essence "melts" it onto the bagasse. When faced with hot or greasy foods, unlined sugarcane bagasse containers can leak. But PLA creates a complete moisture and grease barrier. PLA is derived from plant-starch material, which means that it is fully compostable and able to biodegradable in a composting facility. Designed for to-go foods, PLA-lined products offer protection from stir-fried foods and dishes with hot sauces. Microwave & freezer safe!