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Filiform Corrosion

Hornet2008

Well Known Member
Hi all. Noticed some very small patches of filiform blisters working under the paint. AC 43-13 suggests bead blasting but I think that may be a bit harsh. A mate suggested a small hand blaster like a HF cheapie and use baking soda as the blasting medium. Would use a mask to limit the area blasted. After blasting, alodine, a primer and touch up with an air brush. Anyone else tried this method of removing filiform corrosion? My top coat is PPG two pack.
 
Glass beads would be fine, but do your initial removal to reveal the base material first. Then keep the pressure below 40 psi (or so) so the blasting does not pucker the area. There are small airbrush style blasters but what ever is cheapest, the whole process will take 10 seconds. Even an auto body spatter gun would work for that long.

I am not sure why simple Scotchbrite followed by etching and Alodine would not suffice, though.

I would definitely use a chromate primer this time and it won't be back.
 
Before you start blasting away, find a discrete area out of sight and Scotchbrite a small area thru the top coat. You may find the primer underneath to be free of any defect.
I have this in a few spots on my machine. When I tested one small spot under the elevator, the primer was completely clear of any corrosion. I went further and the base metal was also clear. What appeared to be filiform was some kind of odd condition between the primer and topcoat layers. I left this spot to observe.
Years later, nothing, skin looks great and that spot has no corrosion, even left bare (it was alodined when painted).
 
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