If you hope to be a discerning buyer of copper cookware, you must know the terms for the different types that are out there.
Copper as the primary material
These pans are made principally of pure copper with one other metal present only as a single thin inner lining.
- Straight-gauge copper is made from a sheet of pure copper with a very thin lining of tin or nickel (or rarely, aluminum, though I’ve never actually seen one).
- Copper bimetal is a sheet of pure copper fused to a thin lining of stainless steel that makes up no more than .2mm to .3mm of the total thickness.
Vintage copper is all straight-gauge; copper bimetal didn’t come on the market until the 1970s. These are the only kinds of pans I talk about on this site.
Copper as a layer in a sandwich
Multi-layered cookware combines some of the benefits of multiple metals while providing a resilient inner stainless steel cooking surface. However, if there is a layer of copper, it can be quite thin — 1mm or less — and while manufacturers are happy to tout the presence of copper, they are reluctant to disclose the exact (often trifling) amount.
- Tri-ply, multi-ply, or clad refers to cookware with three or more layers of metal.
- Copper core refers to multi-ply or clad cookware with a layer of copper intended to provide the “core” thermal behavior of the pot.
- Copper clad refers to multi-ply cookware where the outside visible layer is copper, but does not necessarily imply anything about how thick that layer actually is.
Copper as a layer on the bottom only
Another construction method is disc-based, where the pan has a thick circular base made up of layers of metal and walls of thinner stainless steel. As with clad and ply cookware, the disc can be made up of various combinations of copper, aluminum, and stainless steel, but disc-based pans can incorporate thicker layers of metal than would be tolerable in ply or clad construction.
When “copper” is not copper at all
Copper-colored “nonstick copper cookware” or “ceramic copper cookware” doesn’t have any copper metal in it. The pans are aluminum with a non-stick copper-colored coating. This paint does not confer any of the benefits of copper metal and it’s misleading for manufacturers to use “copper” in the product name.
I’m trying to be non-judgmental here, but it drives me bananas when people rave about how much they love “cooking with copper” when they’re using these pans. It’s not copper.
For further reading
This site is about straight-gauge and bimetal copper pans, but if you’re also interested in other kinds of cookware I am happy to direct you elsewhere.
For much more on the science of how all these different metals perform during cooking, I direct you to Cooking for Engineers and their excellent post Common Materials of Cookware.
For passionate arguments about the merits of these metals and cookware construction methods, check out Chowhound’s Cookware forum.
For numbers on the thickness of layers in a specific product line of cookware, please see CenturyLife’s Cookware Thickness Database. (Much of that info is not published by manufacturers.)
For some thoughtful guidance on choosing cookware, I suggest you explore CenturyLife’s How to Choose Cookware area and dig into the in-depth reviews and comparisons of specific pots and pans.