POR 15 questions

Randy'65 · May 17, 2011

A buddy of mine that restores early Broncos (17 to date) warned me against using POR 15 on new metal. He said the first Bronco he did, he stripped the frame down to the bare metal, sprayed it with zinc phosphate, and after that dried he applied the POR 15. After it dried he noticed a spot that he could catch with his finger. That spot eventually led to the product peeling off in sheets. He called the maker, and they told him there has to be rust present for the POR 15 to adhere to. Shouldn't the prep chemicals give a good surface to stick to? Or do you let the metal flash rust before applying the POR 15?

Second question concerns painting a top coat or epoxy primer on top of the POR 15. He's thinking they told him that the POR 15 still had to be a little wet before doing, or else it won't adhere. Sound right?

I'm currently stripping the undercoating off my '65 fender aprons, and am trying to figure out how much I need to get. I'm finding that under the undercoating the sheet metal is still good, can see original overspray and no rust. Only rust is at the welds/under where the seam sealer was applied. His suggestion is to POR 15 over the rusty seams, and spoxy prime and paint the rest. Any thoughts?

jadesville · May 17, 2011

Randy'65 said:
A buddy of mine that restores early Broncos (17 to date) warned me against using POR 15 on new metal. He said the first Bronco he did, he stripped the frame down to the bare metal, sprayed it with zinc phosphate, and after that dried he applied the POR 15. After it dried he noticed a spot that he could catch with his finger. That spot eventually led to the product peeling off in sheets. He called the maker, and they told him there has to be rust present for the POR 15 to adhere to. Shouldn't the prep chemicals give a good surface to stick to? Or do you let the metal flash rust before applying the POR 15?

Second question concerns painting a top coat or epoxy primer on top of the POR 15. He's thinking they told him that the POR 15 still had to be a little wet before doing, or else it won't adhere. Sound right?

I'm currently stripping the undercoating off my '65 fender aprons, and am trying to figure out how much I need to get. I'm finding that under the undercoating the sheet metal is still good, can see original overspray and no rust. Only rust is at the welds/under where the seam sealer was applied. His suggestion is to POR 15 over the rusty seams, and spoxy prime and paint the rest. Any thoughts?

POR-15 wont adhere to "clean" metal. It has to have some sort of pitting or surface rust, and with any metal you want to use POR-15 on it should be treated with a zinc phosphate product / metal ready. I've also had it flake off on me on a clean frame rail that ended up developing a surface rust pocket. You're better off cleaning the metal and removing the rust then using an epoxy primer. To topcoat it, you have four hours after applying it if I can recall correctly, otherwise you have to use their product called tie-coat or their own topcoat product called flex coat. I wouldn't POR-15 over the rusty seams, I'd remove the sealer and then treat the rust before applying a product.

TT670 · May 17, 2011

Randy'65 said:
His suggestion is to POR 15 over the rusty seams, and spoxy prime and paint the rest. Any thoughts?

Your friend gives sound advice! Also if your car is going to be a driver, its not a bad idea to spray something like sound deadener or a bedliner type material as a finish coat under the front fenders. it'll help reduce road noise resonating from the suspension thru the fenders and protect you from getting any dings poppiing up in the fenders from debris thrown off the tires.

mtaqua · May 17, 2011

I coated mine with 3M body schutz, with the no cleanup gun (while is was still tacky). Seems to have worked well so far. I followed the directions, and let it sit over night after the metal ready. From what I've read I wish I would have gone with epoxy, but like I said mine seems good so far. There are mixed results.

gregski · May 17, 2011

I am evaluating POR15 in my thread Full Frontal as we speak with fantastic results. I did strip the pieces to bare metal before painting it with POR15 and it stuck like powder coating.

67rcks · May 18, 2011

I am a victim of advertisements - also bought POR15 (over $20 for a tiny can) and painted the engine with it. That paint turned out from silver to light brown just during cam break-in (30 min?) It is very soft, does not adhere to grey cast iron, no different if not worse than regular enamel you can get for $4/big can in any local store. A low alcalic solution dissolved every piece of it while traces of original ford paint remained untouched.
You'd better use 2-component paints (urethane, epoxy) with good zinc primer.

Randy'65 · May 18, 2011

Great, so I have $200 worth of the stuff on it's way to me, and it sounds like it's a waste of money.

