How Copper Pots Are Made

An expert shows how this classic cookware is spun on a lathe, tinned, and finished.

In ancient times, copper was worked by hand with a hammer. But most copper pans aren't made that way today—it's simply too laborious. That leaves two preferred methods for creating most pan shapes: spinning on a lathe or forming in a press. On a visit to Duparquet Copper Cookware in Rhode Island, owner Jim Hamann (who also runs a restoration service called East Coast Tinning) showed us how he spins his pans and even let me join him on the lathe to make a couple of saucepans. In the video below, you can watch the spinning process from start to finish.

Spinning Methods

Spinning copper begins with a blank disc of metal, which is set on a lathe next to the chuck—a form that determines the size and shape of the pot. As the lathe spins, the copper is pressed with a roller that gradually bends it over the form until the metal has taken on the desired shape. Jim uses three-millimeter discs of copper (considered by many to be the ideal thickness; read more about that in our copper cookware guide), which are relatively thick and therefore harder to bend. Because the roller's pressure and speed are controlled manually, spinning copper requires training and skill; using uneven pressure and speed can produce a wonky pot or pan with uneven, lumpy sides.

When I spun pans with Jim, he manned the lever that applied pressure, while I operated the one that controlled the roller's speed and direction. It was a challenging process: The lever I held would shift unexpectedly, first pushing toward me and then suddenly pulling away. If you don't react quickly enough, you can send the roller skittering off. To spin a pan well, the roller should move at a consistent pace, but when the lever shifts, that can be difficult to control. And that only pertains to the speed lever—Jim, who has all the experience, put himself on the pressure lever, since it's the more difficult of the two to operate properly.

Pressed copper, on the other hand, requires almost no skill: manufacturers simply place a blank of copper on a form, press a button, and watch as a mechanical arm descends, forcing the copper down over it. There's no real quality difference between spun and pressed copper cookware, but producers like Jim, who do still spin, pride themselves on using this more demanding technique.

Some copper pieces are neither spun nor stamped, but rather rolled. In those cases, sheets of copper are rolled or bent into position by hand, and then the seams are joined. This method is sometimes used for large stockpots or unusual pan shapes like boxy fish poachers; the presence of seams is not a sign of lower quality.

You're also likely to encounter copper pots and pans with hammer marks on them. Once upon a time, this might have been a sign that someone pounded the pan by hand to form, harden, and strengthen it (striking copper hardens the metal after it's been softened with heat), but today those hammer marks are almost always done by machine as a decorative gesture. They're an aesthetic detail and nothing more.

Attaching the Handle

Regardless of method, it's time to attach the handle or handles once the copper vessel is formed. In most cases, the handle is mounted with copper rivets, which are placed through drilled holes in the handle and pot, heated until softened, and then hammered into place. With each hammer blow, the metal hardens a little more. By the time the rivet is nice and tight, the metal is also hard enough to keep the handle in place.

Handle materials vary. Brass has passed in and out of favor, though cast iron is among the most common and traditional. Cast iron is a sensible choice since it doesn't conduct heat as well as copper, slowing down the rate at which the handle becomes too hot to touch (it will eventually get hot, though, so take care and use a towel or mitt).

Lining the Inside

The final step is to line the inside of the pan, since copper is a reactive and toxic metal and a lining limits how much food comes in contact with the copper. Many manufacturers today bond a stainless steel liner to the copper shell. Stainless steel offers the benefit of indestructibility—you can abuse it, scour it, do whatever you want to it, and not too much will come of it.

Traditionally, though, copper pans were lined with tin, and that's what Jim does. Tin is a softer metal that's more prone to damage; eventually all tin-lined copper pans require re-tinning. On the upside, tin is a naturally nonstick metal, making it more of a pleasure to cook on than stainless steel, which sticks to foods much more. Tin requires more care, though, so it's worth reading our primer on how to properly use and clean copper cookware to make sure you don't do any unnecessary damage to it.

One of the main risks with tin is melting: Tin has a relatively low melting point of 450°F (232°C), a fact that helps explain how it's applied to the inside of a copper pan. The copper is set over high heat, and then pure tin is melted into it. A few deft swipes and strokes with a piece of cloth create a thin, even coating. (To prevent tin from getting on the outside of the pan, a protective coating is painted on and then washed off after.)

Of course, that low melting point means you can accidentally melt the tin at home. For this reason, you should make sure not to heat a tin-lined copper pan empty, or you'll be sending it to a re-tinner for repairs. Tin-lined pans all need to be re-tinned eventually, but there's no reason to have to do it prematurely if you can help it.

As for me, I'll stick with my day job. It was a ton of fun to make pans with Jim, but the ones I helped him spin weren't quite good enough to make it to his showroom floor. On the plus side, I now have a slightly imperfect saucepan for all my fancy sauce-making. Maybe I should go back and mess up some more of his pans...

January 2019

Read More

• The Pros and Cons of Copper Cookware

• How to Clean and Care for Copper Cookware

Read the original article on Serious Eats.