What kind of primer for bare aluminum?

[Salty Cracker]

Hello folks.
I have my rescued jon boat stripped and waiting for refinishing.
There is some of the factory finish left around rivets and inaccessible crevices.

I would like to spray both the primer and topcoat.

 

I've done quite a bit of searching here and elsewhere and it seems to come down to 3 options; epoxy, self-etch and zinc chromate.
Any info that I can find from the forum search seems to turn up threads that are fairly old so I suspect their may be new info on the market.
I think self-etch is out because it may lift whatever paint is still left.

 

The boat will only be used in fresh water and trailer kept.

 

I don't want to imply that cost isn't an issue but I like to spend my money and labor once. So quality and performance is my main concern.

Please advise.

[Dogface]

I used zinc chromate on two or three I did. I never had an issue. 

 

Prep is important. I forget how I prepped the boats but did as instructed on the can. 

[Salty Cracker]

Thank you.

[Catt]

Surface Preparation of Aluminum for Painting

Sand paper: 80-100 grit

Scotch-Brite Hand Pads: part # 7447

Conversion coating: acid etch primer/Alodine/Chemfilm

Paint: automotive or marine grade polyurethane

Paint & Coating Stripper: Eldorado Solutions' DoradoTM Industrial Products part # 2021 or 5051

 

Steps

010: Clean the aluminum surface with a good cleaner using Scotch-Brite Hand Pads to remove all dirt, old paint and oxide from the surface. When sanding I prefer 80-100 grit it gives better tooth and paint adhesion.  Sanding must be taken into the best previously adhered surface in order to have the new coat of paint hold properly. Start with an orbital sander; finish by hand with Scotch-Brite Hand Pads. Rinse thoroughly with clean water & let dry completely.

020: Apply a coat of acid etch primer following the mixing and application instructions to the letter.

030: Within 24 hours of applying the etch primer, apply the topcoat finish.

[Teal]

^text book^

[WRB]

On June 8, 2020 at 11:39 AM, Dogface said:

I used zinc chromate on two or three I did. I never had an issue. 

 

Prep is important. I forget how I prepped the boats but did as instructed on the can. 

Zinc chromate paint is banned in most states for over the counter sales. 

Tom

[Salty Cracker]

Thanks for the replies.

I tried my best to talk a local industrial marine coatings Sherwin Williams into selling me zinc chromate but I got the brush-off.
I ended up using Rustolium self-etch primer with pretty good effect. Even though I put quite a bit of effort into removing most all of the factory coating, leaving behind only what refused to come off, the primer did end up lifting just very small amounts of the factory finish that was left behind. I solved that by hitting those spots with a small wire brush and getting bare aluminum in those spots this time. I spot primed those areas and am now waiting for the rain to stop so I can do my top coats. I hope I don't regret it but I plan on using Rustolium "professional" oil base. Hunter Green.
I'm leaving the underside of the hull bare aluminum since it'll see fresh water only. That's okay isn't it? Bare aluminum in fresh water?

 

On 6/10/2020 at 9:31 AM, Catt said:

030: Within 24 hours of applying the etch primer, apply the topcoat finish.

Oops. Wouldn't you know it but once I got it primed (Rustolium self-etch), I'm in my 3rd day of light rain.

What am I risking by not topcoating within 24 hrs.? There was no mention of a 24 hr time limit with the product I used.

[Catt]

6 hours ago, CPM said:

Oops. Wouldn't you know it but once I got it primed (Rustolium self-etch), I'm in my 3rd day of light rain.

What am I risking by not topcoating within 24 hrs.? There was no mention of a 24 hr time limit with the product I used

 

Light sand it & light coat of primer ?

[Salty Cracker]

Will do.