How do I get black stains off an oak worktop?
Those stains happen when the iron that’s in water interacts with the tannic acid in the wood. Sometimes the stain can be removed with a product containing oxalic acid — that’s what wood bleach is, and you can get it at a hardware store. As for household products, I know of two that contain oxalic acid. There’s Zud cleanser, and Whink rust stain remover. Sanding will also remove black marks on wood, if they’re superficial.
