Painting aluminum

cb34

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Anyone have any good experience painting aluminum? Looking to paint my gin pole and being told that paint holds up better than powder coat. thanks...
 

Keelboater

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IMO, paint in some forms is 100% better than powder coat. Once the powder coat begins to peel, and it eventually will, it's game over. You can't repair it. Contrary to popular belief, the ONLY reason powder coating is so popular is because it meets the strict standards for air quality when being applied - no solvents or chemicals go into the atmosphere - so fed and state regulators love it. Personally, I hate it. I once worked for a company that manufactured powder coating equipment. Think they didn't do product testing? It's all wonderful when it's new. Give it a year or two or three. I am not a paint expert so all I can tell you is to use a U.V. resisting paint and a self etching zinc chromate primer. I have had much better luck with a rattle can paint job than powder coat. Hard to believe, I know. Just be sure that whatever paint you choose, it can be repaired from damage if need be. That gin pole can see some abuse if you really use it. I'm sure there will be some good paint suggestions popping up here. Good luck!
 

Raider Ronnie

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captjohn

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The secret to powder coating is the same for every kind of paint, prep work. I had the buggy top on my tower powder coated about 8 years ago, and it looks like it did the day they refinished it. They sand blasted the hell out of it first, so the powder coating had a nice clean surface to adhere to. A friend of mine had some powder coating done and like a year later it was peeling, poor prep work. I love powder coating, but it has to be done correctly.
 

chortle

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Prep, prep and prep. Especially with metals or coatings that oxidize quickly, like aluminum and zinc.

As to powder coating, there are too many factors that go into a success or failure of a one off powder coat application. Prep is super important, the composition of the chemical bath used for cleaning (the type of chemical and how pure it is,) and etching and rinsing must be compatible with the metal and the powder. Also, the time required to get the metal uniformly up to temperature before it is sprayed is also critical. Also, the type of powder used is important. There are many suppliers of different types of powder, acrylic or epoxy based, that perform better for different applications. The acrylic based powders will hold up to sunlight very well but a scratch or a small void in the coating when applied can allow corrosion to easily migrate. Epoxy powders are much better at resisting that effect but they fade much more quickly. It can be very difficult to do well on a one off basis, whoever does it has to do it 100% right or the long term results will be iffy. Powder coating is really better left to production processes.

If it were me I would blast it with the appropriate media (sand, walnuts, whatever) chemical etch it, rinse and dry it thoroughly, immediately follow up with a primer matched to a two part polyurethane paint of your choice.
 

Keelboater

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For the most part, I believe that the powder is applied via electrostatic process before the part is put into the oven. The process of powder application to a hot part may not yield a very uniform coating and is not the safest method for sure. I have seen it done this way in "low budget" attempts with poor results. The oven time is key after the powder has been applied.
 
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Keelboater

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O.K. I took a stroll down memory lane because of this thread. The photo shows the electrostatic application of powder. The powder takes on the positive charge as it passes through the "gun" and becomes subjected to VERY HIGH voltage. The charged powder cloud attracts to the negatively grounded part. Anything that falls short of the part can be swept up from the floor or table and re-used providing the room has been kept clean between each color. Once applied and still in the un-baked stage, the powder sticks to the part much better than you would immagine. It takes a bit of effort to knock it off. No runs. No sags. Quite uniform in thickness. No solvents. No vapors. No wasted product. It's why paint has become a no-no in industry and is frowned upon by regulatory agencies. For hi volumes, these parts would pass through an oven by means of an overhead conveyor and emerge fully baked and cured. For less volume, these parts would be on a rack when coated, and then the entire rack would be wheeled into a large oven for baking. For home shops and small batches, an old kitchen oven works just fine for baking small parts. In essence, you are just plastic coating the part. There are various "formulas" of powder that may or may not enhance the binding or hardness.

EncoreMan-app.jpg



For small parts and low volumes, this Flexi-Coat system works pretty good for applying powder:

http://www.nordson.com/en-us/divisions/adhesive-dispensing/Literature/PWL/PWL1451.pdf

That's me testing the Flexi-Coat prototype back in 1998 when I was the project engineer involved with it's development. :shock: A blast from the past. I can't believe that they still have this posted on their web site! Enough about powder coating. It has it's place, but just not everywhere.

Focus on good quality paint if you want it to last and if you plan to eventually repaint your project down the road to keep it looking like new. You can't simply re-powder coat something that has already been previously powder coated, and then it's too late for paint as well. Unless it's in "a room in the corner in the back in the dark", powder just doesn't seem to hold up very well once it becomes chipped or nicked in an outdoor environment.
 
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Toolate

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What color do you want to make the pole?
 

Sailorgp

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My experience with paint of all types is the key to a long lasting finish is surface prep, surface prep and more surface prep. Although if you accidentally spill some of the paint on an area where there's been no surface prep...it's there forever...lol
 

Keelboater

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My experience with paint of all types is the key to a long lasting finish is surface prep, surface prep and more surface prep. Although if you accidentally spill some of the paint on an area where there's been no surface prep...it's there forever...lol

How true it is! Perhaps this gin pole should just get painted by accident and then it's good for an indefinite period of time!
 

Chum Pot

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Prep it till it is shinny shinny smooth new looking. Try 3 layers, a base coat, try epoxy barrier paint its a two part system and $. Then paint with a base coat of primer made for aluminum, then your color paint.
If ,or should I say when, the exterior layer of colored paint chips/wears, you always have the base layer intact to paint on. Its a lot of work and expensive paint, but it is what I have done for an aluminum deck and its just touch up of the color paint when it is needed.

option #2, just polish the aluminum and think what a PITA this project will be.
 

TCL

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Surface prep with #80 Alum oxide, Alodine, Epoxy primer, Epoxy topcoat.

Can you expand on the Alodine step? Im painting a Aluminum Radar mast.

I don't have a sprayer so I'm planning to use brushes and rollers.

Will probably use Inter Lux Perfection, but I'm open to suggestions.

IMG_0632.jpg
 

chortle

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Can you expand on the Alodine step? Im painting a Aluminum Radar mast.

I don't have a sprayer so I'm planning to use brushes and rollers.

Will probably use Inter Lux Perfection, but I'm open to suggestions.
Alodine, it's flammable and hazardous, it must be good stuff. I have not used either one of these products but they appear to be made to do just what you want to do before painting and after removal of the existing paint and corrosion products. I would sandblast that puppy and use the metal prep and alodine solutions and paint with a two part poly paint.
ALODINE 1201 from Aircraft Spruce
METAL PREP NO. 79 from Aircraft Spruce

Here is the process as specified by the manufacturer...

http://www.systemthree.com/reslibrary/tds/ALODINE_1201_TDS.pdf
 
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