I was going to post a recipe today. Very “garden fresh and organic!” and all that.But instead there’s all this buzz about copper: copper Moscow Mule cups, copper cookware, unlined copper.

And before there’s yet another article published that cites the same source or two, I thought I’d throw my hat in the ring as an American coppersmith and copper cookware manufacturer. I bend copper using tools from the 1800’s, I apprentice under a master smith, and I can tin my copper pots. Suffice to say, I touch a lot of copper.

So first and foremost: copper itself, in the proper amount, is not poisonous.

In fact, it’s a micro-nutrient the World Health Organization says everyone needs to live and many of us fall short of our daily dietary intake. (Sources: US National Library of Medicine National Institutes of Health, Copper Development Association UK/ CDA Inc (USA). Copper is safe in the proper amount.

There are two exceptions to unlined copper: Jam Pans and Bowls. Jam pans are not lined at all because of the science that goes with the sugar process that happens during cooking jam. Bowls aren’t lined because of the science that goes with egg whites and the fact that you’re not heating them.

But COOK with acidic foods in unlined copper? I’m the first to tell you it’s not safe.

That means using unlined copper with tomatoes, many kinds of hard alcohol, limes and lemons, wine, and the like is a big no-no. (Here is a really lovely chart showing the alkaline and acidic nature of many foods and drinks). Copper is reactive, releases copper molecules easily, and too much of a good thing is never…good.

Copper gets a tricky reputation because we all apparently have long memories when it comes to it (because it was the first metal we really utilized as Neolithic farmers, perhaps…). Some people talk about copper and lead in the same sentence, and that’s also true – back a LONG time ago, copper cookware pieces were held together with solder (“metal glue” as my kids call it) that contained a lot of lead, so people would eventually get lead poisoning. Thankfully, we’re all wiser, and now solder for old cookware repairs are 100% lead free.

And thankfully we’ve learned to line our copperware with something.

The Moscow Mule mugs out there – if they’re silver on the inside – are usually made from stamped/formed/spun aluminum or stainless, with a thin coat of copper on the outside for looks…or even copper paint! Why? Because it’s cheaper and easier to do that than to actually use pure, real, solid copper. These mugs are readily available and relatively inexpensive to make if you’ve got a factory to spin ‘em. So you’re not actually drinking out of a copper mug, but a stainless or aluminum one just dressed up to look like copper.

(How to know if it’s aluminum and not real copper? Pick it up – it’ll be really lightweight! Stainless will be a bit heavier but you’ll also see the circular spinning marks inside so you know it’s not tin or nickel.)

Sometimes you’ll find real, pure copper mugs lined with tin (we do it, but we do it by hand – there’s no other way to tin something), especially vintage pieces. And yes, I know we have the unlined version in the shopping list. I have to tell Bob that he might want to take it off. He has received orders in the past for people who want unlined copper drinking cups – they leave the water (a neutral! no pH!) in the unlined copper overnight and drink it in the morning, believing the copper to have purified the water due to its antibacterial properties.

Something else that I want to point out – there are several articles that mention using nickel as a lining. That’s totally true and possible to do as the two metals bond, but there’s a reason most of us cookware makers don’t line the copper with nickel much any more – if at all – (and this is true for American coppersmiths as well as the many over in Europe) and that’s because of nickel allergies. If you have a nickel allergy, make sure your copper cookware is lined with something else.

Nearly all copper should be lined.

It can be stainless steel, tin, nickel, silver, (heck, gold would bond as a non-ferrous metal) and even ceramic in some cases.

And while there are endless debates on which type of lining works best for copper cookware or even copper moscow mule mugs, as long as you don’t see any copper where you’re putting food or booze, you’re just fine.

Bottoms up!

PS – this article on Refinery29 is also really great on this super current topic.