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Consensus on primer on aluminum

KLOU

KLOU

I'm New Here
I’m certain this has been asked and answered numerous times on here but I could not find the right thread for the answer. I am all squared away on the fiberglass parts with great results with final paint. I am DIY and finally researching the prep for aluminum before paint.
What are most using as primer and prep prior to priming?
Thank you everyone for the advice and expertise.
Cheers!
 
KLOU said:
What are most using as primer and prep prior to priming?
Click to expand...

Most of the people that voted in this poll from last summer use a rattle can for primer.

Poll: Which primer did you use?

As a new builder, I've spent hours researching priming. The one thing I wasn't able to find was a poll on which primers folks here are using. Just curious which primer is the most popular. If you primed, which did you choose?
vansairforce.net vansairforce.net
 
Welcome to the war.., but honestly old school zinc chromate is not the way to go. I won't lead you down the path of brand names, but in today's world we have marvelous epoxy and urethane primers that will fit the bill. Don't prime external aluminum surfaces until you are ready for final paint coat. Primer/topcoat will bind together with certain systems by design. I used what we term fluid resistant primer for all my internal work, that resists anything you dump on it. Its green, but is not a high chromate primer. Externally, I used a popular PPG topcoat and it's recommended compatible primer. I make my living in heavy jet overhaul for the last 44 years, so I'm around alot of paintwork, which doesn't make me an expert, but certainly exposes me to the old and the new paint systems...I DIY painted my RV-4 with "surplus" products that expired..I was lucky, paint is very expensive!
 
Primer before paint, use the recommended products that the top coat manufacturer recommends. Most paint manufacturers want you using there products and processes from the surface out.
 
If you decide to prime, it is best to alodine the aluminum surface to get the best adhesion of primer. It is somewhat labor intensive and some people skip it and still got good result. However, the labor is miniscule compared to prepping the airplane for priming and painting.
 
I assume we're speaking of exterior finish paint.

What Bill and Gary said. Treat it as a system, and follow the tech sheets from the manufacturer.

There is no one best product or combination. To illustrate, here is the response from PPG when I asked about aluminum finishing systems, circa 2009. Even limiting to just the Deltron product line, there were still multiple choices. "A few things to keep in mind" illustrates the wisdom of sticking to the tech sheets, i.e. no product mix and match:

Thank you for your interest in PPG Refinish products. Aluminum may be refinished by one of the following Deltron combinations:

1. Etch primer DX1791, DPLF Epoxy, DBC, Deltron Clearcoat of choice
2. Etch primer DX1791, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
3. Etch primer DPX171, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
4. DX533, DX503, DPLF Epoxy, DBC, Deltron Clearcoat of choice
5. DX533, DX503, DPLF Epoxy, DPS3055, DAS3025, DBC, Deltron Clearcoat of choice
6. DPLF Epoxy(2 coats) DPS3055, DBC, Deltron Clearcoat of choice

These are just some of the combinations. All told there are probably another 10 more. A lot would depend on whether or not sanding is necessary (DPS3055, K36, K38 all require sanding...). The most common combination involves DPLF Epoxy somewhere in the mix. Options 1 and 4 are the most common. The rest is up to you.

A few things to keep in mind:
1. You CAN NOT apply DPLF Epoxy over DPX171 Etch primer. The only Etch products that may go under DPLF are the DX1791 Etch primer, and the DX503 Aluminum Conditioner.
2 If you decide to use the Metal Treatments (DX533 & DX503), you can not use any other kind of Etch primer as well (DX1791, DPX171)
3. DCC Concept Acrylic Urethane Single Stage may be used in place of DBC basecoat if you decide not to clearcoat.

I elected #1, with mechanical etch rather than etch primer, and DCU 2021 clear, which cuts and buffs well. Primer, DBC and clear all go on in a short time window, a tech sheet requirement. Chipping it has required visiting someplace fun with big rocks.

P8050005.JPG
 
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I think a lot of responses aren’t realizing that the OP is asking about the exterior priming, not the interior ribs ect.. I would think it’s best to find out what primer plays best with the paint you intend on using.
 
"Consensus on primer" is an oxymoron. But if you're asking about prep for exterior paint, ask your paint supplier. Most brands have multiple primers, with different advantages, and you can discuss your project with them.
 
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