Hello.  

What chemical to dip/apply to 50 year old ~10mm copper cable ends that are blackened from age to leave them copper bright again  ?   I removed the main feed to the circuit breaker panel and would like to use the opportunity to put them back 'pretty' 

Images borrowed from the web.  Mine is much darker but not greenish.  

Any mild acid should do the trick. Vinegar, lemon juice or ketchup.

Obviously, Coca-Cola.

 

I wouldnt treat with any chemical, because corrosion will take place into the wire. This can cause overheating and probably also fire , depending on the current. The best is to cut and strip the wire again, if length is long enough. Or use cable lugs crimped or soldered.

8 minutes ago, Sensei said:

Obviously, Coca-Cola.

 

 

Edited September 9, 20241 yr by chenbeier

If you plan to use them for electrical conductors you should heed Chenbeier's warning.

If you just want them clean, then sandpaper or vinegar are  good options.

If (it's a long shot) you plan to make sculptures from them then you might also want to anneal them.
Doing that involves heating them red hot and will generally leave them covered with a black oxide layer.

But if you drop the wires into a jar containing alcohol while they are still hot, the vapour will reduce the oxide back to the metal.

Obviously, be careful not to set the alcohol on fire.