copper cable blackening problem 1

[incognito1]

i have faced a issue of copper cable blackening after few months of productions.

what are possible causes for copper cable blackening?

how can we prevent this issue during copper cable manufacturing?

 

[btrueblood]

Copper mostly turns black due to sulfur-containing compounds. Most typically, sulfur dioxide in the air (due to fossil fuel combustion), but also from contact with drawing compounds (greases) during wire manufacturing, and subsequent handling (even fingerprints).

Prevention would require making sure the wire is cleaned of greases/oils/salts then coating with a suitable paint or lacquer. A less long-lived method would be to apply a silicone oil or grease.

 

[incognito1]

Black is not visible during manufacturing. It is only visible after few months. Any preventive action to eliminate this issue?

 

[btrueblood]

What part of "most typically, sulfur dioxide in the air" and "coating with a suitable paint or lacquer" are not resonating?