Originally posted by Dubz
what i did in a few spots on my car that were too small to justify cutting them out i blasted, then used phosphoric (sp?) acid to treat the rust, then hand sanded then applied chopped fiberglass over them, i'll let you know in 3-10 years how it worked out.
Just FYI, the metal ready solution for Por-15, I'm thinking is indeed Phosphoric acid. And technically, it's supposed to be flushed off of the metal. I don't know if it would cause any long term problems leaving it on, but it does leave a crusty-residue if you just splash it on and let it do its thing.
This all occured to me when I was up at Wray Schelins shop, he had me use some Naval Jelly to scrub some surface rust off of some panels he had formed. Naval Jelly is basically just phosphoric acid in a jelly form.
But rather than just rub it on with the steel wool, I had to work in small areas and use a soapy spritz to clean it off afterwards. The areas I didn't clean well enough were apparent, you could see what looked like dried toothpaste on the areas where the acid was still sitting.
ALL IN ALL,
I don't think there would be anything wrong with using the metal prep or phosphoric acid on an area and then NOT flushing it off. Especially if the area is not going to be visible.
I'm by no means any kind of expert, but I've used POR-15 on the insides of my doors when I had them cut apart. What I would do if I could do it all over is.
-Get a good supply of the metal ready crap.
-Good supply of POR-15 AND thinner.
I'd put on a respirator and load up a paint gun with the metal ready and spray the inside of the door down quite well. Then I'd load up the gun with the POR-15 with thinner and spray the inside, trying to saturate it.