I know that most people here just take a rattle can and paint, that is fine, but I am getting ready to repaint the dominator and was wondering if anyone had any good luck with painting aluminum, Arnie?
I have painted cars and motorcycle etc for many years, and working in the aircraft industry I have painted some aluminum and know the procedures.
First the part should be de smutted, I.E. remove all the oxidation with smut remover...
Then it should be acid etched with phosphoric acid, rinsed with water and then dipped in an alodine solution,
Followed by a fresh water rinse and then painted with an epoxy primer.....

That is a lot to do for a homebuilder...I have obtained some aerospace impact resistant epoxy primer, as well as some very nice urethane topcoat.

My question is would scuffing the aluminum with scotchbrite, and then wiping with acetone before primer,
would the paint still stick well enough?
I do not want the paint to peel like most of Ernie's paint jobs do over time.
I may just be over thinking this, I mean it is not like it is going to the moon or anything.

Input?

Short answer is: No
Long answer is: NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

AL is highly oxidizing element that you can NOT get rid of the oxide unless working under conditions that are oxygen free.
There are certain chemicals that make aluminum oxide paintable though....

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Quick answer first .... a fast and hassle-free paint job on aluminum is just fine .... but the one step I would never eliminate is the alumiprep (Phosphoric acid) and water rinse. That is the key to everything.

Skip that step and all the cleaning or scuffing in the world means nothing.

Longer answer in my next post , how and why I did what I did when painting aluminum . (I liked to do it as fast as possible , and as easy as possible , and have the paint stick forever)

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Waiting with pregnant anticipation....

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The aluminum I painted was always bare , either brand new or completely stripped of the old paint ... and because it had been handled , set on work benches , touched by bare hands , drenched in drilling-cutting oils I would ...

Wash the parts with warm soapy water ... I used good old ordinary Sunlight dish soap in the yellow bottle , dont use soap for soft hands , it has oil in it. I also took care to wash any cutting oils from inside square or round tubing if any machining or drilling had been done.

Then dont touch it with bare hands (oily) or set it on work benches (oily greasy dirty) , or wipe it with old greasy shop rags

Not always necessary but often I would scuff it with a Scotchbrite pad or fine sandpaper to give paint and primer a bit more tooth , or to knock down any tiny nibs or nicks. Significant scratches I would dry sand out with my orbital sander and 180 grit .... (I would never sand aluminum on a certified aircraft skin ... technically it could lose its certification)

Most important is the Alumiprep Phosphoric acid treatment ... it chemically cleans the surface of the aluminum and makes paint stick forever. Nothing else will work. Leave everything else out but not this step. Rince well ,air dry , and prime or paint . Again , make sure not to touch it with bare hands or anything oily or greasy.

Often I just used a clean cloth to apply the alumiprep , but sometimes scrubbed a bit with a scotchbrite pad as well , main thing is to remove the invisible oxidizing film from the surface , then rinse well.

One of the best ways a guy can prove it to himself is to take a scrap piece of aluminum , try wiping it with a cloth with just water on it and you can swirl it around and wipe it forever .

But add some alumiprep to the water and the aluminum becomes so clean the surface friction is so high you can barely move the cloth anymore.

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Thanks that is the info I was looking for, Aluma prep is no problem, other than just lots of parts....the alodine is where it gets to be a pain in the butt, out here at the airline we have huge vats of the stuff..
If it was 15 years ago, I would have just brought all the parts to work, and etched then and alodined, and then sent them to the paint shop....but alas, things have changed, not so easy to do things like that anymore.
Thanks Arnie!

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If I am uber-fussy I pay the most attention to the areas around drilled holes etc ... those are the places where bolt heads and tightening nuts will make the paint come off in big flakes. On a properly etched and painted surface a nut or bolt head may grind some of the underlying paint away , that is normal , but it should not flake off around it.

Around bolt holes I will first make sure there are no drill-burs on the edge of the hole , often I will do a light sanding in those areas just to make sure , then alumiprep and paint. I also like to do a light sanding on sharp edges where the aluminum has been cut , just a light pass to remove the knife edge .

Stuff that tricks a guy is cleaning everything then eating a sandwich with mayonnaise in it and touching the parts afterwards , mayonnaise is half oil , or eating KFC for lunch then touch the parts with the greasy hands , or any trace of armor-all or silicone in the shop , cutting oil residue inside tubing , it creeps out around bolt holes ... all those contaminants act as a release agent between the metal and the paint.

