Waterborne WG remover before epoxy question

R

robking

Promoted Users
I'm getting ready to epoxy the first panel on the car that is DA sanded. Pretty much everything I've epoxied up till now has been blasted. I *thought* I had the panel ready to go this evening, and began the wipe down process with SPI waterborne WG. I have a couple of sections that I struggled to get to wipe clean, and thought I'd better ask if I need to back up and do something different.

Here's an example. I've wiped this section of the panel down repeatedly by spraying then wiping with Finish Master wipe down towels.

PXL_20230802_000034159.jpg


After several passes, I'm still getting what I'm starting to think is rust maybe?

I didn't want to epoxy until I understand what's going on.

The quarter was washed with dawn, then stripped with a 3M clean strip on a 4" angle grinder before 80 grit DA.

Thanks for any and all advice.

PXL_20230802_000230466.jpg
 
Under certain conditions, I suppose it might be possible for the water in #700 to cause flash rust, though in my conditions I have never seen it. It would be good to hear from others on this, but that's what the residue looks like to me.
 
BTW, if it IS flash rust, it just means you have such a clean panel the atmospheric oxygen and moisture are getting friendly with the iron atoms in the steel. That's not really a bad thing, if so. Just prime it asap.
 
Light rust is what it looks like. Usually a quick fresh 80# DA is all that is necessary. I have also rewet the 700 giving it a maroon scotch brite, wipe it, then one more wipe down process. Metal sure looks pretty after that.
 
crashtech said:
I guess I might have asked how long it's been in bare metal. I am really strict about that, it's either same day or next morning if at all possible, we don't mess around with our foundations.
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Thanks folks. It's probably been a couple days with high humidity, I think I will DA the whole thing tomorrow and try again.

Is there any value in washing again with dawn before hand?
 
Not in my opinion, unless you have a dirty air supply that's sputtering water and oil all over while you're sanding. Even then it's a toss up because the #700 does an amazing job. We do not water wash bare metal since using SPI.
 
texasking said:
Light rust is what it looks like. Usually a quick fresh 80# DA is all that is necessary. I have also rewet the 700 giving it a maroon scotch brite, wipe it, then one more wipe down process. Metal sure looks pretty after that.
Click to expand...
i was going to add that i also scrub bare metal with 700 and red pad before using wipes. but i didnt know if it was the right way. thanks tk!
 
remember that the flash rust your seeing is not really a problem. its not the type of rust you need to worry about. that panel could be completely flash rusted in a light orange haze and you can epoxy over and it will be fine. the rust you need to worry about are the black stuff down in pits, etc. the spi epoxy will kill any flash rust. here in nj in the summer the humidity is 95-100% all the time. you can blast a surface and it will flash rust faster than you can blast. never an issue
 
Thanks for all the help folks. I hit it again with DA, wiped again and I still got faint rust but not very much. I let it sit for an hour and shot two coats. Going to start slathering on the rage ultra this weekend.
 
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