Flash rust after ospho rinse question.

[Toad455]

Hello, I have my C10 cab totally sand blasted, wiped with Ospho and it sat for a few weeks. Rolled it outside on a rotisserie and sprayed it down again and let sit for about 30 minutes to loosen up the previous ospho, then power washed with Por 15 degreaser, then water. And of course I got the "instant" flash rust. I will be using Summit Racing DTM Epoxy primer which calls for a phosphate acid wash and rinse (but not mandantory). My question is being there is absolutely no way to get to every place to sand off the flash rust can I shoot over it with the epoxy? I can get to the outside, floor, etc, but like inside rockers, firewall, behind dash, etc, it is impossible to reach. What do ya'll do regarding flash rust?

 

[Ricko1966]

I'd hose it with ospho again,hand rinse it with water and a rag and epoxy it the same day. Preferably I'd use a primer I could shoot over the ospho. I'd shoot a test panel over the ospho. Here's some screenshots from another forum. I prime right over dried ospho,but that's inside doors,trunks,wheel wells,and floor panels using enamel.

 

[Toad455]

Thanks much Ricko. I did a test three days ago, I mixed up a small bit of the epoxy and brushed it on the flash rust on a place about 10" x 10", two thick coats. I did the same on a place that I re-wet with ospho with a rag to remove the flash rust and let dry, no water rinse. After three days I sanded with 80 to bare metal, both "appeared" to be okay. Primer was dry and dusted off the sand paper, no clogging. It was strange that on the place with the flash rust that when sanded there was no apparent trace of the flash rust, it looks like nice clean metal. I may be over thinking this but I can't stand shooting over the flash but I may have to.

 

[Toad455]

Ok, I did a test last night: I saw somewhere on the internet that if you rinse with denatured alcohol it won't leave flash rust. So I bought a quart just for a test. I re wet an already osphod panel with ospho, then rinsed with distilled water and still got the immediate flash rust. So I did it again and right after rinsing with regular water I rinsed with the denatured alcohol and when it dried by itself there was no flash rust. I'll get a 5 gal bucket of the alcohol and won't have to worry about it.

 

[Doppleganger]

I had to use zinc-phosphate (metal ready) on my cab because the loony weather here - got cold/damp/winter overnite so couldn't get it into primer. Worked great over the last winter but have been told by a number of suppliers (even Eastwood) that I will have to have it blasted again to get the phosphoric acid off thoroughly enough to put epoxy primer over it. Thats the plan anyways.

 

[Toad455]

I had to use zinc-phosphate (metal ready) on my cab because the loony weather here - got cold/damp/winter overnite so couldn't get it into primer. Worked great over the last winter but have been told by a number of suppliers (even Eastwood) that I will have to have it blasted again to get the phosphoric acid off thoroughly enough to put epoxy primer over it. Thats the plan anyways.

I considered re blasting as well, I guess with your climate you don't have a choice.

 

[Doppleganger]

I considered re blasting as well, I guess with your climate you don't have a choice.

Ohio isn't a climate....its another planet with a totally different atmosphere. At times, I think it may be a whole 'nother dimension altogether. Why anyone lives here voluntarily is beyond me.

 

[Ricko1966]

I had to use zinc-phosphate (metal ready) on my cab because the loony weather here - got cold/damp/winter overnite so couldn't get it into primer. Worked great over the last winter but have been told by a number of suppliers (even Eastwood) that I will have to have it blasted again to get the phosphoric acid off thoroughly enough to put epoxy primer over it. Thats the plan anyways.

Check with SPI they'll tell you rewet it with ospho and I'm not going to try to remember and quote but check with SPI,you don't need to reblast it. I found it,posted a screen shot,looks like reblast is not the answer do to adhesion loss or I would assume so they only referred to sanding,but I imagine sandblasting is in the same category.

 

[Trucksareforwork]

You can definitely over think this.

"Flash rust" is in the eye of the beholder. For me, a very little bit of copper coloring that comes up between rinsing the panel and blowing it dry with clean, dry shop air is not going to cause a bit of an issue with an SPI epoxy coating. I would probably hit it with an 80 grit on the DA real fast just to be sure, then wipe down with W&G remover, and then shoot it. All steel probably has some oxidation on it that you can't see and that is inconsequential to the coating.

But then there are guys who will have an orange patina from leaving a panel out in the dew and still call it "flash rust." That's a no no for me. I would re-rinse with ospho and a scrub pad, then rinse the (wet) ospho with water, followed by a very quick blow dry.

 

[Doppleganger]

Check with SPI they'll tell you rewet it with ospho and I'm not going to try to remember and quote but check with SPI,you don't need to reblast it. I found it,posted a screen shot,looks like reblast is not the answer do to adhesion loss or I would assume so they only referred to sanding,but I imagine sandblasting is in the same category.

I talked with SPI, as well as a couple other different makers of epoxy primers and it always comes back to "it SHOULD be ok...." if I wet it and power wash it off. Eastwood was pretty adament to blast or use a sander (which is a PITA to get into the nooks and crannies). The only 100% guaranteed fix is to just blast it again. There were areas alot more seam sealer came out and there was a line of very light rust down in a seam, so would like that all thoroughly cleaned out too. Guy who does it for me does my powder coating. His blast-bay is the size of a semi w/trailer. Said he'd hit it again for $50. Cant beat that but still gotta waste another 7 months before this worthless zip code has human weather again.

Depending on how $$$ is come Spring, Plan B is to dip it and then e-coat it. Doesn't get more thorough than that.

 

[Toad455]

Ohio isn't a climate....its another planet with a totally different atmosphere. At times, I think it may be a whole 'nother dimension altogether. Why anyone lives here voluntarily is beyond me.

Wow, ha. I thought Texas was bad.

 

[Toad455]

Check with SPI they'll tell you rewet it with ospho and I'm not going to try to remember and quote but check with SPI,you don't need to reblast it. I found it,posted a screen shot,looks like reblast is not the answer do to adhesion loss or I would assume so they only referred to sanding,but I imagine sandblasting is in the same category.

Thanks for that info.