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Woodtroll's avatar
Woodtroll
Explorer
Aug 10, 2019

Painting Galvanized Metal Roof?

It may be slightly OT here, but it's a "Tech Issue" and I'm betting someone here can help...

I put a galvanized metal (the old 5-V "tin" roof) on our farmhouse when we moved into it almost 35 years ago. I've painted it a couple times since with an alkyd enamel paint that stuck okay to the rusted parts, but sloughed quickly from the parts with zinc still on them. Now it's in dire need of painting again, but it still has some patches with zinc left on them. I'd like to paint the roof again, preferably with an epoxy or something durable, to make it last this time, even if it is expensive or time-consuming.

Has anyone had any good experiences doing this, and what product(s) would you recommend?

Many thanks!
Regan
  • Cobra21's avatar
    Cobra21
    Explorer
    Aug 10, 2019
    I have always heard to clean the new metal with vinegar prior to painting. I think this removes the oil that is on it?
    Brian
  • Woodtroll's avatar
    Woodtroll
    Explorer
    Aug 10, 2019
    Thanks, folks, I appreciate the help. I forgot to mention that my wife wants a light blue color, not silver, which rules out the usual fibered silver "tin roof" paint. This is my house roof, not a rubber RV roof.
  • jkwilson's avatar
    jkwilson
    Explorer II
    Aug 10, 2019
    Generally the problem with galvanized metal is that a layer of oxide forms on the surface which interferes with pain adhesion. You have to clean it off before you paint. It’s a lot of work, so I’d ask a knowledgeable paint dealer for recommendations for a cleaner. Likely a mild acid.
  • Woodtroll's avatar
    Woodtroll
    Explorer
    Aug 11, 2019
    Vey good information, folks, I really appreciate the help! I know that galvanized material is problematic, and I figured someone here coud help.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 11, 2019
    Dale Erb used an acid wash followed by Zinc Chromate on Quicksilver where every inch was hot-dip galvanized. Then came a green tie coat then white primer. Another painter finished it IMRON. 22-gallons worth. Silver with blue metalflake and abalone iridescence. Murals by "Cue Ball"

    Was nice when I had industry contacts and a 100K plus income back in the eighties.
  • Gdetrailer's avatar
    Gdetrailer
    Explorer III
    Aug 11, 2019
    MEXICOWANDERER wrote:
    Dale Erb used an acid wash followed by Zinc Chromate on Quicksilver where every inch was hot-dip galvanized. Then came a green tie coat then white primer. Another painter finished it IMRON. 22-gallons worth. Silver with blue metalflake and abalone iridescence. Murals by "Cue Ball"

    Was nice when I had industry contacts and a 100K plus income back in the eighties.


    DING! DING! DING!

    We have a winner!

    The KEY to success is proper preparation, the only true way to get paint to stick to galvanized metal is to acid etch then laydown an intermediate primer.

    Zinc Chromate is the intermediate primer, skip these two steps and your paint WILL be peeling shortly after it has dried.

    Learned that lesson over 35 yrs ago working on my first car from the early 1970s which the factory had used galvanized steel on the cowl under the windshield.. Couldn't get paint to stick for long until we asked the auto paint store and they sent use down the correct path..

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