Iron in any form, whether Cast or Malleable, is susceptible to rusting. This is true of all iron hardware Whitechapel supplies and in some cases is viewed as a feature instead of a flaw. To remove slight rust deposits which will cause corrosion (this is even more critical where on lives near to a coastline, as the salt in the sea air has a very corrosive affect on iron) we advise that iron hardware is regularly wiped over with a oiled cloth and followed by a light coating of a wax based furniture paste.
We strongly advise that these precautions are taken if the original finish is to be maintained. If a heavy build up of rust allowed it is unlikely that the original finish will be regained. It is possible remove some the rust with very fine steel wool or fiber tex pad and a light machine oil (3-1). This should be done with care and patience as it is possible to remove rust as well the original finish and end up with raw iron.
A coat of furniture paste as mentioned above will finish the job but the end result will most likey be a dark reddish brown instead of black.