Author Topic: Advice for priming aluminum enclosures?  (Read 507 times)

ItsGiusto

Advice for priming aluminum enclosures?
« on: February 25, 2021, 11:18:19 AM »
I like to use acrylic paints/sprays on my pedals. For years I've been priming the aluminum enclosures by lightly sanding, rubbing off the sanding dust with mineral spirit paint thinner, then giving it a few light coats of Rust-Oleum Painter's Touch 2X Ultra Cover Flat White Primer. This has worked most of the time, but one time when I was spraying the gloss coat on top in weather that was too cold, the primer coat started to curl up for some reason and ruined the finish.

I'm wondering, since I'm trying to prime aluminum, should I be using a self-etching primer instead of the Painter's Touch? I don't really know what the difference is, but would it still give me a nice white coat, allow me to still brush/spray acrylic on top, and then clear-coat afterward? Would it be better than Painter's Touch in any way? As far as I know Painter's Touch is not self-etching, but it does say that it's suitable for metal.

davent

Re: Advice for priming aluminum enclosures?
« Reply #1 on: February 25, 2021, 12:32:37 PM »
I use the self etching as it's specifically for aluminum and should produce better results then a general purpose kinda works for everything type product and no complaints on the results, just the usual stench of spray can products.
dave
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Ice-9

Re: Advice for priming aluminum enclosures?
« Reply #2 on: February 25, 2021, 12:43:02 PM »
When preparing bare metal for painting it should always get a coat of 'Etch Primer'. This is an acidic primer which bites into the metal. After the etch primer paint with enclosure with the colour(s) you want.
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ItsGiusto

Re: Advice for priming aluminum enclosures?
« Reply #3 on: February 25, 2021, 12:49:12 PM »
Thanks! I can't seem to find the etching primer in white, just gray or green. If I use this gray or green etching undercoat, will it make the white less bright when I spray it on top?

Just to be clear, we're talking about doing first a self-etching non-white primer, then using the white Painter's Touch, then using acrylic paints/sprays on top of that, right? Is that the best way to go?

FWIW, I really haven't had too many problems for years just using the white Painter's Touch on top of bare aluminum, just curious to know if there's something better I should be using. Just that one time when it was cold and curled up.
« Last Edit: February 25, 2021, 12:59:01 PM by ItsGiusto »

ItsGiusto

Re: Advice for priming aluminum enclosures?
« Reply #4 on: February 25, 2021, 12:51:16 PM »
Also, how do I know if a specific primer will work for my top coat and acrylic paints, and won't cause problems? Will this stuff work?
https://www.amazon.com/Krylon-Automotive-Etching-Primer-KA8609007/dp/B087XBFVHJ
Of note, it's green. Will the white top-coat still work over it?
« Last Edit: February 25, 2021, 12:55:15 PM by ItsGiusto »

davent

Re: Advice for priming aluminum enclosures?
« Reply #5 on: February 25, 2021, 01:08:34 PM »
Thanks! I can't seem to find the etching primer in white, just gray or green. If I use this gray or green etching undercoat, will it make the white less bright when I spray it on top?

Just to be clear, we're talking about doing first a self-etching non-white primer, then using the white Painter's Touch, then using acrylic paints/sprays on top of that, right? Is that the best way to go?

FWIW, I really haven't had too many problems for years just using the white Painter's Touch on top of bare aluminum, just curious to know if there's something better I should be using. Just that one time when it was cold and curled up.

After the etching primer I use Zinsser Primer/Sealer Stain Stopper which is white and apply it with an airbrush.


dave
"If you always do what you always did- you always get what you always got." - Unknown
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tonyharker

Re: Advice for priming aluminum enclosures?
« Reply #6 on: February 25, 2021, 01:57:10 PM »
You can also get clear etch primer. Rust-Oleum Automotive 251572 11-Ounce Adhesion Promoter Spray, Clear.  Available from Amazon.

ItsGiusto

Re: Advice for priming aluminum enclosures?
« Reply #7 on: February 25, 2021, 02:26:05 PM »
You can also get clear etch primer. Rust-Oleum Automotive 251572 11-Ounce Adhesion Promoter Spray, Clear.  Available from Amazon.
Oh, cool. Is that an etch primer? I don't see "etch" mentioned anywhere.
Will clear be more compatible with a white top coat?

Also, looks like for the clear one you posted, you're supposed to spray it, then spray the topcoat within 10 mintues of spraying it! That's not what I was expecting. With the krylon green self-etching primer I posted above, I was assuming that I'd spray it, recoat within an hour, then let it dry overnight, at which point I'd spray the painter's touch white top coat on top. Is that right?
« Last Edit: February 25, 2021, 02:36:11 PM by ItsGiusto »

davent

Re: Advice for priming aluminum enclosures?
« Reply #8 on: February 25, 2021, 04:15:18 PM »
You can also get clear etch primer. Rust-Oleum Automotive 251572 11-Ounce Adhesion Promoter Spray, Clear.  Available from Amazon.
Oh, cool. Is that an etch primer? I don't see "etch" mentioned anywhere.
Will clear be more compatible with a white top coat?

Also, looks like for the clear one you posted, you're supposed to spray it, then spray the topcoat within 10 mintues of spraying it! That's not what I was expecting. With the krylon green self-etching primer I posted above, I was assuming that I'd spray it, recoat within an hour, then let it dry overnight, at which point I'd spray the painter's touch white top coat on top. Is that right?

