PSA: Stop using body filler over bare aluminum without etching first

Last Tuesday I had a 2018 F-150 in my shop in Phoenix where the previous guy just laid bondo right on the aluminum tailgate. Three months later it was peeling off in sheets. I had to strip it all down, apply the proper etch primer, and start over. Customer almost sued the other shop for the redo cost of $1,200. Has anyone else dealt with this kind of aluminum nightmare?

2 comments

2 Comments

patel.daniel1mo ago

Did you scuff it with 36 grit or something finer?

grant.margaret1mo ago

My 1998 Dodge Dakota has been held together with plain old Bondo over bare aluminum for going on seven years now with zero issues. I live in Tucson where the heat is just as bad as Phoenix and it hasn't lifted or cracked one bit. The key is to rough up the surface real good with 36 grit and make sure the metal is completely dry before you mix the filler. I think a lot of these problems come from people not taking the time to prep the metal right, not from needing some fancy etch primer. The big body filler companies have been selling their product for decades without that extra step and it works fine for most of us. Maybe that other shop in your story just had bad luck or didn't do the basic sanding properly.