Zinc spray?

Discussion in 'Materials' started by parkland, Mar 1, 2014.

  1. parkland
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    parkland Senior Member

  2. waikikin
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    waikikin Senior Member

    Was just reading something the other day about zinc spray pack with Mr Zogs surf way rubbed into it as a propeller anti-foulant..... no idea if it work though.
     
  3. CDK
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    CDK retired engineer

    Carefully read the text: ...97% pure zinc...a barrier coating similar to hot dipped galvanized surfaces.....

    "Similar" is not the same, just "similar". The 3% of the coating that is not pure zinc spoils it all. There is no electrical contact between the zinc particles and the steel underneath, so there is no galvanic protection.

    After welding galvanized steel a bit of zinc spray can mask the damaged zinc layer, but that is little more than an optical illusion. Without a proper paint layer signs of rust will show after a few days.
     
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  4. Mr Efficiency
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    Mr Efficiency Senior Member

    You wouldn't think 3% "binder" would be near enough to retain any sort of integrity.
     
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  5. waikikin
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    waikikin Senior Member

    Maybe by weight:rolleyes: or maybe by volume, zinc is heavy, binders(?) maybe not so, sometimes anything can be better than nothing:D. Often I do quick removals & repairs to ships, A coat of Galmet Zinc rich primer is good:cool:... with 98.5% zinc purity & 92% zinc in the DRY FILM.... http://www.itwpf.com.au/galmet/product.aspx?productid=4

    Jeff
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    OK, it does have a SG over 7, and organic binders would be close to 1, at a guess, so the difference between weight ratios and volume ratios would be marked.
     
  7. missinginaction
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    missinginaction Senior Member

    I use a very similar product. Generically it's referred to as Cold Galvanizing Compound. This stuff is used to prevent corrosion on things that sit out such as chain link fences, ornamental wrought iron, things like that. I use it on car brake drums, rotors (not on contact areas) and suspension parts to combat the effects of road deicing salt.

    I don't believe these products would work as a primer or below the waterline. The zinc will abrade from a surface fairly easily.
     
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  8. parkland
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    parkland Senior Member

    Maybe not for under water line, but inside the hull it seems like a cool product especially for hard to reach spots.

    Seems like you couldn't go wrong trying it anyways.
     
  9. SamSam
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    SamSam Senior Member

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  10. parkland
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    parkland Senior Member

  11. kerosene
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    kerosene Senior Member

    I have used such spray - its not very robust. Rubs off easy as there is so little stuff to keep it together. That time I was reading more about them and some people had pretty good experiences in places where there isn't much mechanical wear.

    Really it needs paint on top.
     
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  12. parkland
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    parkland Senior Member

    Thats pretty much what I envisioned about the product.
    That it would have low adhesion strength, but hey, it is
    zinc, so it's gotta do something.

    If it was used to coat the inside of the hull, even tiny particles that
    wear off and sit in the bilge would still help protect against rust, wouldn't
    they?
     
  13. Jeremy Harris
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    Jeremy Harris Senior Member

    I've used a similar "cold galvanising" paint for years, Galvafroid, for protecting outdoors stuff, but never on a boat. I have a slightly rusted steel padlock (that had originally been zinc plated) that locks up my workshop. Back in around 1995 is started to rust, so I brushed on a coat of Galvafroid. That padlock is still pretty much rust free now, nearly 20 years later, and has been on my workshop hasp all that time.

    Despite this endorsement I don't think the stuff would work below the waterline on a steel boat. For protecting the internal steel surface though I think it would work very well indeed.

    The downsides are that the cans of the stuff are really heavy, and you cannot get a good cosmetic finish with it, as it has a high solids content ( all that zinc powder I guess). It's also pretty expensive, or was the last time I bought a tin (which was a few years ago now).
     
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  14. SukiSolo
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    SukiSolo Senior Member

    I have heard of shot peening with zinc prior to painting as a corrosion inhibitor. Not used it myself so can't judge it for marine use. Have used zinc paints for auomotive part protection with reasonable results. they are not as severe as marine though.
     

  15. Easy Rider
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    Easy Rider Senior Member

    I modified an anchor by substituting a different fluke tip w on of my own design. I was in Alaska at the time and didn't have access to a galvanizer or a good selection of steel.

    The original fluke tip was much more conventional …. very pointed as seen in the first pic. It was SS.

    My different fluke tip (second pic) was of mild steel and I coated it w what I recall as "Cold Galvanizing" in an aerosol spray can.

    Went on a long boat trip (Ketchikan to Seattle) and used that anchor most of the time. It looks a slight bit darker now but to my amazement no rust at all. The oaring worked better than I could have imagined.
     

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