For unfortunate reasons not worth dwelling on, my oak cutting board was left in the sink for a period of time with a silicone pot holder on top of it. When I discovered it, it had a big dark stain where the pot holder was sitting. Does anyone know how to remove this? I've applied a paste of Oxi-Clean, because this has worked in the past to remove stains from plastic cutting boards. Right now it's sitting with the Oxi-Clean paste on it. I can't tell if it's working. Any help would be much appreciated.