copper cable getting blackened in cable manufacturing

[isurunalaka]

hi, does any one know why copper cables are getting blackened after some time of cable manufacturing? are there any ways to prevent this issue?

 

[srizbf]

blackening in copper or in sheath?

 

[isurunalaka]

blackening in copper

 

[srizbf]

blackening in copper

there may be many reasons why a copper turns to black.

sometime you may not be able to solder to the copper as it was in nonblack state.

manytimes it is identified as sulphur causing reaction.
exposure to that atmosphere is one cause.
it will smell bad when it is black.

even if it is not in that environment , the raw copper sourced for manufacture may contain that as impurity.

 

[chuckey]

The black on old copper cable is due to sulphide or oxygen reactions. That is why the majority of cables are tinned plated. Old rubber covered cable was very bad for this, as sulphur was used in the process of making rubber. I have found that the only way to solder these old blackened cables is to scrape the black off, ordinary solder flux does not touch it. Acid based (plumbing) flux might clean it off but will lead all sorts of other problems.
Frank

 

[Audioguru]

The insulated wires in my very cheap Chinese solar garden lights turn black and are impossible to solder. The rain leakage and humidity caused it. My replacement wires do not turn black because they have some quality.

 

[isurunalaka]

what is the reason for quality change

 

[Audioguru]

what is the reason for quality change

The wires from China have very poor quality. My American replacement wires have excellent quality. The Chinese wires turn black and the American wires stay like new.

 

[isurunalaka]

what property in cable accelerates blackening?

 

[Audioguru]

I think the insulation has a high sulfur content, maybe from real rubber.