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letter 39523

Powder Coat Failure on Aluminum Railings



A discussion started in 2006 & continuing through 2017 -- add your Q to bring it back to the Hot Topics page.

(2006)

Q. I am a General Contractor that installed powder coated aluminum railings at balconies for a multi story ocean side condominium building (the building is about 100 yards from the ocean). About five or six months after completing the project the powder coated finish began blistering and flaking. Now almost one year after project completion there appears to be a "white chalky" corrosion on the aluminum rails where the powder coat has flaked off. We contacted the railing fabricator, who also did the powder coating and installation of the rails, and he claims that powder coating is not an appropriate finish for aluminum railings in a coastal environment. He says that a Kynar finish should have been specified. The specifications were not very detailed and they only say "provide aluminum railings with a powder coated finish". The railing fabricator obviously knew the building was ocean side because they field measured the balconies before fabricating the railings.

I need advice as to whether properly applied powder coating is an acceptable finish for these ocean side aluminum railings, and if so, how can I prove that the fabricator did not properly apply the powder coating, or properly prep the aluminum before coating. All advice appreciated.

An additional question: Does anyone have a suggested means for prepping and refinishing of these rails in place, as opposed to complete removal and replacement of the rails? The corrosion on the base aluminum is not significant. The condominiums are located in northern Florida, on the Atlantic coast.

John Sloan
General Contractor - Nashville, Tennessee, USA


(2006)

A. A year or so ago there was a letter and series of responses on an almost identical situation; try using the search engine and you may be able to locate it.

If I recall, the responses basically broke down to this: powder coating CAN do the job, but isn't necessarily the best finish without other steps being taken also (such as anodizing underneath the powder) and saying that the finisher "obviously knew because of xxx" doesn't mean nearly as much (legally speaking) as saying "the purchase order specified xxxx".

Good luck.

Jim Gorsich
Accurate Anodizing Inc.
supporting advertiser
Compton, California, USA
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 Ed. note: Thanks for the reminder, Jim. Letter 34235, "Powder Coating Rusting Dispute", is probably the one you are referring to.



October 19, 2014

thumbsdownMY 2-CENTS ... DISGUSTED WITH THE INTEGRITY, CRAFTMANSHIP & QUALITY OF POWDER COATED FINISHES. WE ARE ALWAYS BEING SOLICITED FOR REFINISHING ALUMINUM RAILING ON OUR BEAUTIFUL SHORES HERE IN PALM BEACH. WE ONLY ACCEPT CLIENTS THAT ARE TRUE TO THEIR PROFESSION, OR REALLY WANT TO MAKE A DIFFERENCE. THERE ARE MANY POWDER COASTERS AROUND. I TRUST NONE! YOU HAVE TO WALK THE PRODUCT THRU THE POWDER-COATING COMPANY'S PRE-TREAT & BAKING SYSTEM OR THEY WILL CUT CORNERS.
ALSO ... FOR THE OPTIMAL ADHESION ON AN EXTERIOR ALUMINUM SUBSTRATE, MY EXPERIENCE TELLS ME THAT A LIGHT ETCHING VIA SANDBLASTING OR PRESSURE WASHING WITH SAND INJECTION IS A MUST PRIOR TO POWDER COATING (PRIMER)! THEN OF COURSE OTHER NORMAL REQUIREMENTS HAVE THE COATERS PRE-TREAT TO RINSE - LET DRY IN OVEN AND COAT PROMPTLY AND FOR AN EXTRA 10 MINUTES. SO MANY TIMES I HAVE HAD PRODUCT DELIVERED WITH FAILED COATING BECAUSE IT WAS NOT LEFT IN TO BAKE LONG ENOUGH. NOT TO LET IT SIT OUT OVERNIGHT SO IT CAN GET ALL DUSTY ! HEY MAYBE WE SHOULD OPEN UP A REFINISHING CO!

GLENN SIMMONS
METAL WORK - WEST PALM BEACH, Florida


June 1, 2015

A. John,

Powder Coat over aluminum, if done properly, is an excellent finished product that will last for years, even in a coastal environment. My professional experience would lead me to believe that the railings were not properly prepped before the powder coat was applied. Pre-treatment errors will always show up as field failures. Also, you mentioned chalking. This is caused from using the wrong powder, plain and simple. Epoxy powders, though excellent for chemical and corrosion resistance, will chalk within 4-6 months of UV exposure. I would suggest for future projects that your company always hire a coatings consulting firm to perform process audits on your suppliers. This insures proper documentation and accountability are established in the event of a failure. Some consulting firms also offer proper coating selections for projects. Finally, it sounds like you have to re-finish what your supplier did incorrectly. For in place fixing, every square inch of rail will need sanding. Then apply a 2 part polyester wet paint for marine applications. Hope this helps and remember, always have process audits done on your coating suppliers by a professional. The cost is far less than field repairs.

Christopher Lucy
- Hurt, Virginia USA



August 15, 2017

Q. Our powder coat has failed on seven main posts of the deck rail. The contractor suggested that there could have been water in the posts which froze and as a result expanded the posts. We drilled a small hole at the base of the affected posts and, sure enough, out poured a significant amount of water. How it got in there is hard to imagine, and why weren't there weep holes for this?

39523-1a   39523-1c   39523-1b  

At any rate the rail is 10 years old and the guarantee is no longer in effect. We feel he should bear some responsibility for this. What is your opinion?

Dorothy Layer
- Burlington, Washington


August 2017

Hi Dorothy. People don't like to jump into contract disputes, but neither your cars nor appliances, nor anything else I can think of has an appearance guarantee exceeding 10 years; I am rather certain that no car or appliance manufacturer would entertain any "responsibility".

But I don't think the expansion of water turning to ice, expanding the posts, could possibly cause such peeling. Fresh powder coating has more flexibility than that. I think it's just the age of the paint/powder; I've seen powder coating last much longer and I've seen it last much shorter.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


August 16, 2017

Q. My curiosity is how the water got into the posts. As to who could be "responsible" for that. We can't figure out why it was there. It was around a half gallon of water in each post. We are not attempting any restitution, just desire answers.

Dorothy Layer
- Burlington, Washington


August 2017

A. Hi again. If you'd like to send pictures of the tops of the posts maybe someone can guess, but I can't tell from what you've sent so far whether the posts extend all the way to the roof, or are only waist height with plastic caps on their tops, or whatever. Thanks.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


August 16, 2017

Q. The rail is waist high. Seems to be no way water could get in, but the posts were bulged out a bit and actually burst at the edge seam (if you look closely you can see). So we deduced the freezing theory was true.

39523-2c   39523-2b   39523-2a  

We have sanded them down and used JB Weld on the seams, then just spray painted them for a short term fix. They look good again. Any idea WHY water would be in them?

Dorothy Layer
- Burlington, Washington



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