what's the best primer/paint to use for mid project protection of bare metal

Looking for some advice, as I get going on my project, there hopefully will be times that I get some metal pieces sanded, blasted, bent, shaped, etc that will be done way before the project goes for a complete paint job.. so what is a good quality primer out there to use to protect the bare metal that won't affect the final painting process of the whole project?
Any help or advice would be greatly appreciated..

 

You will need either self etching primer or pickle it ( muratic acid diuluted is what I use) and then regular primer of your choosing. If I was just going to sand it off and paint it later I may just use a cheap primer just to protect it.

 

A primer-SEALER. Primer is open, and porous, and thus absorbs atmospheric moisture. Using primer alone may be a false sense of security, if just a bit better than nothing.

 

Epoxy primer, anything else will be porous

 

thanks for the great advice! overall, it needs to be a non-porous primer, sealer, epoxy, okay then...

 

When you say, "pickle it" with an acid (assuming Ospho falls in this category), is that ever removed when the painting procedure begins?

 

I always use DuPont Veri Prime first. It is a self etching primer. I then follow up with a DuPont primer surfacer

 

I use PPG DP90LF. It's an excellent product.

They have a fleet version that is cheaper and works pretty good. It's Comercial Performance Coating EPX series epoxy primers. Comes in 3 colors. I've primarily used the black which is EPX908. Mixes 1:1 with the EPX901 catalyst. It's a very good product as well.


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Self etch then a sealer. You'll have to scuff the sealer as per instructions before coating it again once you start work.

 

How long is it going to sit? Inside or outside? I've had good luck with the dollar spray primer from Home Depot. Stuff in my garage rusts pretty fast because I'm so close to the beach. The cheap primer keeps the rust off for six months or so if I keep it out of direct weather.

I sand it all off when I'm ready to coat with real primer/paint, though.

 

What he said^ if you are still going to be doing much of anything in the way of metalwork and welding. Something that will give some protection but be easy to get back to bare metal when you need to. I use a dusting of single-pack etch primer that I can wash off with thinners before real paint.
Save the high quality stuff for when the heavy work is all done, removing epoxy can be a bitch, and it doesn't like you welding close to it...

 

Gibbs Product is the way to go untill youi are ready for paint.
Then you just paint straight over it.
No need to remove it.

 

We use epoxy primer on bare metal, no etch primer needed and it keeps moisture out. When you are ready to do your filler work scuff and apply filler over the epoxy.

 

exactly, all the other stuff will let moisture in.

 

PPG-DX1791 good article in August '13 street rodder.

 

Just started trying that stuff out. I think I'll use it as you mentioned. Works well so far......


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SEM makes a primer/sealer it can be used both ways pending on how it's mixed. (It's self-etch and or high build)

 

Best way to do it.

We put a '54 Cadillac in PPG's DP50LF (Gray) epoxy and drove it for four years, in all kinds of weather, including snow...never rusted. Epoxy is waterproof, primer is not. When we finally did the finish bodywork, we simply scuffed the epoxy, did the bondo work directly over the top of the epoxy, sealed it again when we were done, THEN primered it and blocked. Painted it and have been driving it for five years now...still no rust.

Of course, we live in an area that has virtually no humidity...things just don't rust here from sitting around.

R-

 

^^^X2 StudeDude

I use SPI the same way... They recently posted a saltwater exposure test result showing that 3 coats instead of 2 made all kinds of difference as far as protection goes. I assume any brand will reflect that improvement if your considering leaving a frame or something like that exposed.

 

Sorry guys, there are NO water/moisture proof epoxy primers in any automotive product lines. Only some industrial coatings can claim that, and even those aren't forever.

overspray

 

Take a look at picklex 20. I hear it works great, you can leave it bare metal if inside. It also is reported to help improve weld adheasion. Body guys use it. I have not tried it yet, but I am about ready to order some. It is a rust converter as well. Can be scuffed and painted over.
http://picklex20.com/

 

I use Lechlar epoxy, it's an industrial coating and moisture resistant.

 

When I'm welding or breaking thru to bare metal,small spots get Dupli-color self-etching primer (Sherwin Williams) spray bomb,bigger areas where I'll be mixing up a 1/4 cup or more,DUPONT DTM (direct to metal) it's available in Black, looks like OEM semi flat,& White tintable ,you won't have to sand either of these products back off,too put your finnish coat overtop,yes the DTM is $$$ about $400 per gal. I'ts thick high build easy to spray dries ready to sand in2+- Hrs. I can sand blast & spray at the end of day & not have failure from the morning dew,humidity always a problem in Md.DTM is epoxy & replaces vari-prime from 20 years ago,Oh yea a gallon will cover a24' box truck all around inside & out....always use top quality paint, Good Luck

 

Any time you use an acidic product you run the risk of compatibility issues with your primers that may result in delamination/lifting. Before jumping in with both feet, check any "prospective" components for inter-product compatibility. An acid fixing the rust but reacting with primer shortly thereafter risks a total rework.


From the Picklex20 technical data sheet:

Where it's been suggested to just scuff and paint this product, the manufacturer specifically states not to use self-etching primer. Additionally, a few manufacturer's of epoxy primer state their product is not compatible with these rust conversion coatings (Ospho, picklex, Phosphoric acid, etc.)


Most people recommending rust conversion products have either done their homework, been real lucky, or haven't applied paint yet. And yet the recommendations for these conversions thus far comes without knowing what paint products you plan on using.........can you tell which group of the three they are not from?

 

PPG DP Epoxy. When you are ready for body work scuff and apply the mud or thin the DP shoot a coat and then you can use a fill primer within 7 days without sanding, it is a chemical bond. If you have any ??? contact your PPG dealer for spec sheets.

 

I store things that I don't want to rust. With a coat of phosphoric etch and prep. I get it at Home Depot. When you are ready to work with it just wash it off. I don't prime any of it.

 

Paint over lubricant? Sounds magic. I will have to try it.

 

Lechler epoxy looks to be comparable or similar in components and film build to some automotive refinish epoxy primers here in the USA, --HOK--Sherwin Williams--SPI--according to the tech sheet. The tech sheet I read did not show prep requirements for rusty metal, only new steel, aluminum and fiberglass.

Most primers and paints are moisture resistant. If you buy a bullet-proof vest, do you want bullet proof--or--bullet resistant.

Refinish systems protect by steps and layers to form a complete protective coating, from the metal-let's say steel-to the phosphate coating, which is the first step to prevent steel from corrosion, to the primer or primers used to protect the phosphated steel and help tie the topcoat or paint to form the complete protective coating. These steps of materials have to contain components/ingredients and be applied in a thick enough film to resist moisture and UV radiation, as well as chemical contaminants from breaking through the coating and corroding the metal surface.

This is why, as mentioned, you should find a system of techniques and products, developed by the manufacturer to replace an automotive paint coating.

 

can't beat epoxy,,,,,,,dries very hard......then you can sand when you're ready to paint,,,,uro 2k primer, seal then spray...
veri prime,,,or other self etching primers are a great alternative , but i typically use them only when there is a question with adhesion, or rust has been a severe issue. as well as any zinc chromate primers......
you can use either. but epoxy is a little easier, and cheaper.