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Hot Rods Epoxy primer over flash rust

Discussion in 'The Hokey Ass Message Board' started by Pats55, Jul 8, 2019.

  1. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    I think I'm losing it. In another forum advised the guy that was okay to put a zinc phosphate epoxy primer over flash rusting. Looking for some opinions. I myself would never take that chance



    um
     
  2. oldiron 440
    Joined: Dec 12, 2018
    Posts: 1,505

    oldiron 440
    Member

    Not something that I would do or have done on my car!
    The only time I would consider this is if I was planning on removing it and just holding back the rust for now, but would not paint over it.
     
  3. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,548

    anthony myrick
    Member

  4. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    I like this idea especially the metal prep and then the epoxy primer over it. And nice surfacer over it, then sealed. I use metal prep on everything the last 40 years and never had any problems.
     
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  5. oldiron 440
    Joined: Dec 12, 2018
    Posts: 1,505

    oldiron 440
    Member

    Your not to use metal prep under epoxy primer, at least not the primers I have used and I've used 20 or 30 different epoxy primers.
     
  6. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,456

    57JoeFoMoPar
    Member

    All of the rust has to be removed prior to the application of any product. Period.
     
    da34guy, Dino 64 and wheeldog57 like this.
  7. you mean we cant apply POR 15 or some other rust converter and paint over it?
     
  8. oldiron 440
    Joined: Dec 12, 2018
    Posts: 1,505

    oldiron 440
    Member

    I'm sorry I think rust converters are a joke. But what do I know.
     
    RMR&C likes this.
  9. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    I don't use epoxy primer. I like to metal prep it .I prefer my own primer with the urethane surfacer then the base then the clear
     
  10. boring-hop-yard
    Joined: Feb 24, 2008
    Posts: 74

    boring-hop-yard
    Member

    I use CRE-X21 from PPG from the PPG commercial side and I can get it much cheaper.
    It sands a lot like SPI.
    I only use CRE-X21 when I etch and SPI with no etch.
    You want to make sure the primer tech card has some sort of statement about acid that says something like this.
    This is from the CRE-X21 tech card "A chemical treatment (or conversion coating) will improve adhesion and performance properties of the finished coat"


    https://images.oreillyauto.com/parts/img/documents/ppg/cpcpb418+cre-x21+series+80513+fin.pdf
     
  11. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    Thank you for posting the product datasheet. It seems like a great product.
     
  12. boring-hop-yard
    Joined: Feb 24, 2008
    Posts: 74

    boring-hop-yard
    Member

    Your very welcome, I like the primer very much. I also like the semi gloss finish, it helps me to see what it will look like in final paint, same as the SPI. I painted my 56 f100 frame was painted CRE-X21 for the final coat since it will be under the truck and not subjected to sun light.
    Good luck on your quest!
     

    Attached Files:

  13. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    My quest has been going on for over 30 years a, hundred product data sheets from various coatings manufacturers most of the been brought up and no longer exist. I generally search for coatings that are run at least 8000 hours salt spray. My philosophy has been I want to preserve the vehicle for many years to come for future generations.Production paint jobs go just so long It doesn't make sense to me to use coatings or primers that were used years ago that failed. So all the cars that I painted had industrial primers with automotive color coats. I guess I am a little strange
     
  14. I suppose since the POR 15 and other rust converters are a NO NO! I will continue to use a wire brush on a drill and rattle can black primer on my 55 wagon.
     
  15. CRE is great stuff...you can tint it also....stuff sands like butter...it’s direct to metal...and is great for corrosion...
     
  16. Gearhead Graphics
    Joined: Oct 4, 2008
    Posts: 3,415

    Gearhead Graphics
    Member
    from Denver Co

    TAMCO does sell a primer (I believe its their galva-prime) that can go on flash rust. But preferred method is no rust.

    Give them a call, tell Tammy Jeff sent you. Shes full of info. Superior product, bargain pricing.
     
  17. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,060

    BamaMav
    Member
    from Berry, AL

    I think the rust converter paints are used more for stuff like frames and floors where they will be out of the sun since most of them don't have much if any UV protection. And some of them are hard to paint over with another kind of paint.
     
