# Garage Door Prep and Kynar



## mmpaint (Nov 29, 2019)

A customer who is an hour away called and wants me to paint their garage door. I recommended Stix primer, because it should stick to anything, right? And it is rated for metal, which the garage door is. So I happened to look at the TDS on Stix and it says don't use it on Kynar, unless you do an adhesion test, which I really can't do since the job is an hour away. So I researched Kynar, and I'm not finding anything on how you can TELL if a surface has Kynar or not. Does anyone know? And what primer do you recommend if not Stix? From what I'm seeing, looks like Kynar could be on a lot of things. We need to know how to deal with this to avoid future problems.


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## RH (Sep 7, 2010)

I have no idea what Kynar is (didn’t bother to google it). 


I think you might be overthinking this. If it’s a metal door, clean it well and then paint. If it’s wood, prep as you would pretty much with any wood surface. No need to prime unless situation demands it.


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## mmpaint (Nov 29, 2019)

This is what Stix TDS says:

 Not recommended over Kynar® (and similar finishes) unless
tested and approved by the buyer

And also this:
Always test questionable substrates such as
plastics, composites, Kynars, and polyester surfaces by applying a
small area for adhesion and top-coat compatibility before
proceeding with the entire job

it is a factory coating for metal garage doors and windows, etc. I've seen where several people had failures when painting garage doors, but didn't see a definitive fix or reason. It may be it was because it was a Kynar finish


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## Redux (Oct 27, 2018)

Although I haven’t tried it, I’m wondering how UMA Advanced Technology Primer Sealer Bonder would work?

Most prep specs call for using 3M synthetic 000 steel wool abrasive pads with soapy water, in order to remove the factory applied wax followed by rinsing and conducting an adhesion test first.


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## Joe67 (Aug 12, 2016)

Perhaps ask the HO to find the manufacturer labels for the door and shoot you pictures of it. Then see if you can get the technical info on the factory coating from the manufacturer. This way you can find out about the Kynar (of which I also know little).


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## mmpaint (Nov 29, 2019)

The house was built in the late 80s or early 90s, and the HO isn't the first owner, so I doubt they are going to have any information from the door manufacturer


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## Joe67 (Aug 12, 2016)

mmpaint said:


> The house was built in the late 80s or early 90s, and the HO isn't the first owner, so I doubt they are going to have any information from the door manufacturer



There's usually a manufacturer label on the door or tracks somewhere.


Mine are from the late 90s. Never did anything to them so never looked. But I've got a manufacturer, phone and serial number


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## mmpaint (Nov 29, 2019)

I'll see if I can get that information. And if it is Kynar, or for future jobs, still need to know what will safely cover it.


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## SS_painting (Jan 11, 2020)

Why not use a quality DTM exterior paint?

If the door is from the 80/90s then it's most likely to be painted at least once, maybe bring a couple gallons of bonding primer too just in case it's an alkyd. 

Sent from my SM-G950W using Tapatalk


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## Joe67 (Aug 12, 2016)

mmpaint said:


> I'll see if I can get that information. And if it is Kynar, or for future jobs, still need to know what will safely cover it.



Like SS_painting my first thought was a DTM


You do have to clean the heck out of it either way.


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## mmpaint (Nov 29, 2019)

I had thought about DTM, but my first thought was that DTM is really made to apply directly to metal, and of course this already has a finish on it. I thought Stix would stick to almost anything, so I thought I was covered. But then I read about the Kynar, and now I don't know. Is it beneficial to apply DTM to metal that already has finish on it? Does anyone have any good info on this?


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## Redux (Oct 27, 2018)

mmpaint said:


> I had thought about DTM, but my first thought was that DTM is really made to apply directly to metal, and of course this already has a finish on it. I thought Stix would stick to almost anything, so I thought I was covered. But then I read about the Kynar, and now I don't know. Is it beneficial to apply DTM to metal that already has finish on it? Does anyone have any good info on this?


Sherwin Williams DTM Bonding Primer is recommended by a couple of overhead door manufacturers for use over Kynar, silica polyester, and polyester baked on coatings. The prep spec usually calls for cleaning with TSP or a soap of sorts, using a 3M synthetic 000 abrasive pad followed by rinsing. 


https://www.sherwin-williams.com/document/PDS/en/035777281734/


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## CApainter (Jun 29, 2007)

Redux said:


> Sherwin Williams DTM Bonding Primer is recommended by a couple of overhead door manufacturers for use over Kynar, silica polyester, and polyester baked on coatings. The prep spec usually calls for cleaning with TSP or a soap of sorts, using a 3M synthetic 000 abrasive pad followed by rinsing.
> 
> 
> https://www.sherwin-williams.com/document/PDS/en/035777281734/


I've used a SW coating system spec'd for Kynar that included the Bonding primer and top coated with Shercryl. It adhered well, but the Shercryl faded more than I would have liked within a shorter period of time than I would have expected.


