Por-15 or epoxy primer

[arnolddyer]

Has anybody used POR-15 lately? Is it new and improved? I've read the past posts that some liked it and some didn't. Is it better to just use epoxy primer?

[Carbuilder]

We use por 15 in the shop all the time on all the panels that we replace. It seams to work well no problems.

[MP&C]

I have used it before on a piece of metal that had a slight bit of surface rust only, and the stuff was on there like it was powder coat. Then I've also used it before where some of it covered some of the OEM paint, and it peeled off in sheets.

Since having this "compatibility issue" in conjunction with other paints, I typically use epoxy primer if it's meant to be used with another paint, especially if I have full access to properly prep/abrade something by removing any surface rust. If it does have scale, it's only a few short steps away from pin holes. I'll test the integrity here with an ice pick, and if it fails, install new metal. Based on my experience with POR peeling, I do not consider it a good medium in conjunction with other paints. Even though I don't care for POR based on the incompatibility issues I have seen, I do find it has it's uses. In particular, I do use it in inaccessible/not visible areas, such as down inside door skins to seal up the seam between the layers, inside cowl vents, rocker panels, etc. where you can't get to for proper prep.....but only after insuring the metal is still structurally sound. However, if I am installing new door skins, the inner door gets sandblasted, the inside of the skin will be prepped, both epoxy primed, skin installed, and then more epoxy used to seal between the layers. Again, access is available to properly prep, so I use Epoxy. Perhaps my thoughts have also been swayed by having to fix far too many cases of Harry Homeowner misusing the product to cover rust through and scale on something that needed obvious metal repair. It's a pain to remove, and puts off noxious fumes from any heat due to welding.

I'm not discounting Danny's or any other member's successful use of the product, but personally I've had better luck with epoxy, and given the possibility of delamination of topcoats, will tend to use epoxy before POR if other coatings (topcoats) will be used.

[Carbuilder]

Just to clarify we use it on the inside of our panels. Example we cut off a quarter panel for replacement. We then replace all rust thru & pin hole in the inner structures. After that we derust as much as possible of the surface rust showing. Then we coat the cleaned metal with Por 15. It needs a ruffed or 80 grit scuffed surface to stick well it will then ad hear real well. I should of made that more clear in my last post.

[arnolddyer]

Is it possible to apply any kind of filler bondo or fiberglas over por or epoxy primer. Arnie

[welderboy]

This stuff is the bomb. it isnt UV so it will chalk without topcoat but still durable. It even comes in spraycans now! You must use adhesion promoter found at local paint store to topcoat with any auto paints

[Roger J.]

Be sure to consider the safety issues with Por-15 vs. epoxy too. Por-15 contains isocyanates just like automotive clear coats and other urethanes.

Read the MSDS sheets and protect yourself properly.

[MP&C]

This stuff is the bomb. ...... You must use adhesion promoter ...... to topcoat with any auto paints


That's the exact reason I prefer Epoxy. You don't need an adhesion promoter as it is designed for use with other paints.

[tusk]

You can beleive what you want. I beleive most people use it and then never see that panel again cause its gone (customer project ) or its covered up by another panel.
I,ve tryed it on my everyday junk errr I mean my trusty and rusty michigan cars and trucks
I put it on bare interor s-10 floor and in 2 years it had all pealed off,had rusted under it and my floor was gone.
Under mower deck? Hard as rock? Gone
I was told I wasn't using it properly need to use eching stuff and rise wit water, use marine clean and rinse wit water. So I used it under a car tat had not much rust at all under the car, took days for everything to dry under car, floor, boy this better be good, its a week process.
About 3yrs later (last winter) had it up on jack stands, lookin, of course I got more rust, that to be expected. POR stuff was there but it was rusting like crazy under it and it look like a big blister, pimple....
I had a very hard time (being nice here) gettin the stuff off so I'll not be using POR-15.

[CARS]

You can beleive what you want. I beleive most people use it and then never see that panel again cause its gone (customer project ) or its covered up by another panel.
I,ve tryed it on my everyday junk errr I mean my trusty and rusty michigan cars and trucks
I put it on bare interor s-10 floor and in 2 years it had all pealed off,had rusted under it and my floor was gone.
Under mower deck? Hard as rock? Gone
I was told I wasn't using it properly need to use eching stuff and rise wit water, use marine clean and rinse wit water. So I used it under a car tat had not much rust at all under the car, took days for everything to dry under car, floor, boy this better be good, its a week process.
About 3yrs later (last winter) had it up on jack stands, lookin, of course I got more rust, that to be expected. POR stuff was there but it was rusting like crazy under it and it look like a big blister, pimple....
I had a very hard time (being nice here) gettin the stuff off so I'll not be using POR-15.


I completely agree with what you are saying. I have had them all fail (POR, Chassis Saver, Eastwood's rust encapsulator, etc) BUT, I do use it on occasion for what Robert is using it for. Pour it in a trunk lid, hood, doors and slosh it around. It has to be better than nothing :confused:

I have had it peel too though and got the same run around with "my improper preperation" from the companies... :mad:

My general concenssus is "Snake Oil", but you can't reach everything :rolleyes:

[Overkill]

Just talked to a guy that does Mopars. He takes a Hudson sprayer (garden sprayer), puts a flexible hose on it, then a mini sprinkler in the end of the hose, threads it down into the frames, and coats the area from the inside until it drips out. Interesting idea.

As for "bondo" over epoxy - many times it works, but I had to have a car blasted a second time because it the Rage lifted the DP90 epoxy primer. After hours on the phone with tech people at both companies, they admitted it happens once in a while and they don't know why. Rage pointed out their materials say to put it on bare metal, but agreed that many people don't. My buddy has been putting it over DP90 for decades, and never had the problem. Didn't make me feel any better about having to do the job twice.

[Philrally]

Epoxy has to be fully cured before using bondo. That is a min of 24 hrs. Some paint companies say a week. Try sooner and you will definately be doing the job twice :o. The bondo will fall off.

[Overkill]

In my case, it sat for several days. Tech guys couldn't figure it out.

[tusk]

I have tryed rust seal, I think that was it and didn't care for it.
I tryed Rust Bullet and kinda like it. Its sliver UV protected. I bought a rusty bush hog, rusty to the point where the top deck is or was about 1/8" thick, in some spots it rusted to dimples then to nothing.
I wire brushed it with my grinder after knocking the heavy rust off, then wiped it down with laquer thinner and painted it . Came back the next day and gave it a second coat. can't remember if I did a 3rd coat but the brush hog hasn't been used for over 5yrs sittin there with snow,water leaves,pine needles and dirt on it. I looked at it and I do see some red dots here and there tryin to come thru but at least no blisters.
Not perfect but the best thing I've found so far.
Opened the tailgate on my pee-cup the other day and it fell off cause the one hinge rusted. repaired the hinge and yup tomorrow I'm paining the inner bottom of the tail gate and hinges withh Rust Bullet, 3 times