The 6mm Pallo Steam Wand Brush is specially designed to clean out the inside of your steam wand (but it's also great for cleaning portafilter spouts!). Even if you're diligent about purging, mineral deposits can form on the inner walls of your steam wand, preventing a complete purge. A partial vacuum can be formed as your machine cools down, sucking milk up towards your boiler. Prevent buildup by cleaning your steam wand with Steamy Wanda!