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Old 04-23-2020, 06:07 PM
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Is there a trick to painting aluminum?

Kind of an open question because I don't know where to start. I want to paint my radiator shroud to match the car. It's aluminum. I'm reading all sorts of stuff online about so many different types of primer. What do I need to shoot on it to make sure everything sticks especially given that it will get radiator hot.

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Old 04-23-2020, 08:38 PM
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Use an etching primer, if you want a really tough primer use Zinc Chromate, it is also an etching primer. Of course you need to scuff up the aluminum first, it gets a coating after setting for a while.
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Old 04-24-2020, 04:37 AM
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Like MGK said, etching primer or zinc chromate. I always use etching primer. I tried epoxy primer but still had peeling issues after a fashion.
Prep is key as well. Use a coarse ScotchBrite pad to scrub the aluminum before paint and keep it clean. Wipe it down well with a good degreaser (PrepSol or Pre-Kleeno) right before spraying.
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Old 04-24-2020, 04:50 AM
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I can't think of the manufacturer right now, Oh, it hit me. Cold Case radiators in Hatfield, PA. They sell spray cans of black radiator paint. You really don't want to have too much paint on it unless your radiator is oversized. The thicker the layers of paint, the less it will cool. They tell you to paint the top reservoir however you like, but use as little as possible on the tubes and fins. Some people like the rad painted so you don't see it behind the grill.
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Old 04-24-2020, 06:44 AM
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Quote:
Originally Posted by Gorf View Post
Kind of an open question because I don't know where to start. I want to paint my radiator shroud to match the car. It's aluminum. I'm reading all sorts of stuff online about so many different types of primer. What do I need to shoot on it to make sure everything sticks especially given that it will get radiator hot.
He is painting the shroud, not the radiator.
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Old 04-24-2020, 06:54 AM
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I painted the fins on the front side of my radiator to make it black out behind grille, just the front side. I used hi temp flat black . Sprayed at 45* angle from right and left. Cross flow would have to spray from top and bottom. Fogged it on, use as little as possible. Black paint conducts heat better than any color.
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Old 04-24-2020, 07:14 AM
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Quote:
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He is painting the shroud, not the radiator.

I shouldn't post before my second cup of coffee.
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Old 04-24-2020, 01:18 PM
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My procedure for aluminum is as follows: I clean the aluminum with scotch brite pads and "Aluma prep, as soon as it is thoroughly cleaned I apply alodine liberally and dry. I have used zinc chromate over the alodine and gone from there with epoxy primer and finally a top coat. I have never had a failure following that procedure. I have had spots when I forgot and touched the aluminum with bare fingers but as for peeling never happened and I painted a couple of old airplanes and I see one regularly and it still looks good..
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Old 05-04-2020, 04:44 PM
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Alodine provides a paint ready surface. No need to further prime, (but some folks do)

Now what I do is clean with w&g remover, then water sand with red scotchbrite, and prime with epoxy.
Or on large areas such as a whole vehicle, scotchbrite and water with alcalyne soap, then scotchbrite some more with clean running water as rinse, until the water "sheets" and does not bead up. Then a coat of EAP-12,
then when dry, prime or paint as usual. EAP-12 or-9 is a conversion coat, much better than alodine, and does not require to be washed off prior to topcoat.
But for a radiator shell, just the scotchbrite, and clean soapy water, then rinse and dry, will work just fine, and topcoat with a decent epoxy primer, and paint.
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