Ross,
Take a look here for a possible solution to the rust in the pitting.
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=forum;f=31
Look under "RUST REMOVER"
Since rust is hygroscopic, meaning that it attracts moisture, it is almost impossible to top coat it w/o having it progress underneath.
When you use a wire wheel, tiny bits of dissimilar steel break off of each wire bristle and tend to embed in the pitting, further aggravating the problem of topcoat adhesion, not to mention that good metal is being sacrificed. The same thing happens w/ sandblasting, only w/ bits of sand.
A rust removal fluid will allow you to remove the rust completely from the pitting and leave nothing. If there is enough metal w/ no pinholes, then the surface can be primed and skim coated. This method should last the longest since there is no rust to draw moisture and no dissimilar metal, or sand pushed into the pits.
Regards, Lee
