Our copper mug will frost up in mere seconds. The pure copper transmits an icy cold experience directly to your lips, and the metal locks in the drink's coolness. The inside of the mugs is unlined and made from pure copper, so some oxidation may take place, we recommed using any copper cleaner cream to keep your mugs looking like new. These Copper Mugs will really stand out in your kitchen and impress your friends. The shiny copper exterior glimmers wherever it is placed, and it's the perfect staple for the host or party-thrower. These mugs are externally lacquered to maintain the luster and last a long time unlike other mugs. Beautiful yet functional! Hand Wash Recommended. No nickel or stainless steel, Pure Food Grade Copper. These mugs are the real deal--drink the moscow mule the way it was meant to be enjoyed, with a handcrafted pure copper mug. Clean your copperware by hand and avoid dishwasher as the detergent can cause oxidation leading to permanent damage. Use Pitambri Powder for cleaning the copper utensils. More effective than traditional cleaners like tamarind, lemon. Completely safe and gentle on hands.