Painting galvanized panels

[Steve B]

I got a lot of steel panels, and constructed a large (32' x 40') structure out of two 40' containers. I used a lot of painted Fabral MightyRib panels, but had to use some galvanized ones, because I got a killer deal on them. Now it is time to paint the whole thing. For the galvanized, what is the best way to prep the surfaces so the paint will stick? We get blazing hot temperatures in the summer, upwards of 150 degrees surface temperature, 110 plus air temps, and 130 plus inside the containers. Winters bring weather in the 20-40 degree night time temps.

A friend of mine a long time ago, who was a professional painter, used some common vinegar to paint some for me similar to these. It was for a commercial job, and I never did go back and look at how it aged. I never got a call from the company that there was anything wrong with them, so just plain don't know if they did good or not.

Besides vinegar, is there any other treatments? Estimated 150 square feet, uneven vertical surface.

Thanks.

Steve

[hrhofmann]

Pressure wash with vinrgar, like you said, and then pressure rinse twice as long. Let set for a week or more, preferably a month or more, to weather the galvanized at least a little bit. But if it must be painted sooner, for appearances sake, I would use a good oil-based primer for starters.

[Tim Watts]

I thought etch-primer is the usual way - or is that just aluminium?

There is a paint called Rustol Deco:

That claims to go direct onto zinc - as well as ali.

I have bought some for my cast aluminium guttering so save having to do

etch-primer primer topcoat

because I am lazy...

I have not tried it yet - so I cann report on its effectiveness.

[Jim Elbrecht]

I know Krylon makes a 'Galvanized primer' -- My Ace Hardware guy goes to all the paint seminars & I'd trust him if he said there was something new out there that works better.

a real paint store *should* have good answers for you.

This is one of those times where it is infinitely easier to do it right the first time than to try to fix it when it starts to peel.

Jim

[pauloman]

old timers would just pee on the galvanized surfaces to 'prep' them.

actually nothing sticks to fresh galvanized surfaces without prep, but old weathered galvanized surfaces can be painted fine.

I would suggest something like an aluminum filled mcu coating (google aluthane) on your surfaces to reflect heat, stop rust, etc. If you don't like the finish consider it a primer for whatever colors you decide to use.

paul

[EXT]

Like aluminum, galvanized (zinc) surfaces are difficult to paint. I have read that oil base paint actually creates a layer of soap where the oil interacts with the zinc.

About 10 years ago I had to replace my rusting TV tower, the zinc had been washed off with the acid rain. The new tower was again galvanized and so I decided to paint it.

First I pressure washed with detergent to remove the oil coating, then rinsed it with diluted muriatic acid, then pressure washed it well with plain water to get the acid off.

My local Moore dealer seemed to really know his paint and recommended Moore's Industrial Maintenance Coatings acrylic metal primer which was tinted to a warm gray color.

Other than a few small chips around the base of the tower, it is still holding up well with the paint coat intact.

As in all paint jobs the prep work is important and galvanized metal often has an oil coat that must be removed before etching and painting, otherwise any finish will fail early.

[DD_BobK]

I've used this stuff with success...

Specifically meant of prepping galvanized steel for painting.

cheers Bob