Proper paint prep

[Adam]

I’m currently removing rubberized paint from the roof of my car. Previous owner painted the hood and roof likely because the clear coat started coming off. Im guessing the rubber paint was at least 5 years old. It’s flaking on the hood and rust is popping through on the roof.

Is my best course of action to sand down to bare metal and then prime?

From the Picts I took it looks like theres a film of rust under the original primer. I’m going for effective, durable and cheap. Looks aren’t my concern. I plan on doing rustoleum flat black over the primer.

Thanks

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Topic

[jonathan]

I usually do this, sand the panel, the more you sand the better it is, getting back to metal is the preferred method, grind the rusty areas and maybe use fiberfiller on the uneven rusty areas to prevent water from getting in, wax and grease remover before priming, prime with 3 coats, wet sand with 600 grit, wax and grease remover again, and spray 3 coats of Rust-Oleum in your case

[Fernando cunha]

best way scuff old paint with 30P sand paper ,next buy some plastic drop sheets and masking tape,paint stripper,etch primer,high build primer,paint etc
mask panels you don’t won’t to repair.
poor stripper on damage paint spread it with brush it will take 15min to 30min
for paint to start pealing off use scraper to remove paint, continue to poor stripper until all paint is off .
get some paint thinners or wax & grease remover clean bear metal by wipe on wipe off with 2 rags.
apply 1 coat of etch primer wait 5 min apply 2 coats hb primer.
depending on the type and brand of paint normally 20min wait them apply top coat color wet on wet.
good luck

[Fernando cunha]

also for small surface rust you can just use 40p sand paper on sanding machine or just wire brush on a drill it will clean the bare metal ,if you use grinder you will put deep scratch marks on metal surface and you will need to use more primer to fill as well as rub down primer ,other words giving your self unnecessary work

[dropin_biking]

What kind of primer did you plan on using? Unless it’s a 2 part epoxy or a quality etch or sealer, you will be right back where you started. Generally anytime you have a compromised finish you want to sand all the way through it. If it’s rusting under what’s on it, get it sanded back to bare metal. 80g on a 6″ palm sander would do nice work without chewing into the metal. That rubberized paint can be a pain to get off, and it likes to gum up the sand paper. Maybe try some aircraft paint stripper? That might speed up the process.

Generally if you don’t want to get into putty or high build primer, you want to stick to 80 grit + I usually strip panels with 120 on an 8″ rotary (being careful not to dig in with the edges) Followed up with 80g on a 6″ dual action, than 180 on a 6″ dual action.

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