there are many methods people use. I have found lemon juice, diluted with a "little" water works well.Sit it in the solution,for a couple minutes,brush with old tooth brush,drop back in solution for minute or two,and repeat until desired affect.It is a quick and affective way to clean copper coins and buttons.BUT BEWARE!It is not hard to over clean stuff with lemon juice.You cant leave it and forget about it.you have to stay with it as you clean your item."Over cleaning" with allow the acid in the lemon juice to affect the metal itself.This process should not take any longer than 10 minutes.Be sure to rinse well with water for final cleaning,because without rinsing the acid in the juice is still active.You might want to practice with old pennies or something first.