Reverse sink overflow

[Karl E. Gerhauser]

Yesterday's home hand 2 cultured marble bath sinks with the overflow drain manually plugged. There are flow stains running down to the drain. I can come up with no scenerio to explain this. (Even a back-up problem should flow out of the main drain until the overfolw level is reached, right?) Has anyone dealt with something like this? Thanks in advance.

Cluless in Oregon

[Scott Gilligan, CMI]

Plunging the sink while there are chemicals such as drain cleaners can casue staining in those types of sinks if there is a lot of gunk in the overflow. It gets chemically etched into the surface of the sink.

[Karl E. Gerhauser]

Ding,Ding,Ding,Ding. Thank you Scott, my melon didn't go there. (79 others didn't either.) Thanks again, that is the only logical explanation, for the manual plugging also, not enough force with open o-flow.