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I have some large galvanized metal disks that I going to grind into an outdoor decoration.

Grinding will destroy the zinc covering. It'll be painted afterwards.

How can I weatherproof the metal?

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  • Be careful when grinding zinc. To protect workers, OSHA has set an average legal limit of 1 mg for zinc chloride fumes and 5 mg for zinc oxide (dusts and fumes) in workplace air during an 8 hour workday, 40 hour work week.atsdr.cdc.gov/phs/phs.asp?id=300&tid=54
    – David D
    Apr 19, 2019 at 17:41
  • Thanks @DavidD. I'll only be doing a little bit and outdoors but I'll wear a respirator anyway.
    – BanksySan
    Apr 19, 2019 at 19:42

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i've been decorating some metal mailboxes which have been outdoors for 1.5 years and are still looking good.

the process

  • i started by removing old paint/lacquer that was about to fall off. i did this by mounting a wire wheel brush on my drill and brushing the mailbox.
  • next, i cleaned the mailbox with white spirit followed by cleaning it in water and drying it.
  • i applied several layers of molotow spray paint.
  • i used molotow actrylic pens for drawing illustrations on top.
  • finally, i applied three layers of clear spray paint for outdoor use.

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You said that you will be painting the ground galvanized metal. If you use outdoor weatherproof paint, then you will be weatherproofing your material for the length of time indicated in the tin.

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  • As there are so many formulations around, perhaps a paint especially designed for use on metal outdoors would be worth considering? Especially if you are near the sea. Look for something designed for metal fence or a steel corrugated roof. Some paints also have anti rust-chemicals added. I'd talk to the people at the paint desk. Remember that these often come in a spray can for small jobs.
    – Stefan
    Mar 31, 2019 at 4:14
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If you are grinding galvanized metal, for "final finishing" I quickly found 5-10 methods on YouTube and Instructables that give some relatively easy solutions. "How to galvanize metal" was my search string.

I've been investigating electroplating steel. aka de-rustification.

Galvanizing is an interesting anti-rust technique. Most galvanizing is hot dipped, in a vat of molten zinc.

But using a zinc anode, zinc oxide electrolyte, and a steel item = electroplating (OUTSIDE - allow H2 gas to escape & not explode) is quite easy. No super nasty chemicals needed either. Happy re-surfing (researching) and investigating

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Depending on the type of paint, it should form an able enough barrier. Fun fact, to prevent the rusting of large, steel, salty sea-faring boats, they connect large blocks of zinc to teh hull on the inside. The zinc "protects" the outer steel layer by basically transferring the corrosion to it (there's a lot more chemistry involved but that's basically what happens).

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