Ross,
Yes you can apply it even now. There is a good chance that the many of the metal and sand particles are embedded in the remaining rust itself. After treatment w/ the fluid, I would recommend using a stiff plastic bristle brush to get any residue and metal/sand debris out of the pitting while rinsing the part in water. For heavy residue left by the removal process, there is a metal cleaner available. Once it is dry, prime, skimcoat and topcoat. Obviously, all three coatings should match chemically. Instead of adding pics here, you can see the results under examples on the website below. I would also like to direct your attention to the previously mentioned link for further discussion/questions, so the rules of the forum are not violated.
I hope this is helpful to you.
Regards, Lee
