I was doing a little plumbing yesterday and came across something I
hadn't seen before.
I cut a 1/2 copper pipe about a half inch from a sweated copper
coupling. Inside the pipe was small amount of green sludge, almost
like a drip, about 3/4" long. The sludge was soft and easily removed
from the pipe.
Was this nothing more than some flux that had seeped onto the joint
and reacted with the copper?