Thanks Eric,hi J,
This is the best I can find..
E
https://www.google.com/search?clien...er+contacts#kpvalbx=_AMHxYLrfKYubgQbmxJbACQ61
Directly below the product there is also this description, which is exactly the materials I used.
Mix 1/4 cup salt, 1/4 cup flour and enough vinegar to make a thick paste. Use a soft cloth to rub the paste on the surface of the copper. Buff the copper item until it shines. Rinse with warm water and dry thoroughly.