prepping aluminum hull for paint

[PlayD0h]

I know I’m resurrecting this thread, but I’m confused as to why Alumiprep and Alodine are mainly used on aircraft, and why none of the body shops or suppliers have even heard of it.
Ive been told multiple times that sanding and priming, preferably with an epoxy primer is all that’s needed. I was told that sanding removes corrosion manually and ‘Etching’ does the same thing with an acid, Alumiprep / Phosphoric acid.
Maybe sanding an airplane is out of the question due to its size, shape, and the thinness of the aluminum. Where as a car, truck or boat sanding is more practical and cost effective?
i can get Alumiprep and Alodine for $60 (CAD) each, locally for a gallon of each. Likely 4 times more than I need. Vinegar is way cheaper and by the sounds of it used much more often.
Is Alumiprep and Alodine worth the $120, when I plan on lightly sanding the bare hull anyways? I’m likely going to use an epoxy primer, and it’s not cheap, so not wasting money will help. Yet for the same reason, if $120 helps $300-$400 in primer and paint last longer than sanding, acetone wipe, vinegar wipe, water rinse, than I’m all for it.
I likely answered my own question yet some confirmation would set my mind at ease.

Perhaps just the Alodine is a good choice, since I’m sanding and etching with vinegar?

Alumiprep etches (removes corrosion via acid) ?
Alodine protects against corrosion via chromate ?

Is a Self Etching primer reccomended after Alodine? Or under epoxy primer?

 

[Scott Danforth]

if you lightly sand the whole thing, followed quickly (within a few hours) by an etching primer, your good. I prefer a zinc chromate primer myself

aluminum oxidizes fairly quickly.

I prefer alumiprep and alodine over vinegar

 

[Woodonglass]

The alumiprep and alodine method is Prolly the BEST method however, Sanding and SE primer has proven to be quite successful by many people here on the forum. IMHO the latter will do the job and save money. In my case that is an important feature. Sometimes More money and time does NOT make the process better. This OLD DUMB OKIE does not and never has had a Tin can boat so I base this opinion on research and statements made by those who have.

 

[zool]

PPG has their own version, its what I use, DX 533 and DX 503.....so collision shops will get it from their jobbers, but its essentially the same.

 

[zool]

Also, if ur going to use an epoxy primer, then u dont need the alodyne,....its kinda an either or...wipe the metal down using a wax/grease remover with the two rag method, then sand, wipe again,epoxy prime and paint. You can use a build primer over the epoxy if u need to fair more.

 

[PlayD0h]

Also, if ur going to use an epoxy primer, then u dont need the alodyne,....its kinda an either or...wipe the metal down using a wax/grease remover with the two rag method, then sand, wipe again,epoxy prime and paint. You can use a build primer over the epoxy if u need to fair more.

Would Self Etching primer before the Epoxy primer be unwise? I do plan on priming ASAP after sanding and prepping.

 

[Woodonglass]

won't hurt but not needed.