Compostable paper is paper that can be broken down by microorganisms into nutrient-rich compost. However, paper products that are coated with plastic or wax cannot be composted. These materials do not break down and can contaminate the compost, rendering it unusable for gardening and farming purposes. Additionally, paper that has been contaminated with food waste or other organic materials may not be suitable for composting, as it can attract pests and emit unpleasant odors.