# powder coat aluminum failing.



## DeanV (Apr 18, 2007)

Working up a price to touch up some entry gates that are Al and powder coated. In areas, the powder coat is peeling down to bare metal and both the bottom od the paint and the metal look to have a white colored powder on them that does not brush away. Does anyone know the cause or the cure? They want a touch up but that of course would not be a cure.


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## 4ThGeneration (Apr 17, 2007)

Tell them the touch up will not happen because unless you have the batch and sheen of what powder coating was used thats out the door.

Best way is to remove all flaking paint to a smooth surface. If there is rust at all then you need to treat the rust with ospho. You can brush it on. It will stop the rust in its tracks and keep it from coming back.

Primer- Epoxy primer for ferrous metal because I assume it is iron?

Finish- Alkyd Gloss Exterior

Entire gate system needs it because if its already peeling and such the entire coating system has already taken great damage. It will fail entirely one day.

If not, hit them with the spot scraping, priming and touch up and warranty nothing. Not ever touch up. Give them some packages to look at so they can get into the process.


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## VanDamme (Feb 13, 2010)

> Tell them the touch up will not happen because unless you have the batch and sheen of what powder coating was used thats out the door.


Why not get a color that's real close. Match the sheen (of course), and get the color rack out and hand match it?


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## Retired (Jul 27, 2010)

By "Al" do you mean the gates are powdercoated aluminum? If you are seeing rust (iron oxide) this may be from the hinges, handles or locks that could be steel. Aluminum outgasses and will push paint including powdercoat away from the substrate unless properly primed. 

Not a clue what that white powder might be. IMO the first thing to be sure of is what the gates are made of, what steps were accomplished to apply the "powdercoating" and go from there.


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## DeanV (Apr 18, 2007)

The gates are Aluminum, the hinges are steel. The steel is rusting, but I can take care of that. It is the Aluminum that I do not have figured out. I will try to find the pictures on my phone and post them later. I have called the door company who had me call the metal work company who gave me the number for the powder coater (still have to call them).


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## Painter Girl (Mar 25, 2009)

I am no expert on aluminum but I do know that when it begins to oxidize it turns white and eventually can scale over. It can bleed just like rust once the coating is compromised. You should be able to use Penetrol by Flood to remove the residue to prep it for painting. It is sometimes used to prep aluminum for coating in the marine industry.


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## Schmidt & Co. (Nov 6, 2008)

That white powder is aluminum rust..... (yes, aluminum can rust)


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## Retired (Jul 27, 2010)

DeanV said:


> The gates are Aluminum, the hinges are steel. The steel is rusting, but I can take care of that. It is the Aluminum that I do not have figured out. I will try to find the pictures on my phone and post them later. I have called the door company who had me call the metal work company who gave me the number for the powder coater (still have to call them).


Sounds like you may be getting the run around and a high phone bill as well. If the steel hinges are rusting through the powdercoat and the powdercoating is flaking off the aluminum, it sure sounds like somebody dropped the ball or just got away with a single application of powdercoating with little or no regard to any priming at all. 

May be best to let the customer talk to the door company, the metal work company and then the powdercoater. Know that those gates cost a bundle. 

Aluminum primer is zinc chromate.


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## 4ThGeneration (Apr 17, 2007)

Everybodies sheen is different, so to get it as close as possible you would have to sample many paints to do that and I am sure its not in their budget. You could ask where they bought the gates or who the installer was and find out if they have a document on what was used and then go from there.


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## DeanV (Apr 18, 2007)

*picts*

Here are a couple pictures of the failure on Aluminum FWIW


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## Ranger72 (Jul 3, 2010)

The aluminum is oxidizing. If they are just wanting a 'low price/ quick fix' then grind/ sand the problem areas to get all the loose paint back. Then sand the aluminum until all the oxidation is gone (it will look shiny). You can then paint it which ever process it is that you use. A one step deal would be http://www.benjaminmoore.com/bmpsweb/portals/bmps.portal?_nfpb=true&_windowLabel=contentrenderer_1_10&contentrenderer_1_10_actionOverride=%2Fbm%2Fcms%2FContentRenderer%2FrenderContent&contentrenderer_1_10cnp=public_site%2Farticles%2Fproduct_articles%2Fpa_ext_metal_coatings_professional&contentrenderer_1_10np=productcatalog%2Fproduct_pages%2Fpaint%2Fprd_z163&_pageLabel=fc_productsspecs#recommended_for

