Opinions on POR 15, zinc powdercoat or epoxy as a primer.

[fly-s30]

Hey there, I am restarting a project after some considerable delay, and the first thing on the agenda is body work.
Most rust has been removed and repaired, though existing damage to quarter needs to be looked at among others.
Sandblasting is the treatment Im going for to remove paint and surface rust that has inevitably come up, but currently still unsure as to what post-blast primer is going to go on.
Options are:
A: POR-15 
Local paint shop recommends it...and luckily enough stocks it on the shelf  Looks good promising, but I personally have no experience with it. 

B:Powder coating 
A place around the corner that does zinc powdering on a whole shell in grey, black or red. Its sprayed in the oven, then baked. Supposedly gives a very hard coat and penetrates the steel and is a good preventative to rust. Almost like what manufacturers do these days.

C: Epoxy Primer
Ol' trusty, and seems a favourite for those in the industry, so im told.


Questions for those in the know:
Before blasting, is it worth while doing rust repairs, and metal finishing? Ideally my preference would be to smooth body by hand rather than fill, albeit within reason. 

If using POR 15 system for the underbody area, does it get used in combination with other systems? What, if any, are the compatibility issues with this? Can it be applied to the whole shell?? Touch ups? Can it be welded over? Opinions on the product? What are its limitations?

Powder coating zinc? With this treatment was told repairs are to be done as per norm, then once welded, just touch up with zinc pressure pack.

Epoxy. Once set does it get in the way of the bonding of metal wiping? Is it weld through or are there other products for that?
Is it a reliable rust barrier/preventative? 
If not, what can be applied over as a preventative for areas such as rockers, wheel wells, gutters, cowls, window frames? etc.
And in what sequence ie: blast, primer, protection, topcoat, more protection?

Any advice is appreciated, as this is not my my area of expertise. 
Any alternatives not mentioned? Any procedures that must be followed or things to avoid? 


Thanks in advance.

[Kurbycar32]

You should media blast, do metal work, then spot blast if necessary.  Doing metal work on a rusty surface is never fun.

 

I have been using "Rust Bullet" for a few years and its essentially the same as POR15 so I can comment on that

 

First its a fantastic product and lots of car guys swear by it.  it can be applied via brush or thinned down and sprayed out of a gun like regular paint.  My experience has been with brush on applications, it goes on thick and has a texture that's divited like a golf ball.  Its designed to be applied directly to rust and then painted over, though I try and clean any visible rust before using it.  Hypothetically if i had an empty shell on a rotisserie i would apply POR15 or rust bullet to the entire undercarriage and interior after media blasting then paint then apply undercoating.  I would not coat any of the body, I believe its texture might interfere with the quality of the paint job.  Epoxy primer would be more appropriate for the body, paint shops have experience with it and its been done thousands of times before.   The worst part of the whole process is that you need to be really careful not to fill any of your screw holes with POR or you will need to re-tap every hole you fill.  You do not want to weld over it just as if you were dealing with a painted surface, however you can remove the coating, weld, and then brush on touch up material without any setup or special process.

 

Powder coating is awesome because the process actually bonds material to the metal and goes on really smooth.  Its fantastic and affordable for small parts because they fit inside an oven, baking to around 400 degrees is a required part of the process .  When doing a large project like a whole undercarriage the baking part gets difficult and therefore cost prohibitive.  I haven't seen a shop able to spray an entire chassis in an oven so I'm skeptical about this being affordable.

[cockerstar]

A word of caution with POR products:

 

If you're using their system, use their system and not just the paint. There's a reason why they make cleaner and etch to go on before the paint.

Also, if you plan to top-coat it you'll need to use their primer before applying anything over it.

 

 

If you're looking into the powder coating option, inquire about leaded seams, as there are a couple on our cars. 

[fly-s30]

Huntin around and found there is a place round the corner with a big enough booth for cars our size he charges AUD$450 for the zinc coating.

Almost as expensive as a POR kit, with tiecoat AND epoxy down our neck of the woods...

The product he uses is either dulux zincalume or Akzonobel zinc.

Im working in the shipping industry and Dulux, Akzo and International paints are whats used so they are proven products.

The bloke says he can coat over the lead no problem, but it will probably come out with blasting anyway.

I wonder how effective the zinc would be at keeping rust at bay in the future?

 

Thanks for you help fellas.

[280z4me2]

Por 15 is great for heavy rusted areas and is damn near bullet proof. Zero rust is a great after blast coating before undercoat.

Being that the shop will not get every scale of rust while blasting. My vote would be por 15 then topcoat it with there tie coat priimer. Easier to sand then por once cured and can be topcoated.

[280z4me2]

Por 15 is great for heavy rusted areas and is damn near bullet proof. Zero rust is a great after blast coating before undercoat.

Being that the shop will not get every scale of rust while blasting. My vote would be por 15 then topcoat it with there tie coat priimer. Easier to sand then por once cured and can be topcoated.

[280z4me2]

Por 15 is great for heavy rusted areas and is damn near bullet proof. Zero rust is a great after blast coating before undercoat.

Being that the shop will not get every scale of rust while blasting. My vote would be por 15 then topcoat it with there tie coat priimer. Easier to sand then por once cured and can be topcoated.

[SlowRob]

The undercarriage of my Z is treated with the POR15 deal, and while it hasn't seen a ton of miles, it looks as new as when it was applied 10 years ago.  Be sure to use all of the recommended POR products for prep, etc, and it should hold up well.  And I'll second the comment re:filled holes.  In hindsight, I'd fill all bolt holes with clay or vaseline first.

[fly-s30]

Por 15 is great for heavy rusted areas and is damn near bullet proof. Zero rust is a great after blast coating before undercoat.

Being that the shop will not get every scale of rust while blasting. My vote would be por 15 then topcoat it with there tie coat priimer. Easier to sand then por once cured and can be topcoated.

You raise a good point regarding the missed rust scale; cant really get past that unless the car is acid dipped, then run through a zinc bath...to be sure, to be sure 

Internal areas are a worry, such as pillars, forward lower sills and other boxed in structures.

That begs another question; any recommendations/ opinions on protecting those areas and what is the procedure? Keeping in mind these areas are subject to condensation, water immersion and the sort.

[280z4me2]

Eastwood inner frame paint is probably your only option unless the parts are removed. It works pretty good to slow down rust.

[johnc]

If you're completely stripping the car via media blasting you don't need to use a rust encapsualtor or converter liker POR15.  Physically remove ALL the rust and patch all the rusty panels.  Do all of the body work and when its ready for paint use a high zinc etching primer.  Make sure the entire body is sprayed with that stuff and cut small spray holes in the frame rails and other body cavity area to spray inside. After everythign dries plug those holes withe rubber body plugs.

 

Do it right.  Make sure there is NOT rust anywhere on the car before painting.