in italy we are cleaning copper with a different mix, which is also chemical-free. we mix some vinegar with 'powder' salt, not coarse salt to prevent scratching. you can put salt directly on the object to clean then add the amount of vinegar to make the salt dissolve (a couple of spoons) and rub on it.
Jul 14, 2020 · Fill a container with enough vinegar to completely submerge the jewellery. Then place the piece into the container. Allow the jewellery to sit for approximately 20 minutes, then remove the piece from the mixture. Use a cotton swab or a toothpick to remove loose pieces of verdigris form the jewellery.