Used Liquid Plumr drain opener in Bathroom Sink to unclog drain over a year ago. Had mixed results and unfortunately burned my hands after flushing sink with water. Apparently there was Liquid Plumr residue still in sink. Someone suggested I use a pumice stone to remove residue. It worked well but unfortunately the shavings created more of an obstruction in drain. (If I had known this would happen I would have been careful to remove shavings). Had professional plumber clear drain with snake. This seemed to work well as sink drains without any problem. Unfortunately there is a residual odor of Liquid Plumr whenever I run the water. I've done my best to scrape away the residue of Liquid Plumr within five inches of drain opening and tried flushing sink several times with hot water for as long as twenty minutes but problem remains. Worried that residue further down is causing problem and not sure what to do. Will flushing sink with water eventually take care of problem or is something more drastic required? Also concerned that some shavings of the pumice stone remain in drain and are contributing to problem- i.e., would shavings make it difficult for residue of Liquid Plumr to be completely flushed out?