Rust bleeding through primer?

[offbrandmechanic]

I recently inherited a 1955 Ford 800 and figured I'd do my best to restore it. I'm a decent enough mechanic but don't know jack about paint, primer, hardener etc. I took the time to strip the back wheels down to bare metal to repaint them. I cleaned the bare steel then gave them three light coats of primer. They ended up sitting for about a week in my shop and when I uncovered them there was rust bleeding through the primer everywhere. Is this normal? Do I have to strip the wheels and try again? Am I just a big dummy who missed a simple step? Any help is greatly appreciated.

 

[showcrop]

Unusual. What did you use for primer? Were there pits in the steel for rust to hide in?

 

[Brown David]

Most primers are porous.

 

[BarnyardEngineering]

You will need to start over. As Brown David says, most primers do not seal the metal from moisture, so in the right conditions, the metal will "flash rust" right through the primer. Seems the more "tropical" the area is the worse the flash rust problem is.

If you're not going to top coat right away, you need to put a "sealer" type paint on the metal to prevent the flash rust.

 

[rustred]

and dont cover them.

 

[stevieb49829]

Use a rust converter before you primer them this next time. Or an epoxy primer.

 

[Stephen Newell]

I recently inherited a 1955 Ford 800 and figured I'd do my best to restore it. I'm a decent enough mechanic but don't know jack about paint, primer, hardener etc. I took the time to strip the back wheels down to bare metal to repaint them. I cleaned the bare steel then gave them three light coats of primer. They ended up sitting for about a week in my shop and when I uncovered them there was rust bleeding through the primer everywhere. Is this normal? Do I have to strip the wheels and try again? Am I just a big dummy who missed a simple step? Any help is greatly appreciated.

Unfortunately the primer will have to come off. Rust has deep roots and often will continue to rust underneath the paint. There are a number of things you could do to kill the rust, you could treat the metal with phosphoric acid or a rust converter and then prime. If you really want to kill the rust use an epoxy primer. It will seal off the metal to where it won't rust anymore. Most paint and primer is porous allowing a certain amount of moisture through but epoxy primer won't Another benefit is with other paints if you ding the paint down to the metal rust will start there and spread out underneath the paint. With epoxy primer if you get a ding down to the metal it will rust there but won't spread outward. The primer is a bit of a pain to use, you mix a hardener into it as you use it and have maybe eight hours to use the primer or throw it away, time varies by brand. Then once it is primed you generally have 8 hours to put paint over the top or a sandable primer. Epoxy itself doesn't sand well at all so if there is leveling to do you put a second primer over the top.

 

[showcrop]

Guess he is not interested.

 

[jd2cyl1943]

Guess he is not interested.

He could be busy

 

[Jim.ME]

He could be busy

Or he could have been here and read the posts, without signing in, if he didn't want to comment.

 

[aleta]

I recently inherited a 1955 Ford 800 and figured I'd do my best to restore it. I'm a decent enough mechanic but don't know jack about paint, primer, hardener etc. I took the time to strip the back wheels down to bare metal to repaint them. I cleaned the bare steel then gave them three light coats of primer. They ended up sitting for about a week in my shop and when I uncovered them there was rust bleeding through the primer everywhere. Is this normal? Do I have to strip the wheels and try again? Am I just a big dummy who missed a simple step? Any help is greatly appreciated.

May I make a suggestion that I have found very useful, at either Home Depot or Lowes, you can buy a gallon plastic jug of metal prep/concrete cleaner. This chemical contains phosphoric acid which reduced 1 part prep to 3 parts water, will kill properly scraped/sanded iron surfaces. Anytime I am painting anything metal, I use this prep to treat problem rust and etch metal for excellent primer adhesion. Hope this helps, by the way, the 1 gallon of concentrated prep should cost no more than $20.00. Happy coloring!

 

[showcrop]

May I make a suggestion that I have found very useful, at either Home Depot or Lowes, you can buy a gallon plastic jug of metal prep/concrete cleaner. This chemical contains phosphoric acid which reduced 1 part prep to 3 parts water, will kill properly scraped/sanded iron surfaces. Anytime I am painting anything metal, I use this prep to treat problem rust and etch metal for excellent primer adhesion. Hope this helps, by the way, the 1 gallon of concentrated prep should cost no more than $20.00. Happy coloring!

I have been using phosphoric acid for many years. It is available at dairy supply stores as milk stone remover and at restaurant supply stores as limescale remover. $12.00 to $20.00/ gal.

 

[offbrandmechanic]

Sorry all, I have not forgot about you! I am new to this forum and couldn't remember the name till I looked back through my email. Sorry to keep y'all waiting! And thank you for the recommendations!

 

[Sberry]

I dont think the rust in pits is a big deal. If there are hi spots they need to be sanded, the paint runs off peaks.
We scuff AFTER sandblast with purple brite cause of this. It removes stuck sand and smooths it off, can feel the difference. I never use that other prep stuff, if you want it super then we use epoxy primer but it is a bit of a process to use.

 

[JD Dave]

For sandblasted or even almost totally clean metal which is perfectly clean and prepared, I've had good results using a high quality self etching primer.

 

[Sberry]

As I mention, some of the primers are thin and will poke right thru a 220 blast, we scuff after blast. Variprime is good for adhesion but really thin and not really a sealer.

 

[Stephen Newell]

As I mention, some of the primers are thin and will poke right thru a 220 blast, we scuff after blast. Variprime is good for adhesion but really thin and not really a sealer.

Variprime is mainly used for aluminum or galvanized metal. It will work on plain steel for an etching primer.

 

[Sberry]

Yes. People use it for all kinds of reasons
. It might help, it penetrated pits but runs off hi spots.
If I really want to corrosion proof it's blast, scuff, and Colar or similar primer, 2 part epoxy. Even holds some if top coats chip off.

 

[stevieb49829]

To continue this post just a bit. I need some more advice. I sandblasted my wheels on the tractor. They are a combination of cast centers and steel rims, and were rusty from chloride leaks. The rims don't leak and are still solid. Then I applied a rust converter (Corroseal), which did its job of turning the wheels deep black. Now my options are to brush a coat of good DTM white gloss as a primer (I have the paint) and then apply the final brush coat of Rustoleum (a custom blend to get the Massey Harris yellow). or skip the DTM white and go straight to the final coat of Rustoleum yellow. This is not a show tractor, but I want the wheel paint to last. Is it worth putting the white on prior to the final yellow? I was thinking yellow over the black would be harder to hide, than yellow over the white. steve

 

[SamV]

Yes Definitely put something else over the black and then go yellow. If I was you I would get Rustoleum gray primer then go yellow. I have had very good results that way just brushing my paint on wheels.