We have had 4 oak doors hung recently.They can be waxed or oiled. My husband gently rubbed down the first one with fine grain wire wool and then hoovered up the dust and the door and wiped it over with a damp clean cloth.tThe following morning the door was covered in a fine black residue.We have tried to use the wire wool again and the door is better but still not as it was.Any advice please as i do not want to start applying wax with some dark areas still on the door