I am trying to find out how to connect and seal a male copper pipe (from bathtub drain) to a female PVC coupling (to drain/sewer). The plumber that repaired the original, cracked coupling used a blue 'putty' to seal the M to F connection, but I used Drano to clear a clog and I think it ruined the seal.

Right now I am looking for the material he used to seal the M to F connection, as well as knowing if using the Drano ruined the seal that had been fine for 3 months.

This is a through the ceiling reapir, and I want to make sure this leak never happens again, since I will be repairing the ceiling in a few weeks. I am glad this happened before I closed up the ceiling.

Thanks in advance.