Slapping some paint on a metal surface can be a real pain if you think that aluminum or whatever can be treated the same as wood. A metal roof or manufactured homes are two cases-in-point.
One plus: When you cover metal, you don’t have to worry all-that-much about the color you’re painting over. Just make sure you follow all manufacturers’ directions.
Slapping some paint on a metal surface can be a real pain if you think that aluminum or whatever can be treated the same as wood.
Just what is galvanizing? It’s a process where the metal receives of coat of zinc. This causes the zinc to bond with the steel. You’ll find galvanized materials on roofs, downspouts, gutters, ducts and vents. When weather does its magic to the substance, oxidization occurs. This leftover is called “white rust.”
Galvanized metal is one of those surfaces that are very testy because of said oxidation. Getting uneven results should be expected. However, there are things you can do to lessen the negative issues that seem to run hand-in-hand when painting a galvanized product.
By not properly preparing hard or smooth surfaces you’re headed for a failure. For one thing, there’s nothing for the paint to stick to because the texture doesn’t allow it. And an unclean surface offers another barrier. You need to remove any loose paint, grease, dirt or oil.
Is your main coat compatible with your primer? What about the drying time of the primer? You don’t want to apply so much primer on the first day that you won’t be able to, on the second day, cover with your main coat.
Those who make galvanized metals create a variety of different grades. Bonderized, galvanized materials are paint-ready. It’s been treated with a special coating that decreases the possibility of paint not sticking to the surface. Then there’s this thing called spangle size. The only thing you need to know about this quality is that you’ll get better “stickage” if your spangle size is small.
3.Temperature And Other Failures
Galvanized materials that have undergone a chromate treatment are paint problems from the get-go. The reason that the substance was coated with a chromate treatment was to inhibit the growth of “white rust.” No matter what you do, paint will have a big problem sticking.
Materials that are in an environment where weather extremes occur on a regular basis are prone to cracking and peeling. Think of putting a coat of latex on an inflated balloon. After the paint dries and the balloon deflates, see what happens?
People who wash galvanized steel with acid or vinegar solutions report that the failure rate of this process is unacceptably high.
Additionally, alkyd primers cause a chemical reaction between the zinc in the galvanized steel and the fatty acids in the paint. What ultimately happens is that by applying an alkyd primer, zinc soaps are created after a while.
Galvanized steel that has been sitting there for years experiences a loss of the zinc on the surface. This leads to rust and corrosion. Talk to your hardware sales person about what kind of primer they’d recommend in a situation like this.
Any solution that’s chosen must be watched. Not constantly, but you might want to clean it a couple of times a year. Water, bleach and a liquid detergent will work just fine.
Metal is not the easiest material to cover. Like any project, proper planning, preparation and procedures lower the needle on the “fail-meter” to levels that read “success.”