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Kynar vs. Powder coating

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Q. I have four cast iron bollards scheduled to be installed (exterior) at our Harlingen Campus.
The department wants a Kynar Finish. I believe that a Powder Coating will provide an equal if not better finish and will last long.

I need data that I can use to prove my opinion. Can you help?

Tom J deleted
University - San Antonio, Texas


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A. Dear Tom:

Kynar is PVDF based coating which is guaranteed for 20 years of environmental exposure. Normal powder coatings are nowhere near it - to the best of my knowledge. I am afraid, you may not find what you are looking for.

Gurvin Singh
Coatec India -

Mohali, Punjab, India



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A. Hi Tom,

With the correct pretreatment and application, powder coatings are available with a guarantee for 25 year environmental exposure. These powder coatings have been available for a long time and are common in Europe. Hope this helps.

Drew Devlin
- North Lincolnshire, U.K.


June 4, 2009

A. PVDF or Kynar being a brand name, is a coating that can carry a lengthy warranty relating to color & gloss retention. A schedule of loss is applied to the product. Mechanical failure is generally not part of that. Warranties never apply to steel products. My advice is to sandblast the item white, handle minimally with clean gloves, Zinc prime, checking substrate temperature, powder coat with a finish product of SD quality polyester or TGIC free Sd polyester. Read any warranty. The 7 p's apply to powder coating. Prior Proper Planning Prevents Piss Poor Performance. Also know that Kynar or PVDF is not usually the recommended product on traffic & heavy contact areas by the reps I have dealt with. This comment is a personal opinion & not extended as fact.

Sheldon Pineo
- Fort Myers, Florida


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Q. Would any one tell me more details about "Kynar" & its application..... thanks


Atul Bhide
jobshop / applicator - Mumbai, India


February 12, 2008

Q. Is Powder coating on steel as effective as on aluminum for preventing corrosion and maintaining color uniformity and luster? Exterior exposure.
For how long?

joe mercolino
ceilings - Los Angeles, California


February 13, 2008

Hi, Atul. Kynar is a powder coating, but it is thermoplastic rather than thermoset, and usually applied at far greater thicknesses than typical thermoset powder coatings. I have only seen Kynar coatings applied at one shop, so I am not really an expert on them, but they were applied from a fluidized bed rather than by electrostatic spray; my book knowledge supports that this is the typical approach.

Joe, please read Drew's entry very carefully because it implies some stuff that experts like him realize, but most people don't: it's all about the pretreatment! If appropriate and high quality powder coatings are applied to properly pretreated materials, the durability will be excellent. But no matter how exotic the paint or powder, if the pretreatment isn't good, the coating will be crummy. Steel parts require a well done phosphatizing step and possibly electropainting before powder coating. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

June 28, 2008

Q. What is the difference between thermoset and thermoplastic treatment for powder coating?

zia ullah khan
- Dubai . U.A.E.


July 2008

A. Hi, Zia. Thermoset plastics are plastics that cure into a different state than they started in. Sort of a one-way street. Once they are set they can never return to their original condition, you can't usefully melt them. Thermoplastic materials are plastics that soften with heat, repeatedly. If you formed a block of thermoset plastic, it would stay in that shape forever; if you formed a block of thermoplastic material you could, in theory at least, form it into a different shape the next time you applied heat.

When it comes to using these plastics in powder coating, the biggest differences seems to be that thermoset materials can be thin (a few mils) whereas thermoplastic coatings are much heavier; and thermoset materials are usually applied by electrostatic spray, while thermoplastics are usually applied by fluidized bed.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

February 5, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Difference between PVDF, polymer and polyester coating? I am new in metal roofing industry and I would appreciate if anyone can enlighten me on the above differences and advantages.

Thanks in advance.

Tommy Kang
- Singapore


.

Hi,

PVDF fluoropolymer based coatings are suitable for corrosion protection and making up to 15 mil film thickness. Teflon is a largest manufacturer of this type of coatings. Best luck.

D Kalyan
Calcutta, Mumbai, India



July 25, 2013

Q. We are considering the use of steel metal cladding and roofing paneling with a Kynar 500 finish for some small utility buildings in an industrial process facility. What are the effects of fluorides, both particulates and gaseous, on Kynar 500 coating? Can we expect the coating to last 5 years, 10 years? Maximum levels of particulates 12,500 ug/m3 per 24-hour period.

Randy Hansen
- Phoenix, Arizona, USA
  ^- Privately contact this inquirer -^


July 29, 2013

A. Yes, if installed properly and well maintained it should last 5-10 years, maybe a little longer per BS4994. Halar (ECTFE) might be better but it is fairly expensive.

blake_kneedler Blake Kneedler
Santa Clara, California

August 8, 2013

A. This thread is a little convoluted, so I answer what appears the central question. Kynar is a PPG trade mark for a PVDF resin system. PVDF is a fluorocarbon based polymer which when it comes to things like weathering properties is at the top of the food chain. This is why many architects specify it for buildings. Polyester is more of general purpose resin system used for more mundane, less critical, painting. Powder coating is paint that is applied without the use of solvent, though different resin systems can be used, including polyester.

When it comes to things thermoplastic to thermoset you learn quickly if you have a chemical like MEK on your hand don't pick up a phone or a plastic stopwatch, no chemical resistance.

Ronald Zeeman
coil coating - Brampton Ontario Canada



Powder Coated Aluminum vs. Galvanized Metal with Kynar for Commercial Railings in Coastal Environment

May 20, 2014appended

Q. We are looking to install new railings at a hotel in the harsh coastal environment on the Monterey Peninsula, California.

We have a lot of linear feet of railing (so cost/value is a consideration) and I'd like the railings to be modular or built off-site and we can "simply" install on site.

One architect has recommended a modular, powder coated aluminum railing product, and another architect has recommended galvanized metal with Kynar paint.

I'm concerned by some images I've seen of the powder coat flaking off on aluminum. I have no experience with Kynar.

Any thoughts or recommendations? THANK YOU.

Greg

Greg Alden
- Monterey, California
  ^- Privately contact this inquirer -^


May 2014

A. Hi Greg. I think you can pick the railing material you wish (galvanized or aluminum), independently of which final finish you want (Kynar or a more mundane powder coating). I think I'd mix-&-match and go with the Kynar on the aluminum. But Kynar on galvanized should last the better part of forever.

A point we should continue to repeat in case there are any newbies reading this posting is that pretreatment is critical -- not only will the paint not stick properly to the aluminum if not pre-treated well, it will pull off the galvanizing in sheets :-)

Zinc phosphatizing is required for the galvanized, and chromate conversion coating for the aluminum. Best of luck.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

May 21, 2014

Q. Thank you for your response.

With powder coating, I understand that you can't easily "repaint" it or touch it up if it gets scratched or if color palettes change in the future.

With a product like Kynar, can we paint over the original if we want to change the color in a few years or if it gets scratched or worn out?

Greg Alden
- Menlo Park, California United States


May 2014

A. Hi again. Anything can require touch-up, and consequently there are touch up materials for either finish, although the touch-up may not have the durability and longevity of the oven-cured finish. Repainting of either to accommodate color changes is probably a pretty big deal, best avoided, but farmed out to experienced parties if necessary. Firms who offer both, like the site's supporting advertiser, Southern Aluminum Finishing, can probably advise the details of repainting the various finishes.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
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