Bare metal suspension parts - THIS THREAD IS OFFICALLY OVER

[750-h2]

I once sand blasted a metal bracket. Bracket looked perfect afterward with zero rust anywhere. I then clear coated it with POR15 clear. Bracket looked great, however about a year later you could start seeing a very light rusty colour under the clear. The POR15 still looked perfect with zero damage but somehow the metal beneath it was starting to oxidize?? Ever since then I have been leery about clearing directly over sand blasted or bead blasted metal. Makes no sense I know, but it happened.

[HEMICUDA]

I once sand blasted a metal bracket. Bracket looked perfect afterward with zero rust anywhere. I then clear coated it with POR15 clear. Bracket looked great, however about a year later you could start seeing a very light rusty colour under the clear. The POR15 still looked perfect with zero damage but somehow the metal beneath it was starting to oxidize?? Ever since then I have been leery about clearing directly over sand blasted or bead blasted metal. Makes no sense I know, but it happened.

I would half to say the issue is with the POR15.  The only way I can imagine the part rusting is the POR15 is pouris and letting moisture get to the part.  If you encapsulate rust from any air or moisture, it will not rust.  I've only ever used the black POR15 years ago, that formula held up big time, never used the clear.

[RUNCHARGER]

I usually heat the metal after blasting to make sure it is dry as well. Lightly of course.

[JS29]

I usually heat the metal after blasting to make sure it is dry as well. Lightly of course.

humidity in the air can cause issues, an untreated piece of bare metal won't rust as fast as blasted metal.   

[Shane Kelley]

I once sand blasted a metal bracket. Bracket looked perfect afterward with zero rust anywhere. I then clear coated it with POR15 clear. Bracket looked great, however about a year later you could start seeing a very light rusty colour under the clear. The POR15 still looked perfect with zero damage but somehow the metal beneath it was starting to oxidize?? Ever since then I have been leery about clearing directly over sand blasted or bead blasted metal. Makes no sense I know, but it happened.

Something that comes to mind. Maybe some very minor moisture in the air supply for blasting. You might not see it but it's probably there. If you looked under a microscope you might have seen it on the metal but unable with the naked eye. That stuff will develop with time under the paint surface unless you keep it climate and humidity controlled. Temp changes that make steel sweat really aggravate the problem.   

[JS29]

Change in temperature can make metal condensate! the higher the dew point the worse it gets. One time i blasted a bracket, etch-primed it went back and found rust on it. after. I left the fan running and ether the air  from the shop got damp, or the compresser air, or the air in between caused it. When i sandblast on a vehicle now i etch it as soon as i am done. I worry about the sand in the primer later!

[HEMICUDA]

Detailing some parts on a blue 4 speed AAR Cuda we're restoring, this is the 3rd member right out of the blast cabinet.

[HEMICUDA]

This is showing the metal staining, it looks like "flash" rust, it's not.  The solution I have in a tub is, at lease, 10 years old, that's part of the residue you see here.  I have a couple more gallons coming in.

[HEMICUDA]

This is what the finished part looks like after polishing.  Needs a little bit more in the nooks and crannies, not much.  After blasting, the metal staining takes 10 seconds and the polishing around 10 minutes give or take.

Once I get the new powder coating gun today, I will be coating the part with a thin coat of flat clear.

[JS29]

What is metal staining? 

[HEMICUDA]

 "Cold" bluing is generally a selenium dioxide based compound that colours steel black, or more often a very dark grey.  Any shop that can do "real" judged OE cars uses this process regularly.  You've seen it on OE judged cars and didn't realize it.

You can never duplicate the patina of true bare metal with any type of paint.  I want to be able to offer the OE bare metal with out the issues inherent with bare metal parts.

[RUNCHARGER]

That looks really good.

[HEMICUDA]

I understand what I'm showing here isn't for every one, for me, I cringe when I see originally bare metal parts painted on "so called" restored cars.  In addition, I don't like the user unfriendliness of bare metal parts, I'm going to get my cake and eat it to. 

[Shane Kelley]

While not going as extensive with the discoloration here and there I'm pretty happy with the cast iron powder coat. In person it's hard to tell it's not raw.

[HEMICUDA]

Looks great Shane, like I said before, I want bare metal parts that will last as long as your cast colored powder coating.  Let's try not to confuse what this thread is about, bare metal parts.  Painting or colored powder coating is easy to do.  What you're doing is exactly the same as what I'm showing here, powder coating over bare cast or steel parts except your powder has a color and mine does not.

Problem with yours is, it looks way to good.