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Old 12-20-2016, 12:27 PM   #1
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Default Painting galvanized metal

After thirty two years in this business it still amazes me that painters can't get it through their heads that no legitimate paint company or representative thereof is going to stand behind the use of alkyd paint and primers on galvanized metal. So why do painters still insist that it is the best and ONLY thing to use on galvanized? Unless it is a primer specifically made with cement in it, (a type of product rarely seen outside of severe industrial applications nowadays due to voc restrictions.), there WILL at some point be a reaction between the alkyd components and the zinc in the galvanized treatment. Unless the idea is to sell constant maintenance to your end customer you are using a product that seriously shortens the life of the coating.

Every single time a customer of mine has a problem with painted galvanized metal, EVERY SINGLE TIME it is caused by the alkyd paint that was used. Even silicone alkyds do not provide the longevity of a proper DTM coating. You can take that to the bank as it is supported by every reputable paint manufacturer there is. With the exception of some fairly exotic and new products that is. But at the price those products are going for I seriously doubt they are being used on normal painting jobs. Certainly NOT the ones I am seeing.
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Old 12-20-2016, 02:47 PM   #2
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Get an automotive grade primer for use on galvanized metal, then paint. Otherwise, PAC is right; it will fail.
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Old 12-20-2016, 03:05 PM   #3
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just say no people, just say NO!
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Old 12-20-2016, 03:14 PM   #4
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I think the reason painters like using alkyd based primers on galvanized sheet metal, is because they can bypass the correct preparation methods to remove the fabricating oils (or passification as I understand it). The alkyd based primers will immediately adhere to unprepped sheet metal. Unlike waterbornes that will immediately peel once dried if the surface oils weren't removed.

However, many painters don't realize that the alkyd continues to harden over time. It's when it can no longer tolerate the expansion and contraction of the sheet metal that it begins to fracture. And with concrete and other types of galvanized metals, saponification doesn't begin to occur until some time later. About the time the warranty is up.

Once again, without oversight, or concern for that matter, the good or the poor "painting product" will look identical to one another when first applied. And it will look indistinguishable during the period one receives their check. Eventually, the integrity or lack there of, will certainly reveals itself. That's what's insidious about this business. How do you compete against the rampant deceit inherent in this trade?
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Old 12-20-2016, 03:49 PM   #5
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Originally Posted by CApainter View Post
I think the reason painters like using alkyd based primers on galvanized sheet metal, is because they can bypass the correct preparation methods to remove the fabricating oils (or passification as I understand it). The alkyd based primers will immediately adhere to unprepped sheet metal. Unlike waterbornes that will immediately peel once dried if the surface oils weren't removed.

However, many painters don't realize that the alkyd continues to harden over time. It's when it can no longer tolerate the expansion and contraction of the sheet metal that it begins to fracture. And with concrete and other types of galvanized metals, saponification doesn't begin to occur until some time later. About the time the warranty is up.

Once again, without oversight, or concern for that matter, the good or the poor "painting product" will look identical to one another when first applied. And it will look indistinguishable during the period one receives their check. Eventually, the integrity or lack there of, will certainly reveals itself. That's what's insidious about this business. How do you compete against the rampant deceit inherent in this trade?
Exactly! If i had a dime for every time a painter around here used SW alkyd industrial enamel on galvanized I'd retire. The prep issue is a very overlooked aspect of this problem.

My biggest issue is that the big gas station maintenance companies and whoever is building all of the new gas stations around here use alkyd exclusively. Mainly for the "ease" of surface prep (as incorrect as it is!) and the ability to use one product on almost everything. I can pretty much tell you who painted when I see the paint coming off the galvanized roofing and awnings in sheets after a few years. Then the owner just calls them back to do it again.

Every major fast food franchise in the country has figured this out a long time ago. Unfortunately some of the franchisees would rather throw their money at the painting instead of following spec.

And here's the bind I'm in. I'm trying to compete to be a supplier to these same painting contractors, So I can't go willy nilly to the property owners and tell them how badly they are getting screwed! Well I can actually if i want to kiss any potential sales to those painters away.
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Old 12-20-2016, 07:32 PM   #6
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I thought the issue of painting galvanized metal was settled years ago.
When I had a new AC system installed about 7 years ago, the new line-set was mounted on the exterior of the brick wall and covered with galvanized metal.

Following what I assume is standard procedure, I cleaned the cover with lacquer thinner and applied 2 coats of acrylic satin exterior (no primer). In 7 years there has been no cracking, peeling or loss of adhesion.

That's system I'm gonna stick with.
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Old 12-21-2016, 09:46 AM   #7
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Originally Posted by slinger58 View Post
I thought the issue of painting galvanized metal was settled years ago.
When I had a new AC system installed about 7 years ago, the new line-set was mounted on the exterior of the brick wall and covered with galvanized metal.

Following what I assume is standard procedure, I cleaned the cover with lacquer thinner and applied 2 coats of acrylic satin exterior (no primer). In 7 years there has been no cracking, peeling or loss of adhesion.

That's system I'm gonna stick with.
yup. A good exterior 100% acrylic is typically all you need if it is prepped properly. That's my point. Why would they say they absolutely have to use alkyd?

This post was caused by my having a customer come in with a piece of galvanized flashing asking me what I had that would stick to it. He said he has to have it painted every 3-4 years and since it's around the roof area on a two story house he has to hire someone to come and paint it. I asked what they had been using and he brought the can in from his car. SW alkyd Industrial enamel. He said the last several painters he had hired told him that was what they HAD to use on galvanized to keep it from rusting. To which I replied, "it's galvanized and it shouldn't rust bad enough to need a rust inhibitive paint". I told him that there is no reason why they couldn't use a good exterior acrylic, (I even mentioned Durations as a possibility) and he thought I was nuts. I told him if he never wanted to have to get it painted again to use the P&L High Performance Acrylic metal primer and a DTM topcoat, and he said he would check with his painter. Now what do you think the painter is going to use? The same thing they've been using all along.
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Old 12-21-2016, 12:41 PM   #8
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Quote:
Originally Posted by PACman View Post
yup. A good exterior 100% acrylic is typically all you need if it is prepped properly. That's my point. Why would they say they absolutely have to use alkyd?

This post was caused by my having a customer come in with a piece of galvanized flashing asking me what I had that would stick to it. He said he has to have it painted every 3-4 years and since it's around the roof area on a two story house he has to hire someone to come and paint it. I asked what they had been using and he brought the can in from his car. SW alkyd Industrial enamel. He said the last several painters he had hired told him that was what they HAD to use on galvanized to keep it from rusting. To which I replied, "it's galvanized and it shouldn't rust bad enough to need a rust inhibitive paint". I told him that there is no reason why they couldn't use a good exterior acrylic, (I even mentioned Durations as a possibility) and he thought I was nuts. I told him if he never wanted to have to get it painted again to use the P&L High Performance Acrylic metal primer and a DTM topcoat, and he said he would check with his painter. Now what do you think the painter is going to use? The same thing they've been using all along.
Even the SW Urethane alkyd requires a primer for galvanized metal. However, the Galvite HS, that SW recommends, is a modified alkyd acrylic.
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