Best treatment for new parts? Bare blasted parts?

[baxsie]

I am trying to decide how to treat the undersides of the used fenders and the new running boards.

The fenders are rusty now, and so will be blasted down to bare metal.

The new running boards are painted, I am not sure if that is a "cheap" coating intended to only keep it from rusting during shipping or if it is a nice powder coat. We can blast those to bare metal also if that is the way to go.

So the first question is: "Should I remove the black primer on the new parts or scuff that and paint over it?"

Once they are bare, I can think of two basic approaches:

1) have the body shop shoot them with primer and finish paint underneath, then apply undercoat to the finish paint.

--- OR ---

2) Use the 3-step KBS rust seal on the bare, blasted metal underneath, then apply undercoat. Later the body shop would primer and paint the tops as normal.

With either of these approaches, I plan to have the "gravel impact area" at the lower rear section or each fender (~1 foot or so) shot with the "Rhino Hide" truck bed coating. I did not like seeing my beautiful paint ruined by a gravel impact from inside the fender.

I am open to suggestions on the best approach to coat and protect the undersides of the fenders and running boarts.

[skills@eurocarsplus]

blast anything you want to last, and get it into a coat of epoxy
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[Bobnotch]

[baxsie]

Can you post a link to some of the "epoxy" I should use?

Does it just go right over the bare, blasted metal? Or is there some kind of primer under the epoxy?

I had assumed that the first thing over the bare metal should be the POR-15 or the KBS Rust Seal. Am I missing something there?

[FergU]

When they say "epoxy", they are referring to epoxy (2K) primer.
_________________
1962 Type 1
1963 Type 14 - Karmann Ghia "Sadie" (Restoration progress - http://vwsexysadie.wordpress.com)
1972 Type 3 - Squareback "Joseph" (Restoration Progress - http://jpdproject.wordpress.com/)

[baxsie]

OK, so would a rattle can aerosol like this:
RUST-OLEUM Aerosol 2K Epoxy Primer, Gray, 13.2 Oz
or this:
Spray Max 2K Epoxy Rust Cure Primer - 3680032
work? Or am I looking for something SERIOUS like this:
GLASURIT 801-704 CV EPOXY PRIMER FILLER CHROMATE FREE

I am getting a real disconnect between all the talk about POR-15/KBS RustSeal and these Epoxy primers. These primers sound like what you would put on the upper (finish) side of the fenders--which I will let my paint shop do.

What I'm looking for is the product and procedure for UNDER the fenders and running boards to protect from the road, gravel, etc.

Can someone help reconcile where the POR-15 type product should be used compared to the Epoxy 2K product?

Thanks in advance for your help.

[ccpalmer]

I would only use POR15 if there was a lot of rust/pitting. If it is clean metal 2K epoxy is the way to go.

I had my bumpers sandblasted and then put 2 coats of DP90 epoxy on them. Insides of the bumpers are showing rust again after 5 years..

If you aren't worried about color try Macropoxy - black super high-build epoxy from SW
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'71 Westy

[Bobnotch]

[baxsie]

I was thinking that I was becoming clear on this, but then I see:

[BUSBOSS]

Don't use POR15 on newly blasted materials. It will work but the best results are on material that is slightly rusted.

Rattle can rustoleum will work fine for your application based upon your description. Make sure you put the most effort, time and care into the prep of the surface.
_________________
All the redemption I can offer, girl, is beneath this dirty hood
1976 Westfalia
1970 Karmann Ghia Convertible (sold - but not forgotten)

[ccpalmer]

[beetlenut]

[baxsie]

There really seem to be a lot of ways to go here.

I went by my local NAPA Automotive Finishes store and talked at length to the very helpful and knowledgeable person there.

The big take-away I got from him is that if I really want long life, I need a "DTM" ( Direct To Metal ) primer. These primers should have the zinc (or other metal) in them that will retard the rust if the outer finish is penetrated.

He sold POR-15, but warned that if the POR-15 is punctured (by sharp flying gravel) that the tiny exposed metal area would then start growing rust. He really stressed that the important thing was to have zinc metal in the primer.

Within the DTM primers there are sandable/no-sand one step/two step and cheap/expensive.

What we decided would probably be the best product for me from NAPA would be the Martin Senour 5227 DTM Epoxy, which is a 2 component, one step process:

http://www.martinsenour-autopaint.com/media/pds/english/MA4702.pdf
http://www.paintdocs.com/msds/PdfDisplay.jsp?docId=43527625
http://www.paintdocs.com/msds/PdfDisplay.jsp?docId=43527624

I'm no expert, but I do see zinc listed on these data sheets, which backs up his claims.

Another possible solution was a two step, using an etching primer then a two component epoxy on top of that. Again he stressed that the important thing was to make sure the etching primer has the zinc in it.

On a separate topic, I mentioned that I wanted to have "Rhino Hyde" shot under the fenders at the gravel impact area. He mentioned that their NAPA store sells a kit for that called "Raptor". It looks like the same thing is here:

http://www.tptools.com/p/2600,186_U-Pol-Raptor-Truck-Bed-Liner-Kit.html
http://www.u-pol.com/documents/datasheets/tds/RLB-TDS-US.pdf

I hope to stop by the PPG store later and ask them the same questions, and also ask the body shop that do the finish painting.

[baxsie]

I contacted a local metal plating shop here in Spokane.

He says he can do "zinc chromate" on the bare blasted parts.

My understanding is that the finish will look like this:

ref: http://www.yellowzincplating.com/FAQ/yellow_zinc_electroplating_information.htm

My plan is to bead blast the four fenders and two running boards and get them dipped.

At this point, my big question is if the automotive finishes will bond to the zinc chromate. At least two source says that paint can be applied successfully over the zinc:
http://www.infinitechfinishing.com/Articles/Article7.htm
http://www.thesamba.com/vw/forum/viewtopic.php?t=529603

[panicman]

Rustoleum Rusty Metal primer comes in a brushable can. I refinished my fender under-sides by sanding and wire brushing, using napa rust treatment, wait two days, then brush the Rusty Metal primer on. If you have your hardware store shake the can in the machine, it goes on very smooth. I let it harden for a few days, then used SEM satin black chip gaurd (which is paintable if you want to) on top of that (2 to 3 coats). It also goes on smooth, but not as smooth as paint, more like a modern car wheel-well. The finished look is good, and I think it will be quite durable. It is not rubbery or tarry, and running your hand over it feels like almost a plastic liner. I would do it again, and may use that SEM product on the undersides of my running boards as well.

Another plus is that if a big rock DOES happen to cause a big scrape or chip, I can clean up the damage area and re-spray that chip gaurd on.

[tspot100]

por 15 works GREAT on new blasted metal to protect and prevent rust. follow application on can to the letter and you will not be disappointed. i have por'd many, many, mnay new parts with very long lasting protection. starters, master cylinders, body panels etc... it's pricey but fantastic. only peels if you do not follow instructions and degrease well. acid etching needed if not blasted

[baxsie]

I did some adhesion tests for RustSeal (POR-15 competitor) over here:

http://www.thesamba.com/vw/forum/viewtopic.php?t=5...p;start=25

My conclusions:

* Using a wire brush only, with or without etch does not get a good bond.
* Bead blasting without an etch does not get a good bond.
* We only saw good bonds on the bead blasted, etched samples.

2K epoxy sticks with no etch, even on the zinc chromate.
_________________
1975 LaGrande Super Beetle Build Log / Farm boy hinge pin puller / Farm Boy Chassis Rotisserie
"I'm not getting older, I'm getting bitter."

[ccpalmer]

[ccpalmer]

[baxsie]