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Old 08-12-2005, 06:15   #1
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Powder coat paint?

I have my furler apart for repair and I would like to repaint it before I put it bach together. Does anyone know how well powder coat paint holds up on aluminum in a saltwater enviroment?
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Old 08-12-2005, 07:15   #2
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Powder coating should work well in your application. Powder coating painting, eliminates volatile organic compounds (VOCs), hazardous air pollutants (HAPs), and solvents, and produces a tougher surface finish than ‘wet’ painting (due to higher cure temperatures*). Proper surface preparation (i.e., cleaning and conversion coating /w chrome phosphate) is required to develop a good coating adhesion substrate. Thermoplastic powders (polyethylene, polyvinyl, nylon, and fluoropolymer) are most suitable for thicker, more durable coatings.

* Caution: Aluminum extrusions require lower cure temperatures than typically used on steel.
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Old 08-12-2005, 14:10   #3
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Given a choice I would powder coat any metal exposed to the marine environment. A proper power coat that passes aircraft standards must not deteriorate under high temperature hydraulic or other oils for a certain period of time. Most coatings will not pass this test.

Powder coating is quite resistant to scratching. I have had some ordinary mild steel powder coated and if you can keep it from being dinged or scratched so badly that the powder coat is removed from the surface it would be better to use than any stainless steel.

You cannot powder coat over aluminum which has been anodized.

I have been involved with several boats which have had their Edson pedistal parts corrode, including the shifters. After removing all of the paint and having the various parts powder coated, including the stainless steel steering wheel, there was never again a corrosion problem. I just don't understand why Edson doesn't get a clue and powder coat their parts from the factory.
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Old 08-12-2005, 15:05   #4
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Sinced you have to do a conversion coating before applying powder coat, why not just anodize and let it go? Powder coating is good but not as tough as a good anodize job.

A good plating shop can do the anodize and you can even get color.

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Old 09-12-2005, 07:05   #5
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Thanks Gord. I will call the local paint shop today.
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Old 09-12-2005, 10:47   #6
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No tie coat needed for powder coating

Not only is a primer or any tie coat not needed for the powder coating process it is excluded becuase powder coating requires that charged particles be attracted to a very clean metal conductive surface. If any "first coat" exists then the particles will not migrate or adhere to the surface.

Powder coating is more resistant to corrosion than is an anodized surface.
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Old 09-12-2005, 17:03   #7
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Powder coating, as good as it is, it still more prone to cracking, chipping, abrasion, and peeling, than a good anodize job. Why are aircraft parts anodized instead of powder coated? Because it is a better corrosion resistant treatment.

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Old 09-12-2005, 19:28   #8
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Powder coating has to be baked on (350º), that's why it's not used on aircraft parts. It could change the properties of the metal. Also powder coating is mainly exterior uses. Most aircraft parts are internal. The skin and wings are painted though.

Besides powder coating adds thickness, can be up to .025" on flat materials, but averages around .002" - .010". Where aircraft parts are machined to size then anodized, which only adds .0002" - .0004". Plus aircraft is not generally used around salt water, with the exception of seaplanes of course. But I'll bet they are inspected more often then not!

I've always wondered how a powder coat would hold up on a deck winch. My old ones have some kind of coating but haven't been able to identify the stuff yet. They seems to have a ceramic based paint, like Belzona, but thinner. Don't Know?

Powder coating

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Old 10-12-2005, 06:44   #9
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Powder coating is undoubtedly a fantastic protective finish, but does suffer from one problem. once the powder coating has been breached, (scratch or ding) it is very difficult to touch up satisfactorily without taking the piece off, grit blasting and starting again with the powder coat.
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Old 10-12-2005, 12:49   #10
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I anodise a lot of my own parts. But anodising a mast etc I would not do. ( Apart fom not having the facilities. ) But anodising, although it is a tough surface, is still easy to scratch and once scratched, can't be repaired. Easily anyway. Plus the process of anodising eats into the top surface of the Alloy, This altered surface layer has no real strength copared to the overall strength of the rest of the structure. So you are effectively reducing the thickness of a spar and thus it's strength. OK, it's a thin layer, but you get what I mean.
Powder coating, as stated, is think. It adds a lot of weight. The material is initially tuff and hard to damage. But it is a form of plastic, that once it breaks down in UV, it becomes a nightmare. You can't just touch it up or recoat it easily.
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Old 10-12-2005, 14:20   #11
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How long will powder coat last in the tropical sun?
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Old 10-12-2005, 18:12   #12
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Aircraft and powder coating

Here in the greater Seattle area several powder coating shops cater to Boeing and have since at least the 80's (those shops which can adhere to Boeing's aircraft standards). Someone is sadly mistaken that powder coating is not used in aircraft. ONE reason IS that it is more corrosion resistant than is anodising

IT will hold up very well in the tropical sun
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Old 11-12-2005, 04:07   #13
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I didn't say powder coating is not used on aircraft. I did say they frequently anodize aluminum and not add other coatings. I built aircraft parts for decades so I am not making this up as I go along. I also did powder coating. While not a chemical engineer I have been intimately involved with both processes. I have never, however, powder coated aluminum.

Anodizing is light weight, very corrosion resistant, does not appreciably affect the strength of material. The application we are discussing is not high load, but depending on the alloy, curing temperatures for powder coat can adversely affect material strength.

In the 80’s I dove on a WWII Japanese bomber in Truk Lagoon which had been underwater for 40 years. The skin was bare anodized aluminum. It was in amazingly good shape. 40 years in salt water. That’s good stuff.

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Old 15-12-2005, 08:08   #14
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Ijust got a price to powder coat my parts. $30.! I can not paint in any other way.
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Old 26-01-2006, 07:49   #15
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I recieved my parts back yesterday and reporting that it turned out great. It cost $30. for sandblasting and $20. for the paint. They used a automotive UV paint and they said it will hold up for years. It was a very good way to go.
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