Legitimately manufactured food-grade packaging papers (such as baking paper and edible rice paper) are certified for food safety and can come into direct contact with food. If a paper emits a bluish-white glow under ultraviolet light, it may contain fluorescent agents. While standard paper packaging is unsuitable for microwave use, silicone-coated paper or baking paper labeled "microwave-safe" can be used for short periods (recommended limit: 2 minutes). Metal-coated packaging paper must not be used in the microwave. Unopened food packaging paper typically has a shelf life of 2–3 years. Once opened, it is recommended to use the product within six months; it should be sealed to prevent moisture absorption and the uptake of unwanted odors. Standard food packaging paper is classified as recyclable waste but must be cleared of food residue before disposal. Composite packaging papers containing aluminum foil or plastic coatings should be disposed of as dry waste.