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## mmpaint (Nov 29, 2019)

Redux and CApainter, that's really good info. Thanks so much. Interesting about the Shercryl, but any paint is ok as a topcoat, right?


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## Joe67 (Aug 12, 2016)

mmpaint said:


> Redux and CApainter, that's really good info. Thanks so much. Interesting about the Shercryl, but any paint is ok as a topcoat, right?



I'd say yes. I like MoorGard / MoorGlo depending on whether you want less/more sheen, respectively.


But I stand to be corrected.


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## Woodco (Nov 19, 2016)

Youre overthinking it.... Get a good quality exterior paint, (or DTM) bring some 123 if it needs some spot priming.


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## Redux (Oct 27, 2018)

I do recall a not so recent thread involving two back-to-back paint failures on a factory finished metal garage door where the door wasn’t primed. The original poster shared an Instagram video of the first failed attempt by the HO where the failed coating was being removed and blown right off with just a pressure washer. The original poster indicated having cleaned it on the 2nd go with simple green followed by a 100% acrylic w/out priming which failed for yet a second time, resulting in a warranty call back. The photos posted from 2nd failure showed the finish coming off in sheets, the acrylic paint having poor adhesion over the factory finished metal...thinking that a bonding primer compatible over Kynar and polyester couldn’t hurt..also following DASMA’s prep spec using the 000 synthetic pads saturated with a soap of sorts to clean them..


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## hasnazameer (Jul 20, 2020)

Apply good quality exterior paints.


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## Ric (Oct 26, 2011)

mmpaint said:


> A customer who is an hour away called and wants me to paint their garage door. I recommended Stix primer, because it should stick to anything, right? And it is rated for metal, which the garage door is. So I happened to look at the TDS on Stix and it says don't use it on Kynar, unless you do an adhesion test, which I really can't do since the job is an hour away. So I researched Kynar, and I'm not finding anything on how you can TELL if a surface has Kynar or not. Does anyone know? And what primer do you recommend if not Stix? From what I'm seeing, looks like Kynar could be on a lot of things. We need to know how to deal with this to avoid future problems.


Here's the problem MM... Kynar (and Hylar) are essentially the same construction. These are examples of fluoropolymer coatings referred to as PVDF (polyvinylidene flouride)...they are a resin structure similar to a Silicone Polyester, and are very, very...very hard to paint - unless you recoat with a similar chemistry (Teflon is an example of a fluoropolymer resin). The results you'll get with DTM, OMU's or UMA's are sporadic - at best, and the repair, if they don't work, is monstrous. PVDF coatings are very tough & durable with exceptional adhesion, weatherability, stain and UV resistance - they are generally baked finishes, but some manufacturers now have an air-dry version that performs very well on a baked PVDF coating. The good news is, if you decide to paint this the right way - you can make a ton-o-money. PVDF coatings may run anywhere from $140 - $400 per gallon, and some manufacturers may insist on you completing an application course to purchase the product. Sherwin makes one called Fluropon (which I believe is technology they acquired when they purchased Valspar), and PPG makes Coroflan - which I believe are both sold over the counter - and both Kynar (or Hylar) resin (Kynar/Hylar is not a finish paint, but rather the original PVDF resin, invented by DuPont and currently manufactured by Arkema). Most of these Kynar containing coatings are guaranteed for 30 years not to fade, chalk or peel...(these coatings have been around since 1948, btw).

My recommendation would be to study up of fluoropolymer coatings, and avoid the often-times-futile temptation to return a PVDF surface back to an inferior, conventional paint system.


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## Woodco (Nov 19, 2016)

My takeaway from Rics post is to walk away from kynar doors....


Seriously though, what about using auto primer?


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## mmpaint (Nov 29, 2019)

Thanks for all that good information Ric. Two things, can you always know if it's Kynar, and also what about the DTM spec sheet that says for use on Kynar? Do you think it's accurate?


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## cleaningguy (Aug 14, 2020)

everything sounds good


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