Paint Cans (Empty) Put in Garbage If your paint can contains less than 2 inches of paint, open the lid and let the paint dry. After the paint is dry, you may then place the container in the trash. Dry Out and Throw Away Make sure paint cans are completely empty and dry. Throw them away with the lid off because this shows that the can is completely dry. Keep If Not Empty If the can is not entirely empty, store it for future use. Once a paint can is opened, it will last for two years, but an unopened can of oil, acrylic or latex paint can last for over 10 years.