I have a couple of really great porcelain signs that are in really nice condition on the front side. But the back, has pitting and rust from being hung outside during their active service period. I was thinking of brushing on some Por 15 or other rust nutralizer to stop the rust process from bleeding through and potentially damaging the front of the signs. I think this would be a better option than waxing but it is permanent. what do you guys think? any other suggestions?