Also, forgot to add...I had mold in the area, and sprayed the entire area with 100 percent bleach. It appears this could be the cause?

Its not mold, and To the best of my knowledge does not affect the integrity of the pipe.

ItÂs a common result of pipes that were not wiped clean after the installation with solder. The copper is an elemental metal and the acids used to flux the joint are fairly strong. When acid and metal react, they produce, chemically a salt. That explains the crystalline formation. It is hard to clean because the flux is a resin which forms a coating.

Also, for some years, the solders included lead  in trace amounts  which is a highly reactive metal. The presence of acidic flux is almost sure to produce some alkaline.

Basically, good old hot water, soap and elbow grease will clean the joints. As far as deterioration goes, it is unlikely, simply because the amount of reactant is so limited. On the other hand, issues have arisen in pipes that are not even this much compromised. It is hard to connect the two together: pinhole leaks. But, they do, sometimes, develop after years of use.

Pinoke

Thanks..this is a photo.

{{!gwi}}

Another one...bad looking, yes? Makes me want to change it out.

{{!gwi}}

Much better description, the pic. You can see from the pattern that what has happened is the reactant, whatever it is, began as a strip on the top and ran down in several paths. Because it did not run uniformly, it must be that the wetting of the pipe surface was modest, which suggests to me that the spraying you mentioned could be a cause.

But I am suspicious about that, too; because it seems that a spray would not settle on top and then drip. What would cause this is, if the pipes were chilled and then lay upward onto a source of moisture. Then, small amounts of moisture would create wetness along the top surface, and to some extent attempt to drip off.

But the drips themselves are very slight, suggesting that they actually dried out before falling to the floor. I will retract my first guess about flux and wiping. That occurs at joints only. Yours is occurring along the length of the pipe.

Since I donÂt know the cause, IÂm suggesting, contact with an occasionally moist source. But I think the discoloration is largely cosmetic. Try cleaning the surface with a mild acid: vinegar or citric. If it begins to clean the surface, you might want to try a stronger one, such as muriatic. Depending on the size of the task, you might want to use other means, such as abrasives more aggressive than the steel wool you tried.

In any case, you can decide for yourself how serious the problem is by learning how deep the corrosion goes. If it remains just a skin, that seems to be innocent enough.

Pinoke

I say moisture also. Think of how copper discolors when left outdoors

It appears to be the common "Patina" that forms on copper when exposed to moisture and some atmospheric elements..although some think it unsightly on copper pipes they would pay through the nose to get the same effect on a copper roof or statue in the rose garden...

From the motled pattern it is most likely a result of condensate moisture forming on cold water lines during hot humid summer days...its nothing to be overly concerned with.

one more picture...I tried several methods to clean, but emery cloth worked best. It was actally pitted underneath. Some flakiness/scaling in areas that had some dark maroon coloring underneath, then to shiny copper and pits. I smeared some black marker into the pits to enhance the picture. This concerns me. I remember an episode on This old house about pipes than can corrode from the inside out and also from the outside in (like my case). I do not recall the cause. Do you think it is more an issue now that pitting is apparent? It is a 1960's home, not sure if they used the light or medium wall copper? I do not think the spraying of bleach years ago would have caused this. Would moisture cause this and if so, would wrapping them stop this?

{{!gwi}}

At 46 years old the pipe is simply showing its age but the bottom line is,,"If it ain't broke, don't fix it" or in this case, if its not leaking don't worry about it.

Maybe it looks worse than it actually is?