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Rust on powdercoated(?) steel shelves

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  1. #1
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    Default Rust on powdercoated(?) steel shelves

    Fourteen years ago, I was given some Dexion 160 shelving (part of a dismantled shopfit). I assumed that a) the bits were powdercoated and b) that powdercoating was some sort of magic protection. Stored the shelves in an unlined shed. I'm half a mile from the sea.
    Recently I decided I could re-purpose some of the shelving for use in the house. Nasty shock. Extent of rust varies (depending where each shelf was in the stack) but photo gives the idea.
    Wattyl's 3-step process seems to be the go for dealing with the damage. Sand the worst off, then Killrust Rusteeter, then heavy duty primer, then topcoat matching original colour.
    It's the first stage that I'm not quite clear about.
    Sand - what with? Does Wet and dry mean I should use the paper wet? What grit should I be using? Is emery cloth better than paper?
    The surface of the rusty bits is lumpy-bumpy to the touch. I want to get it smooth before treating it, but if I do that, it will be a stipple of rust and bare metal. Is it OK to apply the Rusteeter to the mixed surface?
    I don't want to mess up again. Have no experience in dealing with metal - would appreciate a word of advice.dexion-shelves-rust-001.jpg

  2. #2
    Deactivated User Marc's Avatar
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    Wire brush, with a grinder. Then zink and top coat.
    Those shelves are made in china with bottom of the bird cage materials.
    Expect more rust. They are cheap for a reason.

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    All the pieces are stamped Made in Australia, Marc. The slotted-angle uprights, which were stored somewhere else, have no rust.
    When you say wire brush and grinder, do you mean go back to bare metal?
    And zinc(?) I'm new to this - so a brand name of some sort would help.

  4. #4
    Deactivated User Marc's Avatar
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    https://www.makita.com.au/accessorie...zNAhCjcnBszQll

    Scrape down to bare metal wherever you see rust.
    Paint the bare metal with this

    https://www.dulux.com.au/products/889H0158

    Top coat with whatever you like

    Made in Australia? Must be ancient. Good stuff,still needs some help.

  5. #5
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    Yeah, it must be over twenty years old. Grabbed it because I thought one of my brothers might want it. Neither did, so it just stayed there. Kicking myself for not checking on it.
    Thanks for the links. Job will take time, but we've got plenty of that right now.

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    If you are using a wire brush with a grinder make sure you are well covered up as the little bristles have a habit of breaking off and they end up in your skin.

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    Thanks for the word, Bros. Will have the gloves, plastic mask etc. I think I'll probably be doing quite a bit of the wire-brushing by hand. I use the grinder rarely, and I'm a bit scared of it.

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    Quote Originally Posted by Slowrenos View Post
    I assumed that a) the bits were powdercoated and b) that powdercoating was some sort of magic protection. Stored the shelves in an unlined shed.
    Very much doubt it is powdercoated rather is painted. Powdercoat would peel away with underlying rust. If you are brave enough, clean with an acid wash.

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    I'd like to try that.
    I've got hydrochloric acid, bought many years ago and used only once (yes, scared of it - you read me right, Phil), oxalic acid crystals and some CLR. One of those, or something entirely different?

  10. #10
    Community Moderator phild01's Avatar
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    Diluted Hydrochloric and washed down well quickly when rust is gone with water then metho (or prepsol) and spray with an etch primer before zinc spray. Incidentally I just used that acid now, at least wear rubber gloves, long sleaves, mask and eye protection.

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    Quote Originally Posted by Slowrenos View Post
    I use the grinder rarely, and I'm a bit scared of it.
    Nothing to be scared of with the smaller grinders you just have to know the limitations and what could go wrong as well as buying quality consumables and using safety gear.

  12. #12
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    There are twelve of those shelves - some worse than the one in the photo. Plenty of scope for trying out different methods. Thanks all for the advice and encouragement. I'll check out Youtube videos as well. Much to learn.

  13. #13
    Deactivated User Marc's Avatar
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    No etch primer. Zinc paint on bare metal. Etch primer is to paint over galvanised metal.

  14. #14
    Community Moderator phild01's Avatar
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    Quote Originally Posted by Marc View Post
    No etch primer. Zinc paint on bare metal. Etch primer is to paint over galvanised metal.
    Tell that to the panelbeaters.

  15. #15
    Deactivated User Marc's Avatar
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    The only value of zinc paint to protect from corrosion, is to act as anode in a cathodic protection system and for that it needs electrical contact between steel and zinc. It is possible to use etch primer on bare metal and then any other paint over the primer, but for the cathodic protection to work, the zinc rich paint particles must have electrical contact with steel.

    It is possible that panel beaters don't know this, or that they use cold gal due to it's epoxy binders that have good value as undercoat and forgo the anti rust properties.

    Another myth is to use etch primer over zinc paint, as if it was hot dip or duragal. This is unnecessary since zinc rich paint offers a perfectly good binding surface for any top coat, as opposed to true galvanised surface that has real challenges to be painted.

    In the case at hand, wire brushing the surface, painting with a primer and top coat with any epoxy paint is a very good alternative.
    I suggested cold gal because it is an easy insurance against further rust.

    By the way, if the OP is not confident with a grinder, sanding is a good option too, just more work. A power brush, unless you are used to wield a grinder, can catch on the edges of the shelves and kick back. Easy injury. Always wear a face shield.

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