Hi All,
After watching a tv show on the bmw z4 factory I started wondering what is the proper prep of bare metal before paint (not in the factory, but by panel beaters and restorers)?

I'm really keen to do the best to avoid future rust under paint and have a long lasting paint.

Thanks,
Rob

bare metal, w&g remover, etch primer, epoxy primer, paint??

I am no expert of refinishing but one thing I know. Treat every single process like you are spacecraft engineer working in a class 100 clean room at NASA.

Don't touch any surface with your hands or any part of your body, don't even breath on it.

Cleanliness.
Right temperature.
Right humidity.
And follow instructions of the products used. (Do not use "1 glove fits all" tactic on paint/preparation products)

Thats all the advice I can think of right now.

This is how we do it at our work

- Bare metal, complete. Soda blast outer panels, garnet blast (framework, chassis and floors only), paint stripper, sander, strip disc etc. Must be clean with no rust, sealer, paint or acid residue. "Rust converters" are not used. We remove all rust completely.
- De-oxidine.A phosphoric acid detergent-type metal cleaner and surface rust remover. Removes rust and light deposits of mill oil and destroys corrosion stimulators. It will also condition for painting all iron metal surfaces.
- Two pack, Polyvinyl Bu-tyral, zinc tetroxy chromate based etching primer, designed to promote maximum adhesion.
- Two pack high build polyamide cured recoatable epoxy coating

Then any polyester filler is done on top of the epoxy.

Then a coat of epoxy to seal any filler forever from moisture.

Then the topcoat paint love starts.

general bare metal speaking.Check for rust spots,
surface rust.Hit with a bit of deoxidine,that should get rid of most of the heavy surface rust and
so forth.if ready for priming mask up,and prep.to prep,Wipe the panel all over with metho,let dry a little.
Wipe all over with prepsol,and then prepsol again.Making sure the majority of dirt and foreign matter is gone.
NOW...once you have sprayed prepsol on the panel.Do not touch with bare hands.The oil and grease will
transfer onto the panel.Making the whole process pointless.once prepped,do not touch it.spray it with
some primer,generally 4 coats,allows enough room for blocking back.Remember everyone has different techniques

Hope that helps

Good Luck

I've never heard of de-oxodine, but at tafe I remember the the teachers mentioning applying some metal prep to bare metal and then rinsing off with water. Is that the same thing?

Now it makes sense why the good quality paint jobs cost so much.

So I assume that epoxy and 2 packs are definitily a no-no for diy at home right?

De-oxidine and Metalprep are based on phosphoric acid. They do a great job of etching bare metal, and preparing it for the first [etch?] primer coat.

De-Oxidine. After conditioning, the metal must be thoroughly rinsed with water. The rinse should be overflowed continuously at a rate which will keep it clean from scum and contamination.

Read the instructions.

Great info thanks everyone!

i take my car down to bare metal, using paint stripper wet & dry paper and a wire wheel for the tough spots. Bare metal is the best base to paint on, and never sand blast. It will take your penetration coat off from the factory and can ruin the paint that goes onto your car later on. So paint stripping and sanding if the best way to go, sure it takes a S#*! load of time but the finish will be perfect. Also 2 pac prima is the way to go and POR-15