The Moscow mule is the rare cocktail where the vessel is part of the recipe. Copper conducts heat roughly twenty times better than stainless steel, so the mug drops to the temperature of the drink almost instantly and frosts on the outside. That is not marketing — it is why the drink has been served this way since the 1940s. What that means in practice is that the copper needs to be on the outside, where your hand and the air meet it.
Solid, plated, or lined?
There are three constructions on the market. Solid copper is a single sheet formed into a mug. Copper-plated steel has a thin copper layer over a stainless body. Lined copper is solid copper on the outside with a stainless or nickel interior.
Solid copper gives the strongest chill and develops a patina over years, but it needs regular polishing and puts bare copper against your drink. Plated and lined mugs keep the copper exterior — and most of the visual appeal and outside frost — while the liquid sits against stainless steel instead.
The lining question, answered plainly
Lime juice is acidic, and prolonged contact between acidic liquid and bare copper can leach copper into the drink. The important word is prolonged. A mule that is mixed and drunk within the hour is not the scenario health guidance is aimed at, and unlined copper has been used for decades. But it is why lined mugs exist, and why most bars that leave drinks standing use them.
If you want the question off the table entirely, choose a mug with a stainless interior. You give up a little conductivity and the ability to re-polish the inside; you gain a mug you can fill with citrus and not think about.
Which one should you buy?
Buy solid copper if you care about patina, polish your barware, and want the absolute coldest mug. Buy copper-plated with a stainless lining if you want the look and the chill without the upkeep or the acidity question — which, for most people entertaining at home, is the practical answer.
Whichever you choose, check the handle joint. A riveted or properly brazed handle survives years of use; a spot-glued one does not. And check the hammering — machine-stamped dimples are perfectly uniform, hand-finished ones are not, and the irregular ones age better.
Sizes and how many
The standard mule mug is 16oz / 450ml, which fits the classic build of vodka, lime and ginger beer over ice with room left. Buy in pairs — mules are a sociable drink and a single mug gets used far less than a set of four.
Care
Hand wash, dry immediately, never the dishwasher. If the exterior dulls, lemon and salt restores it in under a minute. Some owners deliberately let the patina build; both are correct.
Ours are the second kind: a copper-plated exterior over a 304 food-grade stainless interior, in 1, 2, 4 and 6 packs from $16.95 with free worldwide shipping. See them in the copper drinkware collection.
