In an interview on the Kaufmann Mercantile blog, Mac Kohler of Brooklyn Copper says:
My go-to recipe for polishing copper is equal parts kosher salt and ketchup. Squeeze out a big glob of ketchup and add salt in equal measure. Spread the solution on the copperware and work it with a soft cotton or hemp cloth--not polyester or synthetics, as that will scratch the surface. Buff it out with another natural soft cloth. If you have dark spots on your copper, it is likely a carbon stain from cooking something starchy, like pasta, The water has been taken out of the carbohydrates, creating just carbon, which is black. Carbon and copper bond easily and these spots require a stronger commercial solution. If they don't come off, they need to be mechanically buffed, essentially breaking off the carbon on the copper surface. I've heard of people using a shoe buffer or an orbital sander with a buffing attachment.
I gave it a try on my favorite copper tart tatin pan (which I use for many other things besides tart tatin!) and it worked pretty well. The pan still had dark places here and there but like I said, I'm not interested in brand new, shiny penny look. And I loved the fact that I could whip this together with some very basic kitchen ingredients that also are non-toxic.
→ To read the entire interview with Mac Kohler, visit the Care for Copper post on the Kaufmann Mercantile site.
Do you have any copper cookware? How do you clean it?
(Image: Kaufman Mercantile)