Have you been using dishwasher to wash your copper vessels? Don’t! Do these instead.
Copper may oxidise and lose its lustre and darken with time. Two easy and all-natural approaches are suggested for taking care of your copper utensils:
It is possible to use salt in addition to lime if more polishing is required. After spraying the object with lemon or lime juice, sprinkle salt on the copper. Use a delicate cloth to massage onto the copper surface.
After applying the salt, make sure to thoroughly scrub the whole dish with the towel. A reaction may occur and black stains may emerge on the copper if the salt sits on it for too long. Once you've scrubbed and rinsed the item to your satisfaction, towel it off with a soft, dry cloth.
Use the tamarind paste to coat the copper object completely. Give it 20 minutes to soak into the copper object. In this case, letting the tamarind dry on the copper is OK. After waiting 20 minutes, wipe the dried tamarind paste off the copper using a soft sponge. You should wash it with water and dry it off with a towel.
You may use the tamarind water to clean the interior of copper bottles and other containers. Be careful to use enough tamarind water to completely saturate the sides. Wait 20 minutes before washing out. After twenty minutes, you may scrub the interior with a brush to remove any remaining sediment. Use warm water to wash and dry off with a soft towel.