Bad results with POR15

[Allenk]

I used POR15 to treat the underside of my welds after putting SC flares on and I noticed some surface rust bleeding through. I was hoping the POR15 would give some piece of mind that I would not have rust through or moisture bubbles from the backside after painting but now I think I'm in the market for different product.

[john walker's workshop]

it sticks to rust better than other things, like bare metal.

[Allenk]

Any suggestions regarding how people are sealing the back side of welds that will have weather exposure? I did use a halogen lamp to look for pin holes but truth be told sc flares are a lot of welding and missing a couple, resulting in bubbles would suck.

[RichF]

I hear ya POR-15 let me down also. I purchased a wheel polishing kit and it did not preform well at all. I called them and they have been bull****ing me for about two weeks now on a return or replacement of some sort. Being 19 and paying for my p-car by myself and anything I do really pissed me off that I waisted my $170 on it and then had to pay $330 more dollars to repair the wheels professionaly and knowing I could of used it towards something different. Just my rant.

[john walker's workshop]

how about spray cold galvanize followed by autobody seam sealer, like auveco.

[DanielDudley]

You are supposed to brush on two thin coats. If you have pinholes, POR 15 makes an epoxy putty that is compatible with POR 15. I have used their products to seal pinholes in gas tanks, so I think it would be appropriate for your application. Did you use marine clean and metal prep before painting the stuff on ? I would do a skim of epoxy and second coat the whole shebang. Rough it up a little first.

I think there is a learning curve with new products. There may be better ways to skin the cat, but this product has merit. YMMV

[Allenk]

I guess at this point it's a trust factor. I have this produst on many areas of my car but really, the exposure to elements is much greater on a quarter panel since moisture exposure is from both sides. I have used POR Patch in combination with POR15 and it seemed fine but I don't like what I see here. JW makes a good point in that these where good clean welds and maybe another coat over the areas rusting would do the trick. Then again I could just coat it in grease right?

[Zeke]

Originally posted by Allenk
I used POR15 to treat the underside of my welds after putting SC flares on and I noticed some surface rust bleeding through. I was hoping the POR15 would give some piece of mind that I would not have rust through or moisture bubbles from the backside after painting but now I think I'm in the market for different product.

Bleeding through what side, the top or outside? You can't leave any holes, POR 15 or otherwise. If you are examining your welds with a light (which is a neat trick) and find a pin hole, just use common solder to fill the hole. Clean up the flux, et al, perfectly clean and prime with a suitable primer.

The weld itself has to be perfectly clean, too, before soldering, brazing or painting. I like to go over them with a spot sandblaster. That will get the crud, slag, whatever out and expose any pin holes you otherwise might not see, even with a light.

[Allenk]

I had some rust staining through the front(outside) that I had primed with high build primer. When I looked inside the wheel well I saw areas where the POR15 didn't seem to seal and corrosion had started.

[berettafan]

Am i reading right that you DON'T want to clean off all the rust before coating with POR?

I have a front pan project i'm in the middle of and after reading the POR brochure i was pretty excited about trying the stuff. However i certainly don't plan to leave rust in an area where i can easily wire wheel it off. Right?

[herman maire]

This stuff is F'ing garbage and I will never use it on one of my cars again, at $145 a gallon + shipping I got ripped big time.

I even asked the rep before I bought this stuff that I wanted to use it on a sand blasted surface on the floorpan, he said it would be perfect. I have the same problem with rust starting to bleed through... my brother also has this same problem and its a major bummer after you bust your A** restoring your car and you have rust bleeding through after only a few months.

Next time around I am going to use a etch primer and rubber coat it... I really hope it turns out better. Maybe POR works on REALLY,REALLY RUSTY surfaces, who knows.

[Porsche_monkey]

For the guys with poor results: Did you do the recommended surface prep?

I sandblasted a floor pan, washed it with laquer thinner and sprayed on POR. I did not get good adhesion, it was okay, but not good.

On another project I bought POR AND their surface prep product 'Metal-Ready'. When I used it as directed the adhesion and finish are 100% better than before. I was totally impressed with the results.

If you used their products as directed and it failed then by all means slag them, but if you just painted bare metal you can't blame POR.

[klaucke]

If you have bare metal (true bare metal, i.e. sandblasted, and not just rusty metal that has been wire brushed) then there seems to be no reason not to use a good 2-part epoxy primer/sealer like PPG DP-40-LF. It is meant as an undercoat (even under body work) to protect the metal, and the stuff is extremely durable. I would use a product like this.

[berettafan]

PBH i too am interested in the answer to your question....

[Porsche_monkey]

Originally posted by klaucke
If you have bare metal (true bare metal, i.e. sandblasted, and not just rusty metal that has been wire brushed) then there seems to be no reason not to use a good 2-part epoxy primer/sealer like PPG DP-40-LF. It is meant as an undercoat (even under body work) to protect the metal, and the stuff is extremely durable. I would use a product like this.

Thats a valid point, and if you are going to paint over your work, a primer sealer is much better than POR. But I guess there a people who have bare metal and rusted metal to cover, and POR should be able to do both, from what they claim.

[berettafan]

So if i'm just wire brushing the metal i should still use POR vs. PPG primer/sealer?

Still interested in hearing from those unhappy regarding prep done.

[Allenk]

I removed all loose scale and cleaned the remaining area with a wax and grease remover befor applying. I was of the impression the benefit of the product is that it will encapsulate any remaining rust giving a sealed protective surface. All that being said, I must say not all applications on my car are having this problem. Areas that do not involve two sided exposure ( say the floor pan with surface rust) are not showing any rust. It's not an adhesion issue, I have scraped at it and it is firm, not chipping or flaking it just has surface rust coming back through.

[Classic]

I think it might be a fact of no rust.

I did my engine bay with POR, and yes i used there cleaner and then metal ready before applying 2 coats of POR applied inside there window for re coating and was quite happy, and moved onto another area.

6 months down the track i have removed all the POR from the engine bay, as you could see rust creep every where.

Of interest when i removed it you could see that it hadn't adhered to sections of shinny metal, maybe i should have hit it with the DA to give it some tooth.

Anyways, it's gone now, and I've media blasted anything that looks like rust, next I'm wiping it down with Picklex metal conditioner and then applying 2 coats of epoxy primer, seam sealer and then wurth SKS.

[Porsche_monkey]

From their website:

WHAT IS THE BEST SURFACE ON WHICH TO PAINT POR-15?

POR-15 likes rusted surfaces best. Seasoned metal and sandblasted metal are also good. POR-15 does not adhere well to smooth, shiny surfaces, but will adhere well to those surfaces with the proper preparation.


WHAT IS THE 'PROPER PREPARATION'?

We make a product called 'Metal-Ready'. It's a rust remover that leaves a zinc phosphate coating on base metal, the perfect preprimer for POR-15. NOTE: New steel is coated with a protective oil finish

Sounds like a crappy rusty surface is best for POR. Otherwise a good two-part epoxy primer would be better. I think I saw a DuPont brushable primer.

[berettafan]

wow, this seems to be a pretty big deal.