Rustoleum calls it an "Adhesion Promoter" for  bonding " topcoats to vinyl, plastic, fiberglass and more", "helps paints adhere to polyolefin surfaces such as automotive plastics, vinyl, trim, bumpers, fiberglass and more", nothing about aluminum or self etching.

https://www.rustoleum.com/product-catalog/consumer-brands/auto/primers/adhesion-promoter

I spent some time the other day looking for clear self etching primer and failed.
dave
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amz-fx

Re: Advice for priming aluminum enclosures?
« Reply #9 on: February 25, 2021, 04:21:55 PM »
I also use a self-etching primer, usually Rustoleum or Krylon. Easy to find at an auto parts store, or Lowes Home Center.  Works great, but you still need to sand the box to promote the best adhesion. Then wipe off the sanding dust with a little alcohol on a paper towel, and paint when dry.

regards, Jack

Radical CJ

Re: Advice for priming aluminum enclosures?
« Reply #10 on: February 26, 2021, 07:51:30 AM »
I use the gray spray can stuff and it works very well. Putting a coat of a lighter colour/white on top is fairly easy. Just be extremly patiant with lots of thin layers to avoid runs. I've tried going straight to white with an enamel paint and results were extremely bad.

ItsGiusto

Re: Advice for priming aluminum enclosures?
« Reply #11 on: February 26, 2021, 12:23:51 PM »
I use the gray spray can stuff and it works very well. Putting a coat of a lighter colour/white on top is fairly easy. Just be extremly patiant with lots of thin layers to avoid runs. I've tried going straight to white with an enamel paint and results were extremely bad.
Do you have advice on how to transition from the self-etching gray primer to a top coat? Do you let it dry for 24 hours before putting the top coat on?

davent

Re: Advice for priming aluminum enclosures?
« Reply #12 on: February 26, 2021, 01:09:36 PM »
I use the gray spray can stuff and it works very well. Putting a coat of a lighter colour/white on top is fairly easy. Just be extremly patiant with lots of thin layers to avoid runs. I've tried going straight to white with an enamel paint and results were extremely bad.
Do you have advice on how to transition from the self-etching gray primer to a top coat? Do you let it dry for 24 hours before putting the top coat on?

The can of paint will give you times, dry to touch, dry to handle, dry to top coat, dry to dry sand, dry to wet sand... Dry time to sand is far longer than dry time to top coat. Dry time to top coat is 30 minutes ideal then says depending on conditions can take longer. This is a can of Rustoleum Self Etch Primer.

A couple of keys to finishing is don't be in a hurry and don't apply heavy.
dave
"If you always do what you always did- you always get what you always got." - Unknown
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ItsGiusto

Re: Advice for priming aluminum enclosures?
« Reply #13 on: February 26, 2021, 01:37:21 PM »
I use the gray spray can stuff and it works very well. Putting a coat of a lighter colour/white on top is fairly easy. Just be extremly patiant with lots of thin layers to avoid runs. I've tried going straight to white with an enamel paint and results were extremely bad.
Do you have advice on how to transition from the self-etching gray primer to a top coat? Do you let it dry for 24 hours before putting the top coat on?

The can of paint will give you times, dry to touch, dry to handle, dry to top coat, dry to dry sand, dry to wet sand... Dry time to sand is far longer than dry time to top coat. Dry time to top coat is 30 minutes ideal then says depending on conditions can take longer. This is a can of Rustoleum Self Etch Primer.

A couple of keys to finishing is don't be in a hurry and don't apply heavy.
dave
Thanks! Are there ever any limitations? How do you know a specific primer will be compatible with a specific top coat, clear coat, type of paint, etc?

davent

Re: Advice for priming aluminum enclosures?
« Reply #14 on: February 26, 2021, 02:06:07 PM »
The only spray can products i used were the etching primer and rubberized rocker panel paints but limits, sometimes a window will be presented, recoat within a certain time, the can will say.

Stick with one company's products, better chance they'll be compatible, trail and error tells you lots, sometimes it's months down the road before things fall apart.

What worked for me was any brand of etching primer i tried, after that heavy air brush use - the Zinnser primer sealer, high solids & good build sands real nice, paints and mediums from Golden,  Acrylic artists products, clearcoat with waterbourne lacquers using airbrushes and again here brand didn't matter but it was always ones recommended for instrument finishing, clear not milky like poly's that i tried and no yellowing.

Lengthy process i had time, I'd do a number of enclosures with the etch primer and Zinsser when i could do the etch primer outside in the summer so i had prepped enclosure to use in the winter.
dave
"If you always do what you always did- you always get what you always got." - Unknown
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bluebunny

Re: Advice for priming aluminum enclosures?
« Reply #15 on: February 27, 2021, 06:29:05 AM »
How do you know a specific primer will be compatible with a specific top coat, clear coat, type of paint, etc?

The primer, paint and clear-coat I use are all intended for use on cars and all come from the same supplier: they're designed to work together.  You might try to take this approach?  Things have gone pear-shaped for me when I've gone off-piste with unknown chemistry combinations (or too fast/too thick...  :icon_rolleyes:) - no longer a problem, since I stick with what works.
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anotherjim

Re: Advice for priming aluminum enclosures?
« Reply #16 on: February 27, 2021, 07:39:38 AM »
In the UK, Halfords is one popular brand that sells compatible automotive finishes and that includes etching primer. And, unlike a lot of retailers here, they seem to understand the need to stock more cans of primer on the shelves than they do colours. Makes my teeth grind when the primer is always out of stock.
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bluebunny

Re: Advice for priming aluminum enclosures?
« Reply #17 on: February 27, 2021, 09:37:53 AM »
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