The Stovebolt Site Forums The Shop Area Paint and Body Shop POR 15 WHAT WENT WRONG ?

I tore my truck down for a complete rebuild ,and decided That I would use POR 15 on the frame after talking to other people that have used it and also the people at Por 15 who told me I wouldnt have to do anything after having it sand blasted other than making sure it was clean and dry and brushing it on.Well I had my frame blasted and brought it staight home and put in the garage and put two coats on it ,and it looked great.Now about six months later I can see where rust is coming to the surface in places.I feel like I have waisted a lot of time and money ,and now are are probaly going to have to get it blasted again and just have it painted.Has anyone else had an issue like this?
Thanks for your advice

did you use metal ready?

No ,the folks at POR 15 told me as long as it was sandblasted to bare metal it was not needed.

Hi Longhorn, I am a long way from being an authority on POR 15 but I have an opinion on what went wrong. POR 15 reacts with iron oxide to create new chemistry that is important to how well it "sticks" to the metal. If you had the frame sand blasted there was more than likely no rust left for the POR 15 to react to. I am not sure having the frame sand blasted and then using POR15 was the right thing to do. I think you would have been better off using a good quality primer and paint after the sand blasting. Not what you wanted to hear, but better to figure it out now when the body is still off.
Rick

POR-15 APPLICATION PROCEDURES

Surface preparation:
Rusted surfaces are best; seasoned metal and sandblasted surfaces are also good.

To coat smooth metal surfaces:
Use POR-15® METAL-READY to prepare surface before painting. Surface must be dry and free of grease, oil, or other foreign substances. Use of 'rust converter' products is not recommended as they may affect bonding of POR-15® to metal. POR-15® likes to adhere to surfaces with 'tooth' rather than smooth, glossy surfaces.

STIR CONTENTS GENTLY AND THOROUGHLY before painting.
Do not shake.
Refrigerate unused portion of POR-15® for longer shelf life.

Apply in thin coats, 1 to 2 mil thickness. Minimum 2 coats.
Topcoat when first coat is dry but with slight finger-drag remaining, usually 4-5 hours.

Did everything but use metal ready.My mistake taking for granted the person on the other end of line selling there product new what they were talking about.

Longhorn, I have used POR15 several times on gas tanks, and chassic's and have had great results. A year ago I blasted my fame with medium sand with my pressurized sandblaster and then put the POR15 straight onto it. It looks really nice..... later I had to grind some off to attach a power steering bracket and that stuff is tough! It still looks good to day.

I don't know what happened and I"m only suggesting what MIGHT have happened. Did the frame get moisture on it before doing the stuff?? (...of coarse the POR is suppose to stop rust)
After the first coat did you wait the recommended time before putting on the second coat? The second coat is suppose to be put on while the first coat still has a little tack/grap to it. If it dries it will have a gloss slick finish and nothing for the top coat to hold onto.
Did you thin the POR?? For the rust to come through you'd think the coverage was not that good??

Bottom line is I really don't know. I have used it sucessfully and I might add that the last frame I did I only put on one good ooat and it is holding up well.
Let us know if you find out anything else. I'm curious.

AChipmunk,My sandblater uses coares sand ,I picked it up as soon as he finished it ,and it had a good bare metal rough finish not smooth wich I would think would be good.
I had the first coat on withen an hour .and then applied another coat before first had hardend.
I have the frame on jack stands and covered up with sheets to keep the sun light off of it coming through the windows.
I was going to put my dropped axle on today ,and noticed how you can see the rust in several area's coming thru the POR-15.You can take a paper towel and wipe over it and see the rust on the towl.I live in Houston Texas where it is very humid but I wouldnt think that would have anything to do with it.
I guess I will have it blasted again and have it primed and painted .I hate to spend the money to have blasted again and painted ,but I dont want to take chance of this happening again.

Is the frame exposed to uv/sunlight where the rust has bled through? If so, then you must know that the por 15 is sensitive to this and uv can cause it to degrade. That is why they recommend a topcoat. Just a thought. I had no problems with their stuff, but used the metal ready as well.

I read the part about the sheet....just don't know if that was enough to protect the surface w/o topcoat.

Hank

No, I am well aware of the uv sensitive issue,the frame has been coverd in my garage with sheets for that reason.I probaly would have noticed it sooner.

