Minecraft wiki entry for Cauldron, associated text: Powder snow is currently the only solid material which can be stored in a cauldron. A cauldron slowly fills with powder snow during snowfall, if starting empty or with any layer of powder snow already inside. Up to three layers can be filled. When the cauldron is full, interacting using a bucket, will create a powder snow bucket and empty the cauldron. Entities standing in the cauldron will not take freeze damage, and entities wearing leather boots will still fall through the powder snow.