Those humble sheets of aluminum foil in your kitchen cabinet are composed of a fairly reactive metal. If you've ever left ketchup, lemon juice or any other highly acidic or basic food on a sheet of foil you probably noticed little black spots developing. These are little sections of dissolved aluminum. Acids like vinegar dissolve aluminum foil into aluminum salts. Aluminum salts are safe to consume if they accidentally get on your food. But dissolved aluminum is more commonly used to clean silver.
Mix 1 tbsp. salt, 1 tbsp. vinegar and 1 cup warm water in a glass beaker or dish. Stir well.
Add a piece of aluminum foil that is no more than a few inches on each side. Completely submerge the foil.
Leave the vinegar in the solution until it is dissolved. Or, add your silver jewelry to the solution and leave it for one hour to remove tarnish. The vinegar solution will only be reactive with the top layer of the aluminum foil. To dissolve the entire piece, take it out each hour and wipe the black layer off of the aluminum with a dry towel and replace the sheet for another hour.