The myth that UV Rays degrade the durability of POR-15 is one of the biggest on this site.

Quoted from the POR-15 Application Sheet:
(Second Page, Left Column, About Half Way Down)

WILL THE SUN DESTROY MY POR-15 COATING IF I DON’T TOPCOAT IT?
No, your POR-15 protection will remain, but the sun will change its appearance cosmetically. That’s why we recommend you topcoat it.

Another Quote from the POR-15 Application Sheet:
(Second Page, Left Column, Near Top)

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 with the use of Marine Clean and Metal Ready preps.

A Link To All Information About All POR-15 Products

For my frame we sand blasted, brought home on open trailer while it was raining. After it was home it was outside until we were ready to paint. Then the night before we pressure washed it with a diluted Marine Clean mixture as per the directions. Then inside over night, one coat applied and second coat applied. Did this in August of this year still no problems.

I did mine back in '96. Didn't sandblast, just thuroughly degreased them prepped with Metal ready. 2 coats, sprayed on. haven't had any troubles. Also did the bumpers, insides of the fenders, and the cab corners. Still holding up fine.

I have a bumper I sandblasted, painted with a corrosion resistant two part primer, and topcoated with catalyzed enamel six years ago. They have been stored inside until two months ago. There are now a few spots with a little rust coming through. I'm not going to sweat it or resandblast it/repaint until it gets to looking bad. POR- 15 is great stuff, but not perfect. As i understand it, the UV problem is cosmetic rather than rust preventive. In other words, sun makes it look lousy without affecting the rust stopping quality of POR-15. That said, i have some 2 year old exposed spots of POR-15 not topcoated that have rust in spots. I'm not clear whether you have a big major rerusting problem or some spots here and there. Resandblasting seems like a lot to me, and just abandoning POR-15 for something that may well not work like POR 15 is setting yourself up for frustration.

Also, the POR-15 folks say that while the stuff is catalyzed by water, the surface should be bone dry when you put it on. That could be where the local humidity might be a problem if there was any condensation on the chassis. I might try sanding the rusty spots a bit, hitting them cautiously with a heat gun to dry it well, then try more POR -15 and see what happens

That is my two cents.

I have did both the POR 15 and powder coat on frames. POR 15 needs to be top coated. I have been using an epoxy primer followed by PPG paint (color depending on project).

I have had great results.

The Powdercoat is the best route based on cost and time. (It was faster and cheaper to have a frame powder coated after I compared all the costs)

I used POR 15 and their chassis black on the sub-frames and suspension for my Audi and VW back in 2006, spraying the product after sand blasting There is rust showing thru in areas.

So, my conclusion is sometimes it works really well, sometimes it doesnt, however I have had the best results with POR 15 when I top coated with Non-POR 15 product.

I am betting that humidity is the culprit and the reason why some people have had good luck painting right on the as blasted surface (without using Metal Ready).

Since you are in Texas (and it is humid) there was a higher level of moisture on the frame before the POR 15 was applied.

Just my 2 cents........

I used Zero-Rust on my frame in 2004 and I have found zero rust.

Hello all:
What a discouraging bunch of letters. I thought Por 15 was good stuff.... I am not up to the frame painting stage with my project but was planning on using it.
Hope this discussion keeps on with more suggestion and hopefully more success stories
Ter

I have used POR-10 and POR-15 many times and have had no problems.

Freshly blasted shiny metal should not be covered with POR-15 (this is described in several places on their website).
POR-15 that might see the light of day should be covered with a sealing paint (an enamel, I prefer an epoxy or a urethane).

The outer roof of my Suburban is the largest surface that I have painted with POR-15 (it was actually POR-10 at that time, over 7 years ago). The roof was heavily rusted and pitted. We covered the POR with an epoxy primer, a sealer surfacer and then a single-stage, two-part urethane exterior enamel (PPG DCC). This has held up completely after 7 years (and, much sunshine, and, I regret to say, some substantial rainstorms). I have never waxed the surface and I clean it thoroughly one a year.

The underbody of my cabs and fenders get coated with POR-15.

I am using it on two restorations - on metal and on bed-boards.

