Had a jar of old coins in the shed for years so finally decided to clean them up. All common post war coins of little value.
Google suggested a solution of vinegar/acetic acid and salt. I used kettle descaler and salt which bought the copper coins up lovely. Then I tried the same with 'silver' coins. Five minutes later I found they had all taken a copper sheen! Obviously I was foolish to use the same solution that I had cleaned the coins in as it appears the dissolved copper oxide had converted onto the silver coins. Not a chemist so do not know how.
So....how to I remove that very thin copper coating?
Google suggested a solution of vinegar/acetic acid and salt. I used kettle descaler and salt which bought the copper coins up lovely. Then I tried the same with 'silver' coins. Five minutes later I found they had all taken a copper sheen! Obviously I was foolish to use the same solution that I had cleaned the coins in as it appears the dissolved copper oxide had converted onto the silver coins. Not a chemist so do not know how.
So....how to I remove that very thin copper coating?