POR 15 issues Need Help

[6600DURAMAX]

Doing frame off on the K5 - everything besides the axles is getting powdercoated - didn't want to do the axle because I didn't want to pull the gear set out ( have no clue how to reset up).

Anyhow - full axle tear down so decided to paint with POR 15 - cleaned everything with their degreaser/clean - then metal prepped

coated first coat with POR 15 rust preventer then went over that with the high build primer

Issue - today went to put their TOP COAT on but its so thick - consistency was between a tar and a thick latex paint. Couldnt get the paint to lay flat and not have runs in it. Looked horrible so used Acetone to remove what I could.

Then tried to thin it with Xylene - that thinned it but then it wouldnt cover and still had tons of runs in it.

At this point I want to throw that stuff away and go a different route on the top coat

WAHT CAN I DO ....

thanks guys

[Getter-Done]

I have try the POR route years ago

IMHO : The high build primer is causing most of your issue.

POR likes being used on rough and rusty surfaces.

POR is best applied with a brush and thinned no more than 5%

I would go another route

[Greasey Harley]

I don't believe POR (Paint Over Rust) will adhere to primer.
I would look toward some good quality satin black chassis paint. That being said, I'm definitely NOT a paint expert.
You might also consider hitting up the Paint & Bodywork work section of the forum, you might get an answer over there.
Keep us updated.

[6600DURAMAX]

The high build primer I used was from POR - it was their product. It seems the TOP COAT is so thick .....

Can I rough up and use a high quality "spray paint" - hate using that word with this quality of build but it is just the axle housings

[Getter-Done]

Do you have a spray gun?

Maybe this black paint from TSC
And add hardner.
Link: https://www.tractorsupply.com/tsc/pr...l?cm_vc=-10005

[dmjlambert]

The way I used POR15 was to: do the cleaning and metal prep steps, then brush on the POR15. It only takes 1 coat. It is a thin paint. Let it get mostly dry but still a little bit tacky and then give it a light mist of spray on primer. Then let it dry completely a couple of days. The more humid the environment is, the faster it dries. If it is not humid at all and air is very dry it could take some days to dry.

Then do whatever other stuff to it such as put on a full primer coat and regular paint. What is this tar to thick latex paint consistency top coat are you mention? Is that something else by POR15, the same POR15 paint that went on before except now it is thick for some reason, or some other product? It seems whatever you are using for the top coat may be old or has some sort of problem.

[May70]

Are you saying the top coat material was too thick and laid out tar like? That's not a problem with the substrate, that's a problem with the top coat or the application of the topcoat. If its that thick it either needs to be thinned or thrown out. Old can? If so id trash it. Not familiar with the TDS, what does the TDS say? Can you thin it and by what/%? Sounds like an old can possibly that you then put too much thinner in or possibly NIAW the TDS. Letting paint in the can or after application (before cured) get too cold can ruin it.

I have seen several failed POR jobs. I think its great stuff when used to pretty up something, as long as its applied over knocked down rust. Issues I have seen too many times come from using it on fully prepped metal. Many people use it without issue but the few that have issues I know of, it screwed them to the point they had to go to bare metal and restart.

At this point I would let it fully cure, then feather all the rough spots out here you tried to remove the topcoat. I'm sure that probably doesn't look too good. With the material you have on it now, id scuff the rest and use a sealer/topcoat of another product. Or risk trying to topcoat it with what you have IF you can get the consistency right on a test piece. I wouldn't spray POR. If you cant get it to feather out, id have it blasted and just go with a sealer/single stage topcoat

I'm no painter but I've had my share of bad experiences. GL man! Paint issues suck, maybe try the paint/body section folks.

[6600DURAMAX]

Thanks guys -

Yes this TOP COAT is a POR product - suppose to be UV resistant ect...

I like the plan of scuffing it and laying a nice coat of whatever else....

Any good quality paints that can be sprayed out of a can?? I have a great base now

[davischevy]

I've used POR with good results over rust but I wasn't trying to get a pretty finish either. It is tough as nails, but not the look I want.

It sounds like your POR is old or got air to it. It should be the consistency of a good quality house paint.

My go to chassis paint for over thirty years has been Rustoleum code 7777 Satin Black. It's available in both cans and spray bomb in most hardware stores.

[truckster]

I used Rustoleum on mine. So far it's holding up well.

[atog]

If you mix rustoleum satin black with flat black it is identical to gm chassis black. True story

[6600DURAMAX]

Will there be an adhesion issue with the Rustoleum over the POR? I would scuff it up with 220 or 320 before application

[pwdcougar]

From what I remember the reason for the POR high build primer is to bond the rust preventer paint with the top coat. The primer has to be applied (or a top coat has to be applied) to the rust preventer paint when you have a slight finger drag in the paint and it isn't fully cured. Once the rust preventer paint is cured it is almost impossible to get a top coat to stick to it. By applying the POR primer at the right time it makes it possible to coat it with the UV protective top coat.

With the POR primer on the axle you can now paint it with any paint that is compatible with the primer. It sounds like the UV top coat is bad if it is that thick. I had a similar problem with the KBS top coat which is a similar product to the POR.

[69GMC2004]

I used POR15 on my frame and axle, the finish was terrible so I grabbed a few cans of VHT chassis and roll bar paint and painted right over the POR (it acts like a primer if I remember correctly). Looks much better now and have had no issues.

[allchevy58]

On my 64' I pressure washed real good, wire brush a few spots, wiped it with grease and wax remover and brushed on thin enough not to run. Still looks good.