Hi JohnK,

Thanks for the chemical explanation and of course---duh, PVC, polyvinyl chloride, is where the chlorine factor comes in. I've said "PVC" for years without really thinking of the chemical composition.

So I think we can conclude that some PVC jackets become unstable and leach out chlorine, which reacts with the copper, producing the greenish color.

Regards,
Alan

Alan Lofft,
Axiom Resident Expert (Retired)