This is my second two cents, in response to the person discouraged about POR-15 by the thread. I think the stuff is great. It has more toxicity than some other products, but what sold me was seeing a sample on sheet metal at a swap meet that the guy bent back and forth, and the stuff did not crack! It is also great for some spots that are pinholed and that blasting would obliterate. Using their fibre glass sheets with POR 15 saves for me some otherwise unsavable places. I painted my whole truck with it- the '56. I sanded the whole thing (not to bare metal), treated it with Marine Clean and Metal Ready as specified in the directions. Then I coated it with Tie-Coat followed by a two part urethane. All products are by the POR 15 folks except for the urethane, an Omni AU product by PPG. So far so good, but I did it this fall. The stuff does not last in cans, so buy what you need and use it up.

All the best,
Dave

I have had this problem on a couple of spots and I am almost positive that I did not have the surface clean enough. I used acetone before painting on the underside of my hood almost two years ago and it still looks fine. Overall I think its a great product and very tough. And it might not be that easy to sandblast off. I know I had to use a sanding disc on an angle grinder to get a couple of runs out.

I used a different product on my truck frame. I have been using Rust Bullet (of Texas)for awhile. It is used straight from the can, no mixing, and can be sprayed, brushed or rolled. The best looking results are from spraying. and the mfr say that it works best on a roughened surface. It won't come off of skin without abrasives, and I've given a couple of sprayers to the bin, because they couldn't be properly cleaned. The finished product is silver but the sun will turn it to a champagne color. It has a discoloring reaction to UV rays, and should be topcoated. Rust Bullet also has a newer line of black that doesn't react to sunlight. Tough stuff. You can buy it from Summit, or the Rust Bullet of Texas site. I'm in Houston, and there is always lots of moisture in the air, except for a few days a year.

Thanks for calling me out there Chris. Here's where my non-myth info came from:

http://www.por15.com/POR-15/productinfo/1GB/

Last paragraph before the pricing:

POR-15® is sensitive to UV light (sun) and must be topcoated for prolonged exposure to sunlight.
Topcoating is not required for areas not exposed to sunlight.

Your right, I did not read the msd/app. sheet but I took this statement from their website at face value. I am not in the myth business my friend.
Hank

I was just reading one of my 4 OZ cans of POR 15 under application procedures it says{IF SURFACE HAS BEEN FRESHLY SANDBLASTED YOU CAN JUST BLOW OFF ANY LOOSE DUST OR DIRT THEN APPLY POR-15 DIRECTLY OVER SANDBLASTED AREA} WICH IS WHAT i did and I confirmed that with the folks at Por -15.I think they probaly have a great product and that I should have went ahead living in a high humidity area, went ahead and used the metal ready and I would have been fine. This mistake is going to set me way back on my project and cost more money.If I can give anyone any advice on this ,it would be to use the metal ready,reguardless.

you might consider exactly where the bleed-thru is happening, it may be that some areas didn't get enough film thickness, or maybe it's happening around places where joints of cross members or mount pieces didn't get cleaned well or didn't get enough paint wicked in .... might be dealt with by just cleaning and recoating those particular areas rather than a complete stripping and repaint

Bill

Sorry to hear of your results.

I used POR 15 on my frame over 7 years ago. I don't see any rust. You must be on the other side of Texas.

When I was looking at POR 15 for my frame I seem to remember that one of the things they said was that if you did have rust in an area that the POR 15 would help stop the spread of rust, anyone else read this? If that is the case, I would hope you could just do some repair and not have to redo the whole thing.
Rick

I used POR 15 on my 53 truck frame, used a putty knife to get the scale off and then used POR 15 Marine Kleen as directed. This stuff is as tough as nails!!! I have also used it in the dump bodies on my dump trucks and its still holding up. I'm a true believer in this stuff!!!

Longhorn,
Scrape off a section of what you applied , send it back to them and let thier chemists tell you what went wrong . If you approach
them correctly they will be more than happy to find out what went wrong
Dan

Longhorn,

You do not need to sandblast again and redo it. All you need to do it take the sheen off the coat with some 600 grit sand paper, then marine clean, metal ready and reapply. It will be as good as new.

You brushed it on right? You never thinned out the POR15 did you? It seems as though it just did not cover well.

You would know if it did not stick to the metal as it peels off like duct tape, it big pieces. I do not think it had an issue sticking with the metal, it just seems like it did not cover well.

When I did mine I used metal ready and left it for a day and it rusted all to heck. I just went ahead and put the por15 over the rust and it worked excellent!