Jasonmreiss Posted February 13, 2012 Share Posted February 13, 2012 Ok I'm confused by all the product fluff and all the different opinions of pro painters. I'm really trying to learn and search and read, and read, and read. So I read and now I'm ready for more confusing opinions lol. I can't afford a complete sandblasting or dipping service at this point, but my plan as of now is to por15 the interior and engine bay, and ospho the exterior panels. Prior to etching, epoxy primer, build primer. Will this idea keep the masses happy? I just need to take care or surface rust and be able to paint over it. There's so many differing opinions I'd just like to know if I'm fn it up 1 Quote Link to comment Share on other sites More sharing options...
morbias Posted February 13, 2012 Share Posted February 13, 2012 (edited) POR 15 and Ospho are two different things. POR 15 is a rust encapsulating isocyanate paint, Ospho is a rustkiller using Phosphoric acid as a base. There is also Metal Ready (or whatever it's called now) in the POR range which is basically phosphoric acid in a spray bottle. Both Ospho and Metal Ready will kill rust and etch any metal they touch, you should use one of these before painting as the metal will have a protective coating on it as well as making the primer stick better. Metal Ready is meant to be washed off with water and then immediately dried, Ospho isn't -- though I would do it anyway as you end up with a bit of a powdery surface otherwise. If you use POR 15 then make sure you dust coat it with primer after it's flashed but before it cures. Edited February 13, 2012 by morbias Quote Link to comment Share on other sites More sharing options...
Jasonmreiss Posted February 13, 2012 Author Share Posted February 13, 2012 Perfect thanks Quote Link to comment Share on other sites More sharing options...
The Infidel Posted April 17, 2012 Share Posted April 17, 2012 Straight ospho will also etch glass so be careful. Quote Link to comment Share on other sites More sharing options...
magnum44 Posted December 7, 2013 Share Posted December 7, 2013 I used por 15 and was very happy with the outcome... Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted January 5, 2014 Share Posted January 5, 2014 (edited) That's quite a thread necro. To add info, por15 is not really for painting over and it's not really for clean bare metal. Por works best on rusty metal for quick and dirty ways to essentially drop the hammer on rust issues. It builds on it, seals it and converts it. Ospho, metal clean, etc are all just essentially phosphoric acid. Phosphoric acid gets busy with iron oxide (rust) and turns it into iron phosphate which is a stabilized (etched) metal that is ready for primer or sealer. Primer is a thinner version of sealer intended to just help with adhesion and let you paint over it with basecoat, etc. Sealer, conversely, is just a thicker primer intended to help build up thickness so you can fill in nasty scratches and dips/dents from your imperfect bondo job. You usually wetsand sealer to smoothe it out and you just scuff primer to go to the next step. Some paint lines sold today have the same exact product with different thinning and activating rates depending on whether you want primer or sealer, in other words. Bottom line: POR15, Rust Bullet and its ilk are HARD coatings intended for less appearance and more utilitarian solutions. Interior under carpet or bare on a race car, engine bays, underside, inner fenders, etc. Phosphoric acid is merely a first step towards a basecoat/clear coat process (ie., provide adhesion) and has zero long term capability by itself. Actually rust CAN show through phosphoric acid in 12 hours and through primer/sealer in a week (although sealer sometimes has more hardener in it and will hang on a bit longer). They are just links in the chain. Edited January 5, 2014 by WizardBlack Quote Link to comment Share on other sites More sharing options...
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