Trying to paint roof vent turbine with Rustoleum.

[limeylew]

I just bought a new turbine (just the top, not the base) to replace an ailing one.

It came with the galvanized finish, which was fine with me, as they didn't have a black one and I also bought a can of flat black Rustoleum, so I could make it match the others on the roof.

However, as I looked through the directions on the Rustoleum can, I saw that it said to DON'T use on a galvanized surface.

I know I have painted EMT with this type of paint in the past and not had any trouble with it.

SO, my question is, do you know why they would have this warning?

Is it because Rustoleum doesn't adhere well to a galvanized surface, or is it because it would create a toxic gas, or what?

Lewis.

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[Edwin Pawlowski]

Paint does not stick well to galvanized surfaces. There are primers made just for galvanized (zinc chromate?)steel though. Another alleged trick is to wipe it down with vinegar, but I've never tried it. You can also let it age for about 6 months.

New Galvanized Surfaces

Sometimes customers want to paint the galvanized steel surface. The first question to ask is if the galvanized is new. If it is, the surface needs to be checked for passivators or stabilizers. Many galvanized metal manufacturers, knowing that an item may be stocked or stored in humid conditions, will apply an "after galvanizing" treatment or "passivator" which will inhibit wet storage stains ("white rust"). Most sheet metal or coil stock, from which decking and curtain walls are fabricated, receive this treatment. The passivator treatment is clear so it's not readily detectable, but the Steel Structures Painting Council and the American Hot-Dipped Galvanizers Association both state that this pre-treatment prohibits adhesion from taking place. It must be removed before painting

[NickySantoro]

It's about adhesion to galvanized. If you etch the turbine with acetic acid or white vinegar, then rinse and dry, you should be OK. I've done that many times with galvanized ductwork and been ok.

[limeylew]

months.http://www.benjaminmoore.ca/howto/problems_details.aspx?problem=poor_...>

Thanks, this is very helpful.

Kind regards.

Lewis.

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[scott21230]

Can anyone here confirm that this only occurs if you use oil based paints? Meaning that latex will stick to galvanized fi you just clean it.

Having said that, I thought that cleaning and sanding (more like scuffing) is what one needed to do to get (oil based) primer to stick to new galvanized steel.

[Edwin Pawlowski]

I posted two links with information from paint manufacturers. You can either trust them, or someone's opinion on a newsgroup. Get back to us next year with an update of how well it is working.