Exposed metal prep advice
 

Okay guys. I had the car sand blasted a while back and due to the delay in metal repair it has developed surface rust. What is the best solution t remove it. I would rather do it myself and then seal it with something. Advice or suggestions???

D/A with 80 or blast it again. When done spray Picklex20 so you won't have to do it again

With a wheeled grinder or just by hand? Thanks

I have to agree-----that Picklex20 is pretty amazing stuff.

I use 80 da, wire wheel, course prep disc, hand sand and than apply SPI epoxy primer.

Wheeled grinder? I have no idea what that is. Use a D/A sander aka dual action sander.For tight areas you will have to do it by hand or use spot blaster.Make sure to remove any shiny glazed spots if you used wire wheel or prep disc

Okay thanks. Now I understand.

i may be missing the obvious here but could you explain what the difference is between epoxy primer and this picklex 20 stuff? is the picklex 20 better to use if the metal is going to sit around longer w/out coating vs. epoxy primer?

picklex 20 is great when you want to leave bare metal without any primers for extended periods of time,if you're doing alot of metal work and it takes months to finish, you won't have to grind or remove primer to weld, picklex also makes welds cleaner.This is not a primer.

here is a link to their site, http://www.picklex20.com/

Keep in mind that although Picklex 20 is excellent, it is not compatible with a few paint systems including House of Kolor. The primer will peel.

Just an FYI-otherwise it works great!

Wes

another question for you. so would primer go over top of the picklex once ready for that stage or does this stuff need to be removed prior to priming and painting?

thanks for the link as well, going there now. :thumbsup:

Yes, just scuff the surface with 180 or 120,no need to remove it completely, wipe with prep-solv and shoot primer

What many folks don't understand about "primer" and or "bondo" is that both are hygroscopic - in other words - they absorb moisture over time. So lots of "home" guys will do bodywork and then 'prime' the work.... and then 3 years later seal it and paint it.... or they "think" they are doing good by priming bare metal -- and it sits for a long time in humid and unheated shop... and that bare metal under the 'primer' (filler primer) can be rusting up.

Then they take it out in the sun.... and wonder what the hell happened... and blame the painter.

It really pays to explain what you're doing when talking about your project to a "pro" --- so they can guide you to the RIGHT products for YOUR application. Know ahead of time what paint you plan to use - at least as far as type and brand (i.e., base/clear or single stage or water base etc) and make that known as well. :cheers:

Greg,I agree with you for the most part, but if the metal is clean and sealed with epoxy primer, it should not rust if it was shot right away in dry and clean environment . Epoxy primer is the only primer that blocks moisture, that's why anyone with common sense will epoxy the metal and do their skim filler work over that, otherwise if filler is applied over bare steel,it will attract moisture and absorb it like sponge,

I've had to fix more than few cars that looked decent,but upon removal of filler and primer, I discovered rust, I've even had some cars with few repaints and no bodywork and yet they had rust underneath factory paint/primer, so I would never trust factory 40+ year old paint.

Stefan -

That's why when I said "primer" --- I said filler primer (or similar) not EXPOXY primer...

For the most part - the average guy thinks that it's "painted" when it's in just ordinary primer (there's many names and kinds).

No wonder I have two plastic cars!


EEEEEEEEEEEEEHHHHHHHHHHHHAAAAAAAAAAAAAAAA

Greg, we're on same page, buddy:cheers:

Can you use epoxy primer on bare metal or do you have to lay down etching primer first? Or does epoxy primer etch? I honestly have no idea. :_paranoid

Thanks

Most epoxies are DTM (direct to metal) and many of them specifically state NOT to use any form of etch primer etc under them.....ALWAYS read the spec sheet for the product you use... the sheets are availbale online as well as most of your paint supply places have them.

Great, thanks Ned. I'll look into that this week.

Heres A ? what do you guys do to promote the adheasion of the filler to the Epoxy? i know there are 2 trains of thinking one being that the filler will adhear better to bare metal than to the Epoxy, and then there is the issue of the filler attracting moisture. but if the filler is applied to bare metal and then epoxied over?? where is the moisture going to come from?
my thought would be this in the really obvious areas that need filler "sand/grind" with 40 grit" epoxy then fill then re epoxy the bare metal areas, then filler primer, and we have used the Evercoat slick sand for this, great product NO SHRINKAGE and affordable, basically spray filler, then a final primer and paint.

lets debate

Here's the problem with debates like this... IMHO.... and everyone on here knows I'm the "H" part of that...

Someone that has ALWAYS done something wrong... will debate endlessly "why" they do it wrong. In the end - what we're all looking for is the PROOF of LONG TERM results.

In that vein --- I would think that the right way to do this is to see what the actual manufacturers have to say about their product usage.


Here is the text copied directly from 3M "tech specs" for their brand AKA: BONDO

• Clean surface with warm, soapy water to remove all wax, grease and oil. Allow to dry. • Sand the damaged area with coarse 80 grit sandpaper to remove all paint, primer and rust down to bare metal. Sand 1 to 2 inches
beyond damaged area. Remove sanding dust.


EVERCOAT -- Rage Gold:


Since I can't cut and paste their FAQ on this topic I'll just tell you basically what they say.

They want their product applied to CLEAN BARE METAL -- Unless you want to apply it over epoxy primer.... Which is 'okay' IF the metal manufacture requires that.. but they'd prefer just clean bare metal.

Here's the link to their (Evercoat) website with FAQ's discussing this application:


http://www.evercoat.com/faq.aspx

If I recall correctly the DP90LF has a 7 day window where the filler will stick to it just fine....just as good as metal. If you go past that window, you need to scuff it with 80 grit before applying filler.

As for the moisture debate I think the issue with is that alot of guys will do filler to bare metal but then it will sit for quite awhile before they epoxy over it....if it was epoxied shortly after filller, it would seal the moisture out just fine....its that gap of time that is the issue

This can be debated forever.... there will always be guys that insist on doing filler to bare metal, and have been doing it for 40 years and never had a problem.....and then there will be the guys that are more flexible as technology changes and are willing to change their techniques as the products change.

My advice....follow the tech sheets....

Blake-

What filler are you using?

Do fillers differ in moisture absorption over the short term and how they react to bare metal vs epoxy applications?

we have always used Evercoat fillers, and the Slicksand spray from Evercoat is Awesome, spray it on like a filler primer, setus up fast 2-3 hours sands fast and next to ZERO shrinkage. you can leave it in the mixing cup and even after a month it is a perfect mold of the cup. unlike most filler primers that you have to add reducer to. you can coat the whole car and long board it down to 220 and then a thin coat of final prime, fian sand and paint.

as to the second ? no idea that is a ? for the chemists.