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Raw fenders what to prime it with?

davek

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Got the fenders sand blasted and need to do metal work. So I need to prime them before they start to rust. What can I use that I can end up putting epoxy on them when I go to paint it. This will be my first car I have ever painted. Can I just use a rattle can from Napa?
 
how about this?
KEM Bond primer


A single-component, fast-drying, rust-inhibitive, universal phenolic alkyd metal primer. A high-solids, low-VOC, heavy metal-free primer, Kem Bond HS can be top coated with alkyd, acrylic and high-performance coatings.
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Epoxy first. You can do your body work on top of the epoxy if done within the recoat window. SPI is 7 days. If longer, scuff add another coat then do your body work the next day. After seal the work with another coat of epoxy. You will basically sandwich the bodywork in. Then high build and block.
 
Don't even mess with the rattle can stuff. Get them coated with epoxy right away.
 
Im not set up to do the epoxy,no gun or compressor yet. Do I need a high cfm to spray epoxy? Can I use a small compressor for that?
 
You could use Ospho (phosphoric acid) on them. That should preserve them for a while. Just make sure you ospho them again and wash it off good before it goes to epoxy. The epoxy will lift off if you don't. They also sell epoxy in rattle cans but it's spendy.
 
HVLP gun like the Harbor Freight purple, and a small compressor will work for fenders, 20 gal tank would help. Definitely get some disposable inline filters and a regulator to attach to the gun.
 
Quite a few rattle cans are still enamel based, and you do not want that, because you will have all kinds of problems putting another product over it. Do what the previous posters said to do. If no compressor, go to your local rent it shop, they normally have them for rent. Go to Harbor freight and buy a cheaper spray gun, one you can spray DTM through. It would be the least expensive way.
 
If you were closer I would mix up some epoxy and coat them for you.
 
if you must.....go to napa..... get a can of etch primer and put 2 very light coats on them, like a film.......... scratch it up/off later with 120 grit or so, and epoxy it

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if you must.....go to napa..... get a can of etch primer and put 2 very light coats on them, like a film.......... scratch it up/off later with 120 grit or so, and epoxy it

View attachment 1437396
I have always been told that etch and epoxy primer cannot touch each other. Maybe that doesn't apply to rattle can etch? My thinking is by the time he goes through the hassle of removing all the etch, do it right the first time with epoxy.
 
Im not set up to do the epoxy,no gun or compressor yet. Do I need a high cfm to spray epoxy? Can I use a small compressor for that?
Since you are taking on a major project, I assume this is your Charger, there are going to be a lot of parts you will want to epoxy prime. I'm sure you want to do as much yourself as possible. Even if you would never attempt to spray the exterior of a car, like me, there are piles of things you can do. Like all the suspension, brackets, misc. Buy a Harbor Freight blast cabinet and paint gun. Get a halfway decent air compressor that will run those 2 things and go at it. You will be ahead in the end moneywise. SPI epoxy is a great primer that is easy to spray, and they make paint as well. It will hold up far better than any rattle can.
 
I’d take them to a body shop and see if they would epoxy them. If they’re blasted there’s virtually no prep work. An hour or 2 of labor and some material.
Or the 2k aerosol epoxy cans.

If I wasn’t set-up to do it
 
I have always been told that etch and epoxy primer cannot touch each other. Maybe that doesn't apply to rattle can etch? My thinking is by the time he goes through the hassle of removing all the etch, do it right the first time with epoxy.

I stand corrected..... as per the SPI tech sheet

I always assumed it meant a "wet on wet" application

I thought it could be sprayed over "any sound subtrate"....... my bad
 
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You must know someone from the cruise nites or swaps that can spray them for you? Someone from a body shop?
 
I've been a licensed auto body and paint tech for 32 years, restoring Mopars for almost 40 years. I'll share some tips on bare metal and proper ways to deal with it.
As for your sandblasted fenders, first off, keep your bare hands off of them. The sandblasted metal is somewhat porous now, and the oils on your skin will contaminate the metal potentially causing corrosion wherever you have touched.
When dealing with sheet metal, you need you consider it's surface. Brand new, or nice shiny sanded bare metal is too smooth for anything to stick to well. From the factory, they use a process sometimes called bonderizing. Basically a phosphoric acid wash that etches the surface. This etched surface provides the tooth needed for primers to adhere to. So, on shiny, smooth sheet metal, use a metal prep acid, following the instructions, to etch the metal surface before coating with epoxy primer.
However, you cannot put polyester filler over metal prepped bare metal. It will react. That is why filler over epoxy primer is the best choice.
DO NOT use metal prep on sand blasted metal, because it is already mechanically etched, and porous.
Self etch primers are a primer, that has some acid in it to help adhere to smooth metal. Self etch primers really should not be used on sand blasted metal, for the same reason.
I'm not really a fan of etch primers. Filler cannot be safely applied over top because of the acid in the etch primer. Etch primer has it's place, but it's more geared for sealing bare metal that doesn't need any repair.

Sandblasted metal provides excellent adhesion for primers. Epoxy primer is your friend.
Epoxy primer comes in many variations. Slower curing products are better. Choose one that you can afford, and avoid any spray bombs. Epoxy primer is catalyzed, and once cured, most are stable and compatible with all fillers, primers and paint being put over them. I won't recommend one brand over another, but SPI, PPG DP epoxy and others similar to that are ideal.

So, with your newly sandblasted fender, put on your latex gloves, sand it as well as possible with something like 120-180 paper to knock down the texture and help remove the sand residue. Blow it off well, and wash it down with a final wipe cleaning solvent, intended for paint prep. Follow the instructions for the final wipe. Spray it with a quality epoxy primer, and once cured apply your body filler. Block sand, repeat the cleaning process, and apply epoxy primer again, before applying any filler primer.

So in a nutshell:
Properly prepared-cleaned metal.
epoxy primer to seal the metal.
filler and primer work over epoxy primer.
Cleanliness is ultra important throughout.

Always use products that are compatible.
Read and follow instructions.

This is a very simplified description. Auto body work is a complicated process, that requires skill, understanding of products, patience.

PS, as soon as you mentioned having a fender sandblasted, I got scared. Body panels can be made into scrap metal very quickly by someone with a sandblaster.
Every step from paint and rust removal, to polishing the final paint requires experience, and care. If you are new to auto body repair, I would suggest starting on less desirable-valuable parts to learn the skills.
 
I'm not a body guy, but this worked on the Coronet 500, the vinyl top was removed by the previous owner and I think he rattle can painted the roof. The paint was cracked, and there was rust around the cracked paint. Lucky it was not heavy rust. I sanded the roof to bare metal, and preped it with the acid to kill any remaining rust. I didn't like the white film left from the acid, so I just sanded that off and did a light coat of etching primer and then applied the DP40 epoxy primer. That was like 20 years ago, and no signs of rust or other paint problems.
 
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