Cleaning & maintenance

Salt, lemon, ketchup: Testing homemade copper cleaners



Can homemade recipes remove tarnish as well as a commercial cleaner?

Salt, lemon, ketchup: Testing homemade copper cleaners


Removing tarnish requires an acid; adding an abrasive helps the acid work more quickly and evenly. Commercial copper cleaners offer engineered combinations of acids and abrasives but you can put together a similar solution at home using table salt for the abrasive and ketchup or lemon juice for the acid.

I decided to test four tarnish removal formulas: tomato ketchup alone; tomato ketchup with table salt as an added abrasive; lemon juice alone; and lemon juice with table salt. I used two test subjects: a lightly tarnished lid and a gratin with heavier tarnish on its base. I then applied Bistro, my preferred copper cleaner, to see if it produced a different result from the homemade formulas.

I was pleasantly surprised: The addition of the table salt abrasive to either ketchup or lemon juice produced an effective tarnish remover. Both formulas worked quickly to dissolve tarnish without a lot of rubbing. However, when I compared the results against Bistro, the difference was immediately apparent: the homemade recipes left an uneven cloudy finish that Bistro removed, producing a clearer and more attractive result.

My recommendation to you is that either lemon juice or ketchup, with salt, is effective to remove tarnish quickly, but you will get a more even and thorough result from using a commercial cleaner like Bistro that is formulated for tough tarnish. You would also need to use these homemade cleaners regularly to prevent the formation of the deeper tarnish that they cannot remove.

My tests and detailed photo results are below.

Test Subject One: Lightly tarnished lid

This lid has what I consider a normal amount of surface tarnish.


First test: Ketchup, lemon, and salt

I divided the lid into four quadrants to test each method:

  • Upper left: Ketchup alone
  • Lower left: Ketchup plus table salt abrasive
  • Upper right: Lemon alone
  • Lower right: Lemon plus table salt abrasive

My methodology was to try to treat each quadrant the same: I massaged the substance in for about ten seconds and let them all sit for ten minutes.


I left the solutions in place for  few minutes and then rinsed and washed the lid with soap and water. Below are the results for the ketchup side and the lemon side respectively.


My assessment is that the thickness of the ketchup seemed to hold its acids to the surface while plain lemon juice seemed to sluice off. The addition of salt seemed to improve both of them dramatically, to the point where the results of ketchup + salt looked about the same as lemon + salt. I declared them joint winners of the test.

Second test: Compare to Bistro

My second test was to compare the results to Bistro, my preferred commercial copper cleaner. I applied Bistro to the section between the two winners (ketchup + salt on the left, and lemon + salt on the right). My goal was to get the Bistro-cleaned area right up against each of the other test sections so you can see the boundary clearly.


I thought the lemon and ketchup sections were pretty good until I saw them against what Bistro can do. The ketchup and lemon sections are uneven; the finish is cloudy and the tone of the revealed copper is redder, which may indicate additional copper oxides remaining on the surface. The Bistro section is clearer and more even and the revealed copper is lighter, which I suspect means that more copper oxide was removed.

Test Subject Two: Heavily tarnished gratin

My second test subject is an oval gratin pan that has seen fairly heavy use. It’s got more extensive tarnish on its base (as well as some polymerized oils, but they won’t yield to a mere copper cleaner!).

Salt, lemon, ketchup: Testing homemade copper cleaners
Detail of the tarnish

First test: Ketchup, lemon, and salt

As with the first test subject, I divided the gratin into quadrants.


As we saw above, the addition of salt improved the results dramatically. Again, the ketchup + salt and lemon + salt are the clear winners. (For the photos below, I moved to natural light to capture the surface texture details, as overhead kitchen lighting created too much glare.)

Second test: Compare to Bistro

I decided to run the second test a little differently from the same test on the first subject. I used the “winners” to polish the rest of their sides, so that the left half of the base of the gratin was all ketchup + salt, and the right half was all lemon + salt. The fact that you can see the boundary line between them means that there is a subtle difference in the results from each formula.

The completely cleaned base still shows cloudiness — patches of deep tarnish that resisted the ketchup and lemon formulas. I applied Bistro specifically to tackle this uneven finish, and the before and after below show that Bistro was effective in removing it.


These two test subjects produced the same results: with the addition of salt, both ketchup and lemon are able to remove tarnish quickly, but they did not seem to penetrate into the deeper layers of tarnish and leave cloudy areas behind.

Bistro, a commercial copper cleaner, is engineered to be an effective tarnish remover. It uses the same citric acid as in lemon juice and in a similar concentration: natural lemon juice is 8% citric acid, while Bistro claims to be 1-5% citric acid. But Bistro uses harder abrasives: table salt is Mohs 2, while Bistro uses kaolin clay (Mohs 2-2.5) and ammonium hydroxide (Mohs 9). These harder abrasives may make the difference here, though it should be noted that Bistro also includes solvents and detergents that may contribute to its effectiveness.

I think these home remedies are fine for quick and dirty tarnish removal, but they can’t tackle much more than that. You’ll definitely brighten up your copper and make it gleam but you won’t be able to dislodge set-in tarnish. For that, you’d need a commercial cleaner like Bistro. I don’t clean tarnish very often; I clean and polish my display pieces to preserve their shiny finish, but I don’t bother with my cooking copper. While this experiment was enlightening (I admit I doubted these home remedies and was surprised at the results), I plan to stick with Bistro and Simichrome polish to maintain the shine on my display pieces and to clean my working copper only sparingly.

If you want to keep your copper clean from tarnish, these homemade recipes are inexpensive and quick, but you would need to use them frequently. Otherwise, your pots will have the opportunity to form the deep tarnish that will yield only to a stronger commercial cleaner.

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