My brother has a project where a client had some bay windows and skylights that were never finished. Problem is now they are stained from water. He asked me if Oxalic Acid would remove the stains. I told him that I thought it would, but I wondered if it would not whiten the wood so much that he would have to apply some stain so that the wood would resemble it's natural state. His clients are wanting a natural look with a clear finish. He does not know what type of wood it is.
Will Oxalic Acid work for removing the stains and can he finish with clear finish right after or should he count on some stain to duplicate the wood tone before finishing?