Have used wall filler to secure copper pipes into wall, but the filler has turned blue. Is the filler corroding the copper?
It might be the reverse: copper oxide is blue; if moisture (why, pray tell?) is present, then the filler might react with the copper pipe. I have no experience with this situation, sorry.
It's the other way around, it is a verdgris reaction on the copper. Verdigris is a variable chemical mixture of compounds, complexes and water. The primary components are copper salts of acetate, carbonate, chloride, formate, hydroxide and sulphate. The secondary components are other metallic salts, acids (organic and mineral), atmospheric gases and water. It'll probably turn green later. When green it is stable.
