cast iron wood stove outside - prevent rust/waterproof

ksul Posted By ksul, Jul 13, 2017 at 12:39 PM

  1. ksul

    ksul
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    Jul 13, 2017
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    hi there not sure what my options are i have a wood stove we use at the edge of a gazebo put it does get hit with rain. i have painted the steel part with stove paint but dont like the look for the cast part. ive tried stove polish which delays the rust coming on but eventually i get rust again as it gets rain on it occasionly. is there a waterproofing product i can use that will take the heat but keep the look of the cast? i do tarp it when cooled down to minimize the amount of rain it gets

    any suggestions?

    - Kevin
     
  2. begreen

    begreen
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    Paint probably is better, but heating accelerates oxidation so I fear this is a losing battle.
     
  3. ksul

    ksul
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    Jul 13, 2017
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    Thanks I guess I'll just have to do touch ups throughout the season and move it under a roof at some point

    What about the "chrome" part any suggestions on it

    I'm not even sure if it is chrome or not
     
  4. coaly

    coaly
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    Stove polish allows water through and is the reason why old cast iron needed to be re-coated weekly. Extremely difficult to remove for paint after it has been heated.
    High temp paint is more impervious to water but outside it must be primed with high temp paint as well. That is what high temp primer is for. Exterior use.
    Check out the Stove Bright Products.

    I maintain outdoor steam equipment such as traction engines, rollers, steam shovels and worked on locomotives. Many parts get protection with cooked on steam oil, smoke boxes (the front of locomotives and traction engines) is the worst since they use coal which gets fly ash turning to lye on them. That's an extreme environment that gets lots of primer and painted yearly.

    Normally the "chrome" is nickel plate. Nickel hardens with heat, chrome peels right off with heat. Nickel finish is first plated with copper for adhesion. You'll notice black under chrome on peeling bumpers. That's due to copper under layer for adhesion, nickel for color and chromium for hardness. Oven racks are a good example of nickle plate without the chrome finish.
     
  5. WoodyIsGoody

    WoodyIsGoody
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    Jan 16, 2017
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    We let ours go au natural (but it is all cast iron):

    20170708_210141.jpg

    It's looked like this for the 15 years we've had it out in the weather. Sometime before we acquired it the previous owner had given it a coat of rust colored paint. Welding a sacrificial zinc anode in an out of the way place would slow the rust down. Some steel/iron is better than others at getting and maintaining a rust patina. I think on an outdoor stove, trying to prevent all rust is an exercise in frustration.

    If you want it painted I would use Ospho first. It's just a dilution of phosphoric acid. The phosphate in the acid converts the rust, ferric oxide (Fe2O3), into iron phosphate (FePO4) and water in the reaction:

    Fe2O3 + 2 H3PO4 ® 2 FePO4 + 3 H2O

    What was rust will now be a well-adhered hard black coating. If not protected, it will rust again when wetted but this is a good final prep for rusted metal before paint or primer. I've never tried this on anything that gets as hot as a woodstove but it typically extends the life of the paint many times.

    Remove all loose rust with a wire brush. Wipe down with a damp terrycloth rag. Put down something to protect the surface underneath. Use a cheap brush with natural bristles to stroke the dilute phosphoric acid up the rusted surfaces. They will turn black almost immediately. When it is almost dry repeat once or twice to ensure all the rust is converted. After the final dry it is ready for primer or paint. But most stove paint will not handle the hottest portions of a well fired woodstove anyway. But it might look better than what you have.
     
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  6. ksul

    ksul
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    Jul 13, 2017
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    Thanks for the info appreciate it... your chimnea looks great!
     

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