This gives a slightly firmer and more persistent creama and you avoid the burnt tones associated with boiled coffee.The mettalic tang should disappear quickly if you just rinse and wipe it after use - Soap is a no no, but in order for this to work you have to use it frequently - almost daily - otherwise the thin layer of residue will go stale and taste bad. I have to brew 3-4 times after a week of vacation before the coffee is drinkable.