What solution to clean silver and gold contacts?


Hello!

          I am looking for a product to use to clean contacts in my audio system. Contacts are mostly gold plated, but some of them are pure silver on pure silver.
         I do not want anything that leaves any kind of residue / contact enhancement product. I read on forums that some members claim these products improve the sound at first, but later degrade it. So in the end, they removed all of the contact enhancement product from the actual contact.
         Right now I am mostly leaning towards using pure ethanol alcohol, as I think all of it would evaporate.
         Thanks in advance for all of your advices.
audiobb
Perchloroethylene also called tetrachloroethylene is very effective at removing hydrocarbons but not silver sulfide or metal oxides. Also it is a known carcinogen so care should be taken when using it. Although not as effective, ethanol is safer.
@ljgerens 

A question for you, please. I remove silver tarnish by putting the silver in electrical contact with aluminum foil, and immerse both in a hot solution of baking soda. The sulphate ion bonds to the aluminum, leaving the silver intact without pitting. Have I missed something?

Also, I understand that sulphates can be present on the fingers. Is this not correct?

Thanks!
An inexpensive option is to use Q-tips, jewelry clothes, and jewelry cleaner. This should be good for gold or silver and it is relatively safe.  
@ Terry9
This is a well known electrochemical reaction to remove sulfur from silver and form aluminum sulfide. I have not studied this myself but I believe it is effective. I cannot comment on whether or not micro pits form using this method. If it works for you and you have observed no adverse effects, keep using it.

Sulfur containing compounds can be present on one’s skin. Depending on their chemical composition they can react with a silver surface.