Things You'll Need
Citric acid has long been known as an effective, mild cleaning agent for removing tarnish and discoloration from metal. It is especially good at removing discoloration from the surface of copper metals, such as cooking pots and utensils. Food grade citric acid is produced naturally in most citrus fruits such as oranges, lemons, grapefruits and limes. Citric acid is also available for purchase in bulk quantities from food suppliers and restaurant supply companies.
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Clean the copper item using soap and water to remove as much of the external dirt and debris as possible. Citric acid is great at removing oxidation, but poor as a cleaning solution so you want a clean item to start with.
Dry the copper item with a clean towel.
Pour a solution of pure lemon juice into a container large enough to place the copper item into. Place 1 to 2 tsp. of plain table salt into the container. Use a spoon to stir the lemon juice well and completely dissolve the table salt.
Place the copper item into the lemon juice. If the item is too large to submerse into the liquid, you can simply apply the lemon juice liberally to the surface of the object using a cloth soaked in lemon juice.
Allow the item to sit in the lemon juice for 60 seconds.
Remove the copper item from the lemon juice and rub it with a clean, dry cloth. If the tarnish is difficult to remove, use a scrub sponge instead of a cloth. The oxidation and tarnish should easily rub off onto the cloth.
Rinse the copper item in plain tap water to remove all traces of the citric acid.
Dry the copper item with a clean, dry cloth.
Do not allow the citric acid to sit for more than 60 seconds on copper items as it can lighten the color of the metal if left on for too long.