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Not Sure I Even Want To Powder Coat?

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Old 01-04-2015, 11:17 PM   #1
Crumpler
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Default Not Sure I Even Want To Powder Coat? Polished Metal Intake

I am tired looking at my shabby looking intake.
I was going to do some work on the top end this winter.
Currently the intake has some residual stock powder coat which is flaking off and a little rattle can rampage from a few years ago, which was high heat paint but still discolored to a ugly brown hue.

I have some credible leads on powder coating around town, and I was going to move on that. But my impression is that even quality powder coating won't last as long as I would want it to (i.e., forever).

I was talking to a client who recommended just going down to metal, buff to shine, and then use an aluminum product called Sharkskin.

Has anyone done this and what are the cons of bypassing a powder coat altogether.
My bonus is that I am an raw aluminum freak to begin with, and the look of a raw metal pipe organ turns me on. See pic below for teaser.

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Last edited by Crumpler; 01-31-2015 at 05:37 PM.
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Old 01-04-2015, 11:34 PM   #2
bureau13
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There are a couple threads about how the metal is some alloy, not really straight aluminum...given that I've never seen one in polished form like you describe makes me wonder if it's even possible to get it looking right like that? If you can, it would be sharp...
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Old 01-04-2015, 11:41 PM   #3
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pretty obvious it is 17 degrees in St Louis and cabin fever is already showing up
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Old 01-04-2015, 11:47 PM   #4
Rob Edwards
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There's some discussion of electropolishing in this older thread RE: polishing 16V intake spiders.

https://rennlist.com/forums/928-foru...-a-spider.html

I think a highly polished bare metal S3 intake would look great, would be a ton of work, tho- there's what, 100 square feet of surface area?
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Old 01-05-2015, 12:46 AM   #5
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The S3 intake is magnesium and therefor will blacken quickly.

If you polish, have it clearcoated to maintain the shine.
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Old 01-05-2015, 12:49 AM   #6
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Who's said that Powder Coating isn't going to last?
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Old 01-05-2015, 12:55 PM   #7
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Thanks for the feedback and links you guys.

Yea, Mr. Bailey is right, I need something to do, LOL, it's either this or whittling some albino snakes out of tree branches...

FYI, the product recommended by the client was Shak-Hide, not Shark-Skin, my bad.
I'm glad I asked, I did not know I was dealing with an alloy.

Sean, what do you see out there in terms of powder coat jobs holding up?
Is it uncommon that a "good" powder coat will flake in five to ten years.
I guess I only have access to anectdotal information, at some point I heard that it really matters who does it in regards to how long the job will last. Then I had the impression that any coat job will flake eventually.
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Old 01-05-2015, 09:01 PM   #8
Bertrand Daoust
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If well prepared, a powder coat job will last many years.
I had mine done five years ago and it still looks like the first day.
No flaking, no color change at all.

Also, powder coating is a lot more resistant to scratches.
A very good thing when re-installing both the intake and valve covers and working around in the future.

If you go with powder coating, you absolutely need to make 100% sure that everything is perfectly clean inside every parts before re-installation.

Like Colin said, if you polish you'll need to clear coat.
Unless you want to do it regularly. Not ideal!
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Old 01-05-2015, 09:55 PM   #9
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If stripped and beaded and left to oxidize, how black do they get? I often wondered about just leaving them unfinished.
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Old 01-05-2015, 11:04 PM   #10
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You need to meet Ben in Austin. He has powder coated many in the DFW area. He did mine this fall and I'm very pleased with the results. He also did Rodgers' and The Charlie Car. Sean has his contact info. Good luck!
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Old 01-06-2015, 12:18 AM   #11
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Here is what an S4 intake looks like oxidized. I did sand a few bits and you can see the difference in these areas.
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Old 01-06-2015, 12:44 PM   #12
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I don't think the factory finishes were powdercoat - just paint - certainly true for the late intakes. These don't hold up well in color fastness or durability in the long haul. So don't use the long term effects on the stock finishes as a gauge...

I'd expect powdercoat to be better than this and have not heard of issues except where the initial quality was suspect (e.g. surface prep & sealing surface protection).

My crinkle black powdercoat looks like new - I fully expect it to stay that way for a good long time.

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Old 01-06-2015, 02:50 PM   #13
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I rattle can my S4. Duplicolor ceramic. Looks ok. A LOT better than the totally trashed stock finish. It is susceptible to nicks and chips from working on it, and down by the where the manifold meets the motor I have a little coming up. I suspect that is imperfect prep rather than heat. It might good idea to bake it prior to painting as I think the alloy soaks up some oil and all the scrubbing and sanding in the world will not get the oil out. Also a catalyzed clear coat would probably toughen it up. You can get a catalyzed rattle can clear coat from paintscratch.com
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Old 01-06-2015, 03:17 PM   #14
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Magnesium alloy is a chemically very reactive metal.

From the microsecond it's produced it reacts with atmospheric oxygen to produce magnesium oxide - a white powder - that will prevent anything from adhereing to to the surface of the casting.

For this reason the surface must be chemically passivated - ie a chemical must be applied to the surface to react with and specifically bind with the Magnesuim atoms to prevent them from reacting with oxygen.

This is the dark gray layer seen under the OEM paint as it flakes off, and is the surface passivation layer laid down by the foundry supplying the castings to Porsche.

Should you want to remove this to the bare and very shiny metal it will be a sight to behold, but you must have a means of immediately clear coating the mag alloy as soonn as that coating is removed.

Best of luck, but the end result should be well worth the effort.

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Old 01-06-2015, 08:02 PM   #15
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Dave,

Look into Tagnite coating for magnesium alloys. Aerospace/ Auto industry uses it.

Then paint over it with your leftover black urethane.

The Tagnite which is a lite grey color, then paint the intake black after taping off the PORSCHE.

Would be unique and fit your ride aesthetic imo.

Tagnite will last indefinitely over magnesium alloys, as a substrate for a quality automotive paint it's a win.

Best,

Matt
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