It is not compulsory. Not all heat transfer ceramic mugs and ceramic plates should be cooled in cold water to prevent the ink from continuing to evaporate. As long as the heat transfer materials is removed from the heating plate, the inks won’t be continued to evaporate. Therefore, both cooling naturally and by clod water is available. In addition, some ceramic mugs and plates with low expansion coefficient will be burst after throwing into cold water, especially in Winter. Only in the condition that the ceramic mugs and plates must be cooled by cold water, they can be thrown in nature cold water in Summer and in warm water in Winter.