aluminum prep for paint

[toplessHO]

Ive got some aluminum I need to paint white.
Im putting marine enamel on it and need something to wash it down
to remove the powdery film of light corrosion thats on it.
I really dont want to prime with zinc chromate,some of this is already installed.
What kind of acid wash or treatment will remove the corrosion and prep for the paint? Ignore the green,its paint that was used at the supply house.

 

[MFolks]

Aluma prep is sold at auto paint stores as is Alodine,both will give the paint a surface to bond with.

 

[toplessHO]

Aluma prep is sold at auto paint stores as is Alodine,both will give the paint a surface to bond with.

will it remove and neutralize the corrosion thats already there?

 

[koditten]

Can you wire wheel the corrosion, then hit it with Alodine? The Alodine will etch the Aluminum quite a bit.

 

[astroracer]

You will need to remove the corrosion. ScotchBrite pads will do that fairly quickly. Once you get it cleaned up use a self-etching primer to get a good mechanical bond. Plasti-Kote and Dupli-Color sell it in spray cans.
Mark

 

[toplessHO]

You will need to remove the corrosion. ScotchBrite pads will do that fairly quickly. Once you get it cleaned up use a self-etching primer to get a good mechanical bond. Plasti-Kote and Dupli-Color sell it in spray cans.
Mark

did you read the first post?
I have paint(qt of marine enamel),not going thru the primer thing.

 

[theoldwizard1]

You will need to remove the corrosion. ScotchBrite pads will do that fairly quickly.

Concur ! What the OP wants is something like a "rust converter". I do not know of any chemical process that will do this.

Once you get it cleaned up use a self-etching primer to get a good mechanical bond.

For the best long term adhesion if the top coat either use a self-etching primer or zinc chromate primer. I am not sure which is best for aluminum that has had corrosion.

 

[astroracer]

did you read the first post?
I have paint(qt of marine enamel),not going thru the primer thing.

Ha Ha! Yea, I read your first post... Did you read mine? I told you what you need to do. If you don't prep the aluminum you may as well just throw your paint away as it will fall off in a short time anyway...
Mark

 

[toplessHO]

spray bomb paint? reading comprehension isnt a strong point is it
So any others have some truly helpful tips?
They've taken naval jelly for aluminum off the market.
Ive tried white vinegar and some diluted naval jelly for steel.
I may try a muratic acid wipe but not sure of the concentration.
Surely theres something used in industrial applications to clean aluminum.

 

[toplessHO]

Concur ! What the OP wants is something like a "rust converter". I do not know of any chemical process that will do this.


For the best long term adhesion if the top coat either use a self-etching primer or zinc chromate primer. I am not sure which is best for aluminum that has had corrosion.

You are correct,Im looking for a converter,something like Ospho or naval jelly but for aluminum. Im not going to spray anything,too much masking,brush paint is fine.

 

[ez-duzit]

You will need to remove the corrosion. ScotchBrite pads will do that fairly quickly...

Regardless of what OP wishes for, this is the only reasonable first step, removing the corrosion.

Then Alumaprep before prime and paint.

 

[warrens]

Another +1 on Alodine solution. If I'm not mistaken, the product I've used is made by Dupont.

 

[californiaHank]

Another +1 on Alodine solution. If I'm not mistaken, the product I've used is made by Dupont.

It's actually from Henkel (German company with a big US presence.)

I painted the aluminum trim on the ports and the aluminum mast on a saltwater sailboat a few years ago. It wasn't simple - There are some good reasons that most aluminum-hulled boats aren't painted, and that anodizing is used instead of paint on a lot of aluminum sailboat masts and trim pieces.

I did my job in 4 steps:

1. Alumaprep 33 (phosphoric acid cleaner)
2. Alodine 1201 (chromate conversion coating)
3. primer
4. topcoat

Things have changed a bit since I last painted marine aluminum -

I think that Alodine is now called Bonderite. Alodine/Bonderite 1201 is not very environmentally friendly - it contains hexavalent chromium. It's still used a lot, especially on aircraft, but there may be some local restrictions on its use. I believe that there's a non-chromium (titanium?) alternative that can be used instead - Alodine/Bonderite 5200 (?). I'm no expert on any of this, so I'd ask for advice from Henkel support and/or a local boatyard that paints a lot of aluminum. I don't think there are many shortcuts - paint doesn't last long on an aluminum boat unless you do a _lot_ of careful surface prep.

 

[astroracer]

spray bomb paint? reading comprehension isnt a strong point is it
QUOTE]
Yea... I can see you are having a real hard time with that.
Good luck with your project.

 

[Elsinore13]

It's actually from Henkel (German company with a big US presence.)

I painted the aluminum trim on the ports and the aluminum mast on a saltwater sailboat a few years ago. It wasn't simple - There are some good reasons that most aluminum-hulled boats aren't painted, and that anodizing is used instead of paint on a lot of aluminum sailboat masts and trim pieces.

I did my job in 4 steps:

1. Alumaprep 33 (phosphoric acid cleaner)
2. Alodine 1201 (chromate conversion coating)
3. primer
4. topcoat

Things have changed a bit since I last painted marine aluminum -

I think that Alodine is now called Bonderite. Alodine/Bonderite 1201 is not very environmentally friendly - it contains hexavalent chromium. It's still used a lot, especially on aircraft, but there may be some local restrictions on its use. I believe that there's a non-chromium (titanium?) alternative that can be used instead - Alodine/Bonderite 5200 (?). I'm no expert on any of this, so I'd ask for advice from Henkel support and/or a local boatyard that paints a lot of aluminum. I don't think there are many shortcuts - paint doesn't last long on an aluminum boat unless you do a _lot_ of careful surface prep.

I still buy alumiprep and alodine from my local PPG auto paint supplier. It's the only real answer that has been provided in this thread so far. OP needs to read up on his marine grade finish and determine if he can get by without a primer and if his finish can actually be applied to a prepped bare substrate. Also, most non marine grade finishes can't be used for extended periods of time below the waterline. They'll blister in a short amount of time.

 

[sanddan]

Ha Ha! Yea, I read your first post... Did you read mine? I told you what you need to do. If you don't prep the aluminum you may as well just throw your paint away as it will fall off in a short time anyway...
Mark

Very true. I've used etch prime in the spray can with very good results. But I also sand aluminum so it has some "tooth" before painting. I hate to see large chunks of paint fall off, makes the project look like ****.