How to Remove Copper Foil Oxidation

Fill a bowl with white vinegar and add three tablespoons of table salt. Slowly add flour to the mixture, stirring it in with a paint stir as you go until it thickens into a paste.

Apply the mixture to the affected areas of the copper foil using a rag. Let the mixture sit on the oxidation site for 30 minutes.

Scrub the affected areas of foil in circular motions using a soft-bristled toothbrush until you reveal the copper's original shine. If the foil is thin, rub slowly and carefully to avoid tearing it.

Rinse the vinegar mixture off the copper with clean water. Thoroughly dry the copper with a towel. Any water spots left on the copper causes it to oxidize again in those areas.