How to Fix Rust Pits In Body Work
If you are lucky, your project car is straight with no big holes rusted in in behind the wheels in the fenders and quarter panels. But even if there is no rust through there, you may find that rock nicks and chips have allowed salt and moisture to eat little pits in the metal.
These pits aren’t deep, so they are easily filled in with Contour body filler, but doing that without first addressing the rust will cause you headaches down the road as the rust continues to eat into the metal.
In order to properly treat, fill and prep the fender, just follow these easy steps:
Apply Eastwood Fast Etch to the area with the rust pits. Cover the area with plastic wrap to prevent the Fast Etch from evaporating before it can work. Fast Etch eats into the rust, dissolving it and leaving clean metal behind.
Next spray the area with a coat of Eastwood Rust Encapsulator, which penetrates deeply into the pits and adheres to the metal, keeping the rust from coming back or spreading by absorbing moisture.
Sand the panel and remove all the Rust Encapsulator except the stuff that soaked into the pits, leaving you with mostly bare metal.
The Rust Encapsulator in the pits will keep any microscopic rust from growing, allowing you to safely apply body filler over it. Body filler alone won’t seal out moisture the way a dedicated product like Rust Encapsulator does because it is porous.
Now proceed with your normal body work as if the rust was never there. Scuff the entire area with a dual action sander for adhesion.
Blow off the dust with an air gun, then wipe clean with PRE paining prep.
Mix up your body filler and spread thinly and evenly over the entire surface, most of it will end up as dust on the floor eventually.
Sand first in one direction, than in another, producing an X pattern of sanding passes. You can start with as coarse as 80 grit, if you have a lot of filler to sand, but 180 grit is likely plenty. Use a sanding block and you will quickly reveal any high or low spots in the body work.
Low spots will be revealed because the sandpaper will pass right over the filler there and not leave any marks. Take a small piece of paper and scuff any low spots you find so another round of body filler will stick to it.
Apply another round of body filler, though more localized to where the low spot is, and sand it smooth again. Repeat as necessary until you can’t find any more low spots.
Blow out the dust with an air gun, and if you find any pinholes fill those with Contour Glazing Putty.
Now that the rust pits and low spots are taken care of you can move onto the next phase of your project. That could be primer and paint, or if you’re going for laser straight body panels spraying and blocking the whole body of the car with Contour Polyester Primer Surfacer.