Hello, my problem is driving me nuts. I just bought a home and on the window sill, there's a big black ring apparently from a pot that leaked and over time it left this black mark. Is there something I can use to remove it. If I have to refinish it will sanding remove it or is it probably to deep into the wood. The windows are varnished and If push comes to shove, I'll paint the windows white, which I really don't want to do unless there's no option in removing the stain and refinish the sill. Thanks for taking the time out to read my message.