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PSA: Stop sanding body filler with 80 grit if you want it to last
I keep seeing jobs come into the shop where guys are knocking down filler with 80 grit then shooting primer right over it. Those deep scratches come right back through the paint after a few months in the sun. I had a customer last summer with a 2018 Ford F-150 hood I redid because of this. Use 180 at minimum for the final pass. Takes an extra 10 minutes but saves a comeback. Anybody else dealing with this?
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the_sandra24d agoMost Upvoted
Wait, you're saying 180 is actually better? I always used 80 but now I'm rethinking.
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the_tara18d ago
Did you ever read that article from the old hot rod magazine about how sanding scratches act like little stress risers in the paint? I remember it talking about how each deep scratch is basically a little crack waiting to split open when the sun heats up and cools down the panel. That 80 grit leaves furrows that are just too deep for primer to fill, even if you lay it on thick. I've seen it happen on a buddy's old Chevelle - looked perfect for about six months then those lines showed up clear as day through the color coat. 180 is safe, but I've actually been going to 220 on final passes for the last couple years and it's made a big difference. You don't lose any adhesion if you scuff it good before the next coat anyway.
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