Copper Mugs and Moscow Mules: Lovely, but Check the Lining

A copper mug beaded with condensation is one of those objects that just looks right, and there's real appeal behind the Instagram shine. But copper mugs come with one genuine catch that the adverts never mention, and it happens to involve the very drink they're famous for. Here's the honest picture: why they're lovely, the safety point that actually matters, and how to use them so you get all the charm and none of the worry.

Why copper mugs are lovely

Two things make copper mugs a pleasure, and both are real. The first is the way they feel. Copper is one of the best heat conductors there is, so a chilled copper mug takes on the temperature of an icy drink almost instantly and feels wonderfully cold in the hand, frosting up on the outside as it goes. The second is simply that they look beautiful, with a warm glow when polished and a soft patina as they age. For a summer cocktail or an iced drink on the table, they turn an ordinary serve into a bit of an occasion.

What they don't do is keep a drink cold for longer. A bare metal mug swaps heat with the room quite happily, so an insulated tumbler will out-last it. The copper mug is about the immediate icy hit and the look, which for a drink you'll finish in twenty minutes is exactly right.

The safety catch worth knowing

Here's the part that matters. Copper reacts with acid, and when acidic liquid sits against bare copper it dissolves a little of the metal into your drink. Too much copper isn't good for you, so this is worth taking seriously rather than shrugging off.

The irony is hard to miss. The drink most associated with copper mugs, the Moscow mule, is one of the worst things to put in bare copper, because both the lime juice and the ginger beer in it are acidic.

The reassuring news is that this is a solved problem. Most copper mugs sold today are lined on the inside with stainless steel or nickel, so the drink never touches the copper at all, and those are perfectly safe for a mule or any other acidic drink. The copper is on the outside, where it belongs, doing the job of looking good and feeling cold.

Lined or unlined: how to tell, and what to buy

The whole question comes down to the inside of the mug.

Lined copper mug	Unlined copper mug
Silvery stainless steel or nickel interior	Copper-coloured inside and out
Safe for acidic drinks, including Moscow mules	Keep for water, spirits or display only
The interior stays bright and easy to clean	The inside tarnishes like the outside
What most modern copper mugs are	Often older, cheaper or purely decorative pieces

When you're buying, look for a mug that clearly states a stainless steel or nickel lining, and check the photos show a silvery interior. As with copper cookware, make sure it's genuine copper rather than a copper-coloured coating over another metal if you want the real look and feel. If you already own copper mugs and aren't sure, treat any that are copper-coloured on the inside as unlined, and save them for non-acidic drinks.

To keep them lovely, wash by hand and dry promptly, bring back the shine on the outside with lemon and salt or a little bicarbonate of soda, and give any drink, especially an acidic one, a rinse out rather than leaving it to stand. Look after them and they'll still be turning heads on the table for years.