How To: C15a Wire-3 restoration

[Phil Waterman]

Hi Jordan

What ever you do DO NOT use Por 15 on clean smooth steel it will not stick in the long run, it will peal.

Reason I mention this is that your photos show major areas of the frame that look to have good paint which will mean areas of smooth steel.

When I restored my Pattern 12 some years ago I used Por 15 with their metal cleaner and metal etch. Everything is fine on rusted areas or areas which were uniformly roughened with sand blasting or grinding which Por 15 was applied.

But on areas that were smooth because of being new steel or areas where the paint had protected the steel. The Por 15 has pealed off. I discovered this recently when working on the Pattern 12 doing it's nose change. Now I have areas where the bare steel is exposed. In some areas this is nothing to repair in other it is going to be a real pain.

Yes I am still using Por 15 on projects but only in locations that when cleaned and ready for paint actually feel rough to the touch. Which really leaves a problem on finished surfaces like sheet metal, who do you blend areas from Por 15 to regular primer or PORs Tie Coat Primer.

Cheers Phil

[Bob Carriere]

Hi Jordan

Phil is right on new cold rolled sheet metal it willnot adhere properly.

The solution as he pointed out is to roughen the sheet metal surface with small grit sandblasting. The other solution is to use sheet metal with a satin (acid etched) coating from the factory.

I have repaired POR 15 by grinding with a flap disc at 140 grit..... etched....POR two coats and used the tie coat ( all by brush)....... over a year so far no deterioration and not noticable with the two coats of OD.

One question....... are you taking the frame off the axles or blasting the whole assembly as a total unit...?

Cheers

[Jordan Baker]

Thanks for the info and tips guys.

I was just over to see how the frame and cab floor came out from sandblasting. The Por15 should have no trouble at all sticking. The metal feels just like 100 grit sandpaper.

Bob, I left the axels on the frame for now. Once I get it back and painted I will be taking them apart and rebuilding them. I figured I could just do touch ups as needed by hand.

[Phil Waterman]

Hi Guys

I even used Por's Metal Etch or Metal Prep and still had problems with pealing. Jordan you are probably on track with your comment that the prepared steel feels like 100 grit sand paper.

Here is an example of the problem I was having this is a lower fender where new steel has been welded in to replace rusted area.

C60l Cab Work Por 15 Peal.jpg

I really should have ground the steel area with 80 grit disk to give the Por 15 something to mechanically grab on to. Guess the rule with Por 15 is if the metal feels smooth it will not stick.

The other side of the getting paint to stick is as Bob mentions you have to use Por's Tie Coat Primer if you want the top coat to stick.

Cheers Phil

[chris vickery]

Why don't you guys ditch the POR15 and stick with epoxy primer?
The stuff is tough as nails and you have to grind, burn or blast it to get it off of properly prepared surfaces.
Metal should always be roughed up no matter the paint or primer product, unless you are using an etching primer.
Epoxy primer needs to be top coated within 24hrs otherwise it needs to be sanded before paint application, BUT, you can cheat a little bit if you epoxy prime first and top coat with regular primer. Most red oxide type primer can be painted over directly without the need for sanding and can be left for quite some time without worrying about it.
The epoxy primer provides the seal of the base metal while the regular primer acts as the bond for the paint.
You can also have epoxy tinted, I usually go red to simulate factory primer- if the paint gets scratched the primer will still protect the metal and looks original.

[Bob Carriere]

Things to remember. POR is not a paint but a coating. It is basically crazy glue with a pigment. It chemically bonds to whatever it is coating BUT if you can provide a mechanical bond that it is really tough. You can paint POR on a sanded section of sheet metal and bend the sheet metal and the coating will not peel. It will loosen its bond of heat is applied....therefore nto good for engine blocks.

On properly degreased cast axles,
T-case, tranny cases that have been sandblasted the outcome is almost like a ceramic finish.

I had rear axles on axles stands....3 feet tall..... the U shape strap the held the axles in place rubbed off the 3 coats of OD paint and the baby blue Tie coat but did not scratch the POR coating on the axle tubes.

POR cures with humidity in the air.... it starts curing the moment you open the can.... that is why they advise never to paint directly from the can as it will continue to get thicker and spoil very fast even after you seal it.

Eastwood now sells a similar "encapsulator" coating which is solvent based and hardens by evaporation of the solvent.... less toxic than POR fumes whcih can harden in the humid linings of your lungs. I have yet to try it.

The two part epozy primers/paint are also very resistant btu have nto palyed with them yet.

No paint will stick to properly cured POR UNLESS you use a self hetch primer
( which of course POR will sell you) and the tried and true TIE Coat which is a sky blue sandable, thick, self leveling primer polyuethane based.

On new steel...sheet metal.... which has been repaired sanded and polished smooth a light pass with a small sandblaster will take care of the adhesion problems.

IMHO.

[charlie fitton]

I'm enjoying all this paint discussion - it's never been a strong point with me.

POR, Epoxy primer, - Where do you buy this stuff?,

Can you paint outside?, and

inasmuch as safety goes - what special precautions?

f