Know what is the hardest part for most guys ???? .... it is having a quart of alumiprep sitting on the shelf for the day you need it. The average guy does not have it , and that is why it becomes easy to say ... "skip that part' .... "brake-clean will work" .... "acetone will work" .... "clean it with gasoline my dad said" .... my little sister said my grandmother knew somebody who used vinegar and it worked .... my other grandmother said "use lemon juice" ... Haaaa .

In spite of all this rambling ... Alumiprep is fast and easy . If I had an 8 foot 2"X2" mast to paint I could walk into my shop , put 2 ounces of alumiprep in a cup of water and have the whole thing wiped down and rinsed 3 minutes . Its just that easy.

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Thanks Arnie, Having painted cars etc, I do understand the cleanliness part. !

My biggest thing is I will have to plan my day around the painting, cleaning the parts, hanging them etc, then after priming I have to topcoat the parts within 24 hours for the paint to properly bond to the primer, and with, mast, keel, tail, landing gear parts etc, cheek plates, lots of small parts and lots of prep time. I may not get to it this weekend, but soon I hope.
I can't just paint a couple parts after work each night etc, too much waste on the 2 part paint.

The alodine should not be necessary if you are painting it ... alodine is mostly a protective coating for stuff that is NOT being painted . If you are in a lot of salt water or something you might want alodine on the interior of the parts (inside the tubing) (hidden interior parts of commercial aircraft) ... I would never alodine-coat gyro components , nothing to gain unless interior corrosion is an issue , and I doubt it on a gyro.

The hard part (pain in the ass) for you is your gyro is assembled , or at least partly assembled , cheek plates , brackets , riveted-on parts etc.

You have a lot of area to swab down with the alumiprep , you have to turn stuff around and upside down , you have to try keep everything "wet" with alumiprep until the final rinse with clear water , not always easy to do , then when you are all done there will be water trapped inside some tubing , in edges around brackets , stuff like that , can be a real pain but it will give the ultimate job in the end,

I would use compressed air to blow everything off (dry everything) and then let it sit and air-dry for quite a while after that before prime or paint. A couple of drops of water rolling out of a tube mid-paint will have you recalling all your favorite swear words from when you were a sailor. I have never been a sailor but I still know the all the cuss words HAAA.

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Looks like we were typing at the same time .... and yes , all that is the pain in the ass stuff , I am a tight-ass and try to use as little chemical as possible , and like you , hate to waste activated paint , so I hear 'ya loud and clear

For a lot of small parts and brackets you could have your alumiprep & water mixture in a small plastic container and just dip the parts , maybe a quick wipe or scrub and then have a mama - gyro around to rinse them and hang them ,

I use scotchbrite or 1200-1500 paper on frame tubes (wet) then dry with clean paper towels, then either spray with an etch primer (which ruins the top few microns of the tube, but sticks like shit to a blanket) or else if the tube is really new, scotch brite, dry with paper towels, then I use ESP (no, not mind control) a product called 'Easy Surface Preparation'

It is clear and looks like thinners... you wipe it on with clean towel or paper towel, wait 90 minutes for it to dry, then just primer.... with ESP, paint sticks really well, without actually etching into the alloy

I will be wrapping mine.... but not right to the cheek plates, about half inch from the plates... I like to see if there is any cracking or witness marks... not have them covered by paint/powder/wrap....

You can actually get colored 'carbon fiber look' it even comes in Fuchsia?

The best thing about wrap, is you can change it... just peel it off and change color

The paint shop I get my esp from always remember me..... When I first went in there... I stood their with my knuckles on my temporals and stared at a wall... the lady from the paint shop asked what I wanted?

I just turned and looked at her and said.... "If you have what I need, you shouldn't have to ask we what it is??"

She turned and was about to run and hide or call the cops.... and I said "do you have ESP or not?"

They always remember me for that

Now when I go in there, they put their fingers on their temporals and then say..... "its on the shelf" (pointing at the esp

I buy a 500ml can for $18.... if you buy big cans, if you don't use it like within a year (or 6 months) it tends to go to jello in the can.... I would rather buy 2 x 500ml cans than 1L