(I would still use stix or some sort of proper primer with the above)

You could also use Stix to prime first then any of the following:
http://www.benjaminmoore.com/bmpswe...ges/paint/prd_164&_pageLabel=fc_productsspecs

http://www.benjaminmoore.com/bmpswe...ges/paint/prd_363&_pageLabel=fc_productsspecs

http://www.benjaminmoore.com/bmpswe...es/paint/prd_c163&_pageLabel=fc_productsspecs


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## TJ Paint (Jun 18, 2009)

Ranger72 said:


> The aluminum is oxidizing. If they are just wanting a 'low price/ quick fix' then grind/ sand the problem areas to get all the loose paint back. Then sand the aluminum until all the oxidation is gone (it will look shiny). You can then paint it which ever process it is that you use. A one step deal would be http://www.benjaminmoore.com/bmpswe...3&_pageLabel=fc_productsspecs#recommended_for
> 
> (I would still use stix or some sort of proper primer with the above)
> 
> ...


i wonder if there's a waterborne superspec dtm like the alkyd you posted a link to.


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## Retired (Jul 27, 2010)

DeanV said:


> Here are a couple pictures of the failure on Aluminum FWIW


Good shots of those failure areas. I'm sticking to my story on priming aluminum if you go with touching up. Ironically, "Stix" is available from Home Depot.. An auto paint supply will have a rattlecan of zinc chromate for about ten bucks. Also one of those paints by BM is a heat resistant paint containing alumimum. 

Back to square one, or in this instance circle one. See where that powdercoating is coming off? IMO, that is from moisture running down that reverse curve and laying in a puddle on the bottom of the circle for who knows how many cycles. The moisture is going through the powdercoat, the aluminum is oxidizing, outgassing and pushing the powdercoat off the substrate. I don't see any evidence of any sort of primer only the oxidation. 

I'd still be talking to the outfits that did the work originally for a complete re-do. The gates look fairly new. Even a small hole at the bottom of each circular element would have allowed drainage. 


Famous aluminum story.. A car mag got a sample of some aluminum from a famous 1930's GP car. Arranged to have it analyzed by an eminent metallurgist..(story says he was from MIT) They shove a mike in the guys face and ask him about the wonderment of the alloy. He tells them the alloy is about the same as they would find on lawn chairs from Kmart. (or Home Depot)


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## NCPaint1 (Aug 6, 2009)

TJ Paint said:


> i wonder if there's a waterborne superspec dtm like the alkyd you posted a link to.


Yep http://www.benjaminmoore.com/bmpswe...ges/paint/prd_m28&_pageLabel=fc_productsspecs


Its available in Semi-Gloss as well in the Industrial line


Metal & Wood Enamel is basically the same as DTM and available in low lustre

http://www.benjaminmoore.com/bmpswe...np=productcatalog/product_pages/paint/prd_363


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## Ranger72 (Jul 3, 2010)

Oops on the one paint. I was rushing, thought it was a different paint than that.

Just, sand, stix it and put some latex low luster iron clad on it.


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## 4ThGeneration (Apr 17, 2007)

They could have had quality control problems at the plant and moisture got in during the process. Those areas are very minimal, so yes, just prep it and touch it up with a coating in the color closest to it. Take a sa,ple chip to your local paint store. Explain to the owners that unless they want to do it all that some agreement has to be made that the sheen may be a bit different as well as color because you are actually matching a faded color as well.

*SCOPE OF WORK, CONTRACT AND WORD IT ALL OUT*


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## Retired (Jul 27, 2010)

The cure aka stoving temps of most powdercoating applications are near or exceed the boiling point of water. 

http://www.michianaimpreglon.com/powdercoating.htm

Hard to tell if any fading has happened. A pic of an area not exposed to weathering contrasted with an area exposed to the weather would be an indicator.


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