Resin prints can be cleaned in an ultrasonic cleaner two ways: The ultrasonic cleaner can be filled with an indeterminate mixture of water and a degreaser, such as Mean Green. This method may be cheaper but it results in a considerable amount of contaminated water. Alternatively, the ultrasonic cleaner could be filled with only water. The resin print, along with 91% IPA, is placed into a plastic zipper bag. The bag is slowly lowered into the water before closing the zipper. This will remove most of the air from the bag. This process is relatively safe and was documented by NASA over 50 years ago.