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
CAIG DeOxit and ProGold are the defacto standard.
http://caig.com/
Gold should remain bright it's entire life and not require cleaning - if it is dull it is not gold

Silver contacts just require re-seating to restore perfect contact.

I have had silver contacts on all my plugs/connectors and I am yet to see any signs of tarnish.

We have some silver ornaments that require constant cleaning and cleaning frequency got worse once we cleaned them.

My preference with audio connectors is to avoid cleaners completely -  I do not need shiny connectors

Just my approach - Steve

Gold does not oxidize so wipe gently with a soft cloth (not paper towel). Silver? Use a product called "Tarn-X". This chemically changes silver oxide (tarnish) back into silver. Works well on copper too...
Tarn-X will cause pitting of the object's surface. These surface defects will act like a sponge and more readily absorb tarnish-producing gases and moisture. The object will eventually require professional polishing to restore the original finish. Tarn-X is made up of acidified thiourea (a known carcinogen).    http://www.hermansilver.com/tarn-x.htm
rodman99999: You may be right. I always clean off the tarn-x with alcohol when finished. I've been using 25+ years and have not seen any pitting. BTW, I'm pretty sure the air, in an urban environment, has cancer causing substances. I lived in a Chicago house for 35 years whose shingles were pure asbestos (and flakey too). I'm sure mine wasn't the only one. Not trying to scare you or anything...
@dweller - My post was simply a quote, from the cited article(close to the end). Happy listening!
AudioQuest told me directly that tarnish on their silver-ended wires has zero impact on sound.  I've found that their silver-ended cables do tarnish slightly over a good amount of time (it IS silver), and if for some unusual reason after a good while I have them off and it's convenient, I'll remove the tarnish with a standard silver polish (Wright's Silver Cream)--very easy to do.  Of course I'm meticulous about being sure every trace of the polish is removed before reinserting.  But based on their guidance, I don't really care about it and could go probably indefinitely without paying attention to it.
FYI: Silver oxide is a better conductor of electricity than clean copper.
Silver does not form an oxide layer. In fact it is very difficult to oxidize silver under ambient conditions. The black tarnish is silver sulfide which affects the conductivity. Depending on the amount of sulfur in your local environment, silver can form a mono layer of silver sulfide in a matter of minutes. 
Thank you all.
It seems that everyone agree that tarnish layer is silver sulfide, that does reduce conductivity, and therefore can affect the sound.
I prefer to clean it with something that does not leave any layer behind.
Would alcohol remove the silver sulfide?
Or at least, clean the contact from the dust safely?
What can remove it, without leaving anything behind?
ljgerens, are you sure that silver sulfide can form in minutes?

Unless you’re living in a Sulfur-rich environment(ie: around volcanoes/chicken coops/sewage treatment plants), you needn’t worry about sulfites forming in, "a matter of minutes"! https://www.powellind.com/sites/downloads/ProductAssets/01.4TB.080%20Switchgear%20in%20a%20Sulphur%2...Various conductivities/causes, concerning oxides/sulfides, discussed here: https://forum.audiogon.com/discussions/dielectric-grease-on-connection-ends/post?postid=1381403#1381... BTW: What stanleylocke and williewonka said, +1(each) 
I did this experiment back in the 90s with silver in upstate New York. We exposed clean silver prepared in ultra high vacuum to ambient atmosphere for various lengths of time and found a monolayer of silver sulfide formed between 5 to 10 minutes. A monolayer should not affect conductivity and it is not visible to the naked eye but it shows how quickly silver sulfide forms. You do not need to be near volcanoes, chicken coops, or sewage treatment plants to have sulfur in the atmosphere. If your silver tarnishes there is sulfur in the air. When the tarnish is visible, thousands of layers of silver sulfide have already formed. 

Alcohol will not remove silver sulfide. you need an abrasive cleaner. The problem is when you use these abrasive cleaners they can pit the silver on a micro scale which makes the silver surface more reactive with sulfur.

All cleaners will leave a layer of something behind. Even alcohol will leave a layer of hydrocarbons on the cleaned surface, that is unavoidable. 



I forgot to mention that you can use a chemical cleaner to remove silver sulfide. These chemical cleaners are acidic formulations that are not supposed to be abrasive but still etch and pit the silver surface on a micro scale and are not really environmentally friendly or good for your health. I would not recommend them.
BTW: Silver WILL form an oxide layer, as long as the, "ambient conditions" are below 195 degrees Celsius(almost twice boiling), and - the atmosphere contains Oxygen: https://study.com/academy/lesson/silver-oxide-formula-decomposition-formation.html
I should have said silver metal does not readily form an oxide layer in air at room temperature. There is some oxidation but it is slight in comparison to sulfide formation.
the best is perchlorethylene ilquid
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.