Another “How to deal with flash rust” question
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I’m having a heck of time with flash rust on the latest project. I live in North Carolina, and it’s really humid out right now, and I can’t seem to get this car ready to go into primer to save my life. I stripped the entire car with Aircraft paint remover, and the exposed metal was rusted almost immediately. I ran over that rust with some 180 grit on a DA and it comes right off, but I am concerned about getting the rust all off the car before I put an epoxy primer on it.
I am doing research, but haven’t found anything that outlines a good process for dealing with this issue. I’ve read about phosphoric acid, and think that might be the best solution for me; but I’d really like to discuss it with some knowledgeable folks before taking the next step.
Buzzing the surface rust off the car with the DA leaves a rust powder all over the car. I’m concerned about that rusty powder not being completely removed from the car when I cover the car with Epoxy. The last thing I want is rust coming back in short order on this car, and I feel like a few pieces of rust dust buried beneath the epoxy and up against bare metal might cause that.
Even if I work one panel at a time, then epoxy primer one panel at a time, what’s the best way to ensure the surface rust is in fact completely gone before priming? Is it something you can see with your eye, or does complete rust removal require dipping of some kind?
Am I over thinking this? Can I just knock the flash rust off the car, wipe the car down with wax and grease remover really well, put the car in epoxy primer, and expect it to last 10 years or more?
Thanks in advance, any and all advice is appreciated.
Did you neutralize the chemical stripper immediately after using it?
Typically chemical stripping is used for single panels/smaller jobs, not entire cars. If there is any existing corrosion, media blasting or other means are necessary.Nonetheless, after chemical stripping, then neutralizing it, the panel should be dried well immediately. Within a day or two the bare metal should be sanded (usually with 180 on An random orbital sander). Then cleaned and primed immediately.
If the corrosion (flash rust) is minimal, a good sanding or light grinding should be good. If its gotten bad, then media blasting is they way to go. You can apply acid and such, but that is not a sure fire way to cure existing rust. In any case, prime the thing as soon as possible…epoxy or etch.
if its true flash rust your talking about, the stuff that forms when its humid in a mater of a few hours then as long as your using a good quality epoxy it will instantly choke that off. flash rust is usually faint and a bright orange and when you wipe your hand over the panel it will come off on your fingers. basically dont worry about it. if its pits in the metal or rust that has been there a while then thats a different story. stay away from the acid treatments. they usually leave a film behind that acts more like a coat of wax and your primer will only be bonded to the film. primer will usually flake right off of it. only product i have found that works really well is the metal treatment wipes from sikkens. henkle actuall makes them. they work fantastic though and dont screw with the adhesion of your primer.
Yes, it’s the rust that forms in just a few hours (or minutes it seems like).
The chemical stripper was on the car for roughly 30 minutes before being hit with water, so it wasn’t neutralized immediately.
I’m going to prime it panel by panel removing the rust as I go. The rust comes back so fast that I can’t make a complete lap around the car removing it – by the time I get back around to where I started, the rust has started to regrow.
Blasting the car would be great, but I don’t have the equipment to do it. If that’s the only way to get where I want to go, I’ll go ahead and make the investment, but I’d like to avoid that if possible.
Thanks for the advice, I’ll steer clear of the acid and other rust converters / preventives.
I managed to get the deck lid for the trunk into Epoxy today. I ran over it with 120 to knock off several days of the flash rusting, washed it with dish soap and water, dried it, air dried it, mixed the DP90LF with 401, while it induced for 30 minutes I wiped the panel with the sikkens prep wipes recommended here. In just that 1/2 an hour, the panel was already starting to turn orange again. I wiped it one last time with a dry paper towel and put the Epoxy on it.
Hoping to repeat that process on the entire car tomorrow.
Thoughts or criticisms of my process?
I do pretty much samething in my shop but I don’t have that big of a issue with flash rust. We clean it and dry it and try not to touch it with bare hands. Sometimes threw some sanding dust on it.
Like said before the minor flash rust won’t hurt to much I usually get everything ready and run over the metal really quick with 80 before priming to get the rust offAbout phosphoric acid metal prepping rust have a look here:
http://www.youtube.com/watch?v=JML4q2Dfe9g
This guy does high quality restaurations and explains things very nicely.
I hope this helps.
All of the horizontal panels are in epoxy (thank God).
However, the roof and hood have some pitting that has rust in the bottom of the craters. After talking with the customer, media blasting isn’t really an option, so per that video we are going to try some rust mort from SEM.
well of all the stuff that guy said the most important thing is that he wipes it down with water, a scotchbrite or resands it when he is all done. if you leave any acid or the zinc film behind your primer is going to peel in sheets. seen it time and time again. you really need to watch yourself with that. problem is when you wash the fim off with water and a scotchbrite your just going to flash rust again…….real bad so imo what is the point. your better off sanding a panel and epoxy then sand another and epoxy and so on.
on another note, what the hell kind of resto shop doesnt have 80 grit!!
Who doesn´t have 80 grid?
oh , i see , but this is not his shop , this is taped in his home garage , he actualy works for Photofinish from Tucson and has about 150 vids on youtube ( http://www.youtube.com/channel/UCqCRBowSBc3OVvptRY10ZJw )
Hi guys n gals. I wanted to weigh in on this flash rust topic. Perhaps a person should veiw the problem from a point of prevention rather than cure.
Living in Iowa it does get VERY humid here . We have on occation have had this issue as well . We then turn to our old friend….the dehumidifier…sometimes we use more than 1. Buy em cheap at auctions and garage sales , estate sales etc etc.
A person could also “RIG” up some type of hanging plastic barrier and segregate the car into its own room and dehumidify that space. Hope this helps someone.
Cya.
Ken from Coachworks.
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