  18. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    There's a video on YouTube titled Por 15,KBS ,Chassis saver,SPI epoxy,Mastercoat Salt fog test Who went the furthest. I would post a link but I'm really not that good at it
     
  19. boring-hop-yard
    Joined: Feb 24, 2008
    Posts: 74

    boring-hop-yard
    Member

    In my work life I used to supervise salt spray test for aircraft manufacturing.
    The prep process is critical for this type of test. He talked about following the directions on the back of the can but made no reference of cleaning the metal prior to painting, what did he prep them with paint thinner, MEK, wax and grease remover, soap and water? As an example SPI recommends Bare metal is always best cleaned with 700-1 Waterborne Wax and Grease Remover and 710 Wax and Grease Remover, then let it sit 30-60 minutes before applying the epoxy! Did he make sure and wipe the surface dry before whatever he was using for prep evaporates, his test could be valid or it may not have been a fair test, anything that will block adhesion will fall victim to the salt spray test. I respect that he's trying to help by showing facts and data, my concern is the variation that was induced.
     
  20. Pats55
    Joined: Apr 29, 2013
    Posts: 361

    Pats55
    Member
    from NJ

    I agree with you wholeheartedly on surface preparation. This gentleman in the video is by no means a lab technician. I went online and checked out how to build a salt fog chamber. It's very simple device that anyone can build for just a couple of bucks.

    30 years ago after getting my tit in a ringer selling someone else's permanent rust sealer that failed I decided I wanted some facts. To make a long story short the aluminum pigmented moisture cured urethane outperformed everything in the industry for corrosion control. That's what I went with. In corrosive environments general practices is two coats of the moisture cured followed by epoxy intermediate primer and then the top coat. That's how my 55's painted.

    The biggest problem that I've experienced is all the BS associated with these paint over rust products that come in all different colors. Yesterday I was looking at a competitors product line that stated that the two component acrylic urethane painted over rust would stop it. This is the kind of BS you get from people who don't build or restore cars .As you can see this rubs my ass the wrong way.So if any of you would like to build a little chamber for testing, feel free to contact me I would be happy to send you a little product
     
  21. My52Chebby
    Joined: Jun 9, 2010
    Posts: 8

    My52Chebby
    Member

    I never understood why metal prep applications tell us to wash it down with WATER?!? I always leaves an awful rust color floating over the phosphate coating. I've started cleaning my metal prepped pieces with towels and brake cleaner, or acetone or anything but water and really like the results.

    Has anyone else tried this?
     
  22. boring-hop-yard
    Joined: Feb 24, 2008
    Posts: 74

    boring-hop-yard
    Member

    When you spray it down with brake cleaner or acetone are you wiping the surface off before it evaporates?
    I know you wipe the surface with towels but is the surface dry when you stop wiping?
    My understanding is the purpose of water is to dilute the acid.
    I'm sure someone will think my process is over kill but it hasn't ever failed me.
    When my acid treatment is done etching, I wash the part down with a Dawn soapy mix and water.
    I lightly very scrub the surface with scotch-brite to assure all of the acid is off the surface.
    I then rinse with fresh water and then immediately blow dry with clean air making sure the water does not evaporate.
    On little parts I toss them into a bucket of soapy water, lightly scrub, then into fresh water, and blow dry.
    On big parts like a truck cab I will use a pressure washer with a soap head, then a light scrub, then a rinse using a turbo head, followed by blow drying and towel dry until everything is dry. I usually have someone help drying something this big.
    If water is allowed to sit on the surface evaporate you will get flash rust.
    I have had parts sit inside storage for well over 3 years treated like this with no rust.
    I live in Oregon and we don't get a lot of humidity.
     
  23. john worden
    Joined: Nov 14, 2007
    Posts: 1,584

    john worden
    Member
    from iowa

    The key to successful acid treatment that requires a water rinse is work area prep and timing.
    After rinsing an area approx. 3'x3' or so with clean water quickly squeegy the bulk of the water off.
    IMMEDIATELY blow dry the same area with clean compressed air to bone dry.
    You may see some gold/rust colored streaks remaining and usually wiping them with a water dampened cloth followed with blow drying will eliminate it.
    Various steel alloys can respond differently to the acids and may react accordingly.
    Also do this work in low humidity conditions helps.
     

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