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  1. #1
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    Default Rust remover or converter for tiny spots on new painted steel roof?

    One panel on my brand new painted steel roof has roughly a dozen widely scattered spots of rust that are less than 1/16" in diameter, possibly from grains of steel produced when I predrilled the screw holes, although I thought I brushed them all off and don't know why only one panel was affected. Under high magnification, I can see that the spots are tiny pits that have penetrated the paint, but probably not much farther if at all. Would you recommend a rust remover or a rust converter before painting over the spots? Which brand would you recommend?

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  2. #2
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Body shop question. Sand, seal, fill, sand, prime and then paint. Requires a cold 6 pack to initiate work.

    Have fun,


  3. #3
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Quote Originally Posted by Garry Sorrells View Post
    Body shop question. Sand, seal, fill, sand, prime and then paint. Requires a cold 6 pack to initiate work.

    Have fun,
    Thank you for replying, Gary, but it's hard to imagine that increasing the area of damaged paint by a factor of at least 10 by sanding or that risking removal of any of the extremely thin 29 ga steel would be the best option. The steel on a car is quite a lot thicker.


  4. #4
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Contact the manufacturer and ask them what they suggest. That way you will know for sure, and not rely on guesswork, and possibly wrong answers.


  5. #5
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Quote Originally Posted by Jack Feldmann View Post
    Contact the manufacturer and ask them what they suggest. That way you will know for sure, and not rely on guesswork, and possibly wrong answers.
    Thank you, Jack. I contacted the manufacturer a few days ago. They were not willing to offer any advice on repairing these tiny rust spots, except to say that trying to grind/sand the rust away would be unwise because the steel is so thin. They wanted me to replace the panel, which is of course the safest and most profitable answer for them, but not necessarily indicative that a repair would not work. Getting one replacement panel is quite disproportionately expensive.


  6. #6
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    You may have ground in the metal waste from your drilling with your foot.

    Sanding is not necessarily grinding.
    Sand the pit by hand to remove the rust. Spray some. Primer (galvanize spray/primer), then spray some enamel over that. 3 coats. Or use some brush on enamel paint with uv inhibitor in it.

    Or. Try using the rust converter then dab some epoxy on it folled with 3 coats of paint.


  7. #7
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Look up the manufacturer's installation instructions, then look for their recommended treatment of cut edges (there will always be cut edges and cut edges no longer have any manufacturer applied protection).

    Whatever the installation instructions suggest for the cut edges may well work for the rust spots caused by drilling, filing, cutting during installation. I know that all the installation instructions I've read over the years expressly warns - many times over - about hot metal sparks from abrasive cutting, grinding, drilling, etc, as the hot metal (those red sparks are red for a reason ... they are "red hot") and that they can burn through the finish coating.

    I would go with the installation instructions for treating the exposed metal at cut edges as a starting point.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  8. #8
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Quote Originally Posted by Jerry Peck View Post
    Look up the manufacturer's installation instructions, then look for their recommended treatment of cut edges (there will always be cut edges and cut edges no longer have any manufacturer applied protection).

    Whatever the installation instructions suggest for the cut edges may well work for the rust spots caused by drilling, filing, cutting during installation. I know that all the installation instructions I've read over the years expressly warns - many times over - about hot metal sparks from abrasive cutting, grinding, drilling, etc, as the hot metal (those red sparks are red for a reason ... they are "red hot") and that they can burn through the finish coating.

    I would go with the installation instructions for treating the exposed metal at cut edges as a starting point.
    Thank you, Jerry. Surprisingly, the installation instructions for these Classic Rib panels made by Metal Sales do not address how to treat cut edges, only to cut them with a nibbler. Once I deal with the rust, I expect the remaining steps would be the same as for a bare-metal edge. My main question is how to deal with the rust, specifically, which product to use. From what I've read, some converters just coat the surface of the rust to deprive it of the oxygen it needs to continue rusting, which means they will fail if there's any crack or leak in the seal, whereas others might penetrate farther and be more foolproof. A remover might also be a good option if it's safe for the paint, its residue is easily removed or readily paintable, and the steel won't start rusting as soon as it's bare.

    I'm hoping someone with experience with this problem can offer recommendations on the best products.


  9. #9
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Quote Originally Posted by Jeffrey Cooper View Post
    Surprisingly, the installation instructions for these Classic Rib panels made by Metal Sales do not address how to treat cut edges, only to cut them with a nibbler.
    Start here:
    - https://www.metalsales.us.com/reside.../classic-rib-0

    Go down to "Installation Guide Step by Step Guide for Installing Classic Rib":
    - https://www.metalsales.us.com/system...uide8-2016.pdf

    Scroll down to page 18, top of the page: "FIELD CUTTING AND TOUCH-UP", then down to "TOUCH-UP PAINT".

    Addressing the rust is an issue outside the manufacturer as the manufacturer presume that the touch up painting will be done at the time of installation (prior to rust forming) ... and, yes, I realize that this is your question, but none of our responses seem to be what you are looking for - could that be that you asked your question on an inspection board and not a metal/rusted metal board?

    Maybe start here: https://www.painttalk.com/f16/rusted-metal-roof-28354/

    Then review this information too: http://www.roofcoatingmaintenance.co...a-rusted-roof/

    And this: https://rustdoctor.com/resources/treatments/

    Those are just a few of a Google search for treating rusty metal.

    This may not be the help you were seeking, but this is an inspector's forum, not a rusty metal painting or treating forum. Hope you find the information that you are seeking.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  10. #10
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Thank you for taking the time to find those links, Jerry. I had already spent many hours reading everything I could find, among which were other discussions here of similar questions; that's why I posted here. It seems reasonable that an inspector might have seen tiny spots of rust like mine and, in order to advise clients, learned how they can be remedied without replacing panels.

    The page you refer to in the Classic Rib instructions does mention touch-up paint, but only in the context of fixing superficial scratches in the factory paint. The other links, like dozens I've read, don't quite get at this particular question, as you seem to have anticipated. Rust Doctor claims to be a great solution, as do a bunch of other rust converters; I'm just trying to sort out which products actually perform best.

    I'll look for other forums, such as Paint Talk, to try, but a lot of trade-specific forums aren't interested in helping someone who isn't one of their own. From the other discussions I've read here, this forum seems to have a more helpful attitude in general, perhaps because inspectors are in the business of assessing problems and giving advice.


  11. #11
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Naval Jelly works wonders on rust.


    www.1stproinspection.com

    Certified Master Inspector
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  12. #12
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    Default Re: Rust remover or converter for tiny spots on new painted steel roof?

    Quote Originally Posted by Roy Lewis View Post
    Naval Jelly works wonders on rust.
    Thank you, Roy.


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