Let me ask you this, here's a pic of the inner fender, in the corner just rear of the drivers side hood hinge.

You can see where I scraped away the undercoating and seam sealer. The original overspray can be seen (antique bronze) around the hinge nuts, that metal is in great shape. To the right you can see the rust at the seam. Above that is the horizontal cowl joint, which is the biggest area of concern. My plan was to use a wire brush to clear away all the rust in the whole area, as well as the bits of undercoating still there, then clean, prep and por15 the whole area. What's your suggestion on what I should use and how I should do it?

dennis112 · May 19, 2011

Be sure to check out the inside of that cowling, where the seam sealer meets the apron. Under the seam sealer is where I found the worst rusting on mine.

It gave me a hint of what to expect on the inside of the cowl, directly beneath:

gregski · May 19, 2011

67rcks said:
I am a victim of advertisements - also bought POR15 (over $20 for a tiny can) and painted the engine with it.

Did you use their special engine blend or just their regular stuff on your engine?

gregski · May 19, 2011

Randy'65 said:
Great, so I have $200 worth of the stuff on it's way to me, and it sounds like it's a waste of money.

Why would you type that? Did you see my link above? The product is great if you follow their instructions. It will work just fine for what you intend to use it on, it will look like you just powder coated it. A lot of the guys who talk about how it failed, either did not buy and use all three products, Marine Clean, Prep & Ready, and POR15, and or substituted other products such as different Wax and Grease removers, or used the paint for the wrong application, engine, headers, or outside surfaces exposed to sunlight, or applied a single coat, or a single coat with something else over it, all wrong.

If you are so paranoid, than pain a test panel first.

rusty428cj · May 19, 2011

Some people like Por 15 but I will never use it in my shop.

Randy'65 · May 19, 2011

dennis112 said:
Be sure to check out the inside of that cowling, where the seam sealer meets the apron. Under the seam sealer is where I found the worst rusting on mine.

It gave me a hint of what to expect on the inside of the cowl, directly beneath:

I am really hoping it doesn't come to that. I can see one small hole from the top, and the seam is pretty rough in the one picture I have there, but looking up into the drain hole it looks pretty clean in there. I need to pull out the interior underdash to get a good look from underneath. How to treat the inside of the cowl with inhibitor without dismantling the cowl was going to be a future question topic. I really don't feel like drilling out all those spot welds.

Randy'65 · May 19, 2011

gregski said:
Why would you type that? Did you see my link above? The product is great if you follow their instructions. It will work just fine for what you intend to use it on, it will look like you just powder coated it. A lot of the guys who talk about how it failed, either did not buy and use all three products, Marine Clean, Prep & Ready, and POR15, and or substituted other products such as different Wax and Grease removers, or used the paint for the wrong application, engine, headers, or outside surfaces exposed to sunlight, or applied a single coat, or a single coat with something else over it, all wrong.

If you are so paranoid, than pain a test panel first.

What can I say, paranoia is my thing. When you break as much stuff as I do, you tend to make damn sure you know what you are doing before you mess something up.

67rcks · May 19, 2011

I then used regular $5 engine paint spray from pep boys, it holds since then. No pre-primer, special rust remover or other pricy substance was needed.
I don't like thick layers of paint other than powdercoat, because air-hardened paint will never be as hard as powdercoat. Thick layer of paint is hard to repair too.

gregski · May 20, 2011

Car guys can't agree on anything (tires, oil, spark plugs, etc.) why would POR15 be any different? LOL

lauras70mach1 · May 21, 2011

rusty428cj said:
Some people like Por 15 but I will never use it in my shop.

I wouldn't say I like it, but I use it on stuff you won't/can't see, like inside frame rails and such. I've used it on sandblasted surfaces and it seems to hold pretty good. I've also shot it inside frame rails. One old timer I know calls it "body man in a can."

chris66dad · May 21, 2011

I used Eastwoods Rust Encapsulator for the inside of my cowl based on this independent test that compared it to POR15.
POR 15 Vs Rust Encapsulator - Products Comparision Part 1
POR 15 Vs Rust Encapsulator - Products Comparision Part 2
It should not be used for any surface that will be finished with a top coat system such as base and clear.

I am a fan of epoxy to be honest

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