Need Bodypanel rust/primer advice

[monty23psk]

Hey everyone, I am not a body guy but love to work on this. I decide to learn and treat some surface rust on my trunk lid. I know I need to paint the car but due to family responsibilities, I can't have this done now. But I want to nip the rusting and dont care if I have gray primer patch as I already have some metal exposed areas on the car. WHat are my best options. I basically used a wire wheel and some CLR/scuff pad to get it to this point. From readying may many body forums or even youtube videso, I get mixed opinions. So I believe I have two options, primer it with some epoxy primer then fill in with body filler to fill in the larger pits and then sand. or fill in with filler, sand, and then primer.

The area has some small pitting which is my needing filler or something. I believe I got all the rust out and I believe I can use the vinegar/water mix to make sure or get some rust prevention chemical.

Please let me know what you propose and why. Half the surface area was under my rear spoiler which is removed in the last picture.

[deansweet]

just por-15 it until you are set to re-sand, fill and repaint.

It comes in red, may not match but better than rust.

[DesktopDave]

I use a similar technique to yours. After the abrasives, I tend to use some spray-on phosphoric acid rust converters first. It's quicker than vinegar, although pricier. Then a little primer or POR15, then a few light coats of red enamel (Rustoleum Sunset Red?). It's not a perfect match but it's pretty close. I'd personally avoid epoxy primers...they're expensive, poisonous and difficult for DIY'ers like us.

I've never had 100% success with any technique though - really heavy rust will return in a few years. POR-15 is expensive and not a lot of fun to use. Be sure to put a layer of plastic "Saran" wrap over the can before you tap the lid back on, otherwise you'll never ever ever open that can again. It's not UV-stable either (like most primers), so be sure to top-coat it.

As for items smaller than a trunk lid, I use vinegar, or a chelating agent like Evapo-Rust, or a reverse electrolysis bath. All work well, none are perfect. I've heard that a long warm bath in feed-grade molasses works well too...and it's cheap!

[monty23psk]

Thanks guys. Here is my plan after a week of reading bmw forums, autobody forums and watching youtube videos with good trusted sources like Kevin Tetz for example.

Because I want to paint the car and dont have time, I will do the following to extend the life of the body panels. I have uses POR-15 and it isn't fun. Also for outside exposed panels I would tend to stay away due to the thickness and UV incompatibilities.

I have cleaned the area, have some etch rust remover on order. Then I will epoxy the area, a 2k product in a spray can. Then instead of filling and then adding another surface primer, which then I should paint but not wanting to do that now, I will just paint over the primer with factory color match spray paint from paintscratch.com. I will then clear it and then buff the whole trunk. Everything via spray can for now. My air compressor is not really strong enough and don't need another expense either.  I can take this approach for other areas of the car for now. The car is currently a 20 footer with low light, lol, so this will not degrade and maybe enhance the appearance after I buff it.

I wanted the bright read factory color so I can paint my primered iS lip, maybe mtech1 rear spoiler and maybe the iS side skirts I have. I still need to install them, which I would like to do before the full car paint job.

when I am ready to do the whole car, I can then sand/prep/fill as needed. At least the epoxy can work better than other products in keeping moisture out and preventing rust. The panel is very intact minus the pits.

I will of course journal it on my thread.