I have some ledge and brace doors that have previously been stained and then rehung. So where the locks and hinges were previously fitted is much lighter with some dribbles where the old stain ran behind the fittings. Is it possible to lighten the doors to a uniform (unstained)colour prior to waxing them? The stain is a matt type that has soaked into the wood. I have read that oxalic acid only works on bare wood. Thanks, Paul.