When steaming milk and other liquids, always start with a clean, cool pitcher. This rule also applies when steaming by hand.   

Having a rincer close to the Perfect Moose is the ideal set up for the finest quality foam. When you have finished pouring your latte or other, give the smart pitcher immediately a rinse and you’re ready for the next. 

Letting milk stick after steaming is (A) not very tasteful, (B) not hygienic and (C) not good for the quality of your microfoam.