Should I por 15 the inner fender, or just epoxy prime and seal the whole thing, inside and out,,, Thanks,,, Stan
POR 15 is good stuff. Most times brush it is good enough. Needs to be a rough finish for the POR to stil.
Por 15 is great stuff for sure BUT make sure you DON'T spray it unless you have a respirator and damn good ventilation. About 3 seconds of spraying it on my 55 without one and my lungs burned for 3-4 days.....
Much as I like and use POR 15, I don't use it on things that get painted nice. On your inners...I'd prep and paint the engine side with epoxy and paint....POR and undercoat (or bedliner) on the street side.
POR 15 has a place and I will repeat my comment about it over and over and over. .. What is wrong with paint? Paint does a really good job. It's easy to work with. It adheres well and is long lasting. Plus if you are going to see any of it, it will probably look better. Paint.
I'll go along with most of the rest here. Unless the part was previously rusted and out of sight, go with the epoxy. (This coming from a guy who did the chassis of his '51 Ford with POR-15 in 1987 and is still happy with how it looks today.)
POR 15 is good stuff, however it was designed to be applied to rusty metal not new metal or clean metal. I think they came out with a primer or a POR 15 that can be applied over clean or new metal? A DP90 primer is probably all you need if it's new, blasted or clean metal. I've had good luck with Rustoleum "clean metal primer" on sandblasted metal, really durable stuff!
Epoxy paint for sure, its good stuff and will leave a nice finish when top coated. A buddy of mine used por 15 on a truck frame and 5 years later he noticed some of it flaking off. Turned out the frame was rusted bad under the por so off it came and he painted it with red oxide and top coated with rust oleum. Still looks good 10 years later.
I've seen POR15 come off clean metal in big sheets. It's designed for rusty, or very porous-rough metal, and on clean smooth metal it doesn't bond well.
I've had mixed results with POR 15. From apparent success in one case to being able to peel skin-like strips to experiencing continuing rust. I've studied the tech sheets and followed them religiously from recommended proper prep to recommended mil thickness and followed them to a tee. I've bought and used the zinc phosphate prep, the "perfect adhesion for POR 15 on any surface". Still peeled. I've noticed when looking very closely at a coat after drying it seems to pull away from the edges of the rust "craters" so I worked at building up multiple coats. Still rusting continued at times. Won't even start with Rust Encapsulator. I switched to Rust Bullet and the jury's still out after 5 years and counting. But I'm now gun shy with these kind of products and nothing will surprise me at this point. There's guys who'll swear by POR 15. I swear at it.
Just my 2¢, I did a little research a while back into direct to rusty metal paints, like POR 15. One paint company I talked to told me that POR 15 was an acrylic mastic the guy suggested I could use an epoxy mastic. Epoxy mastic is used for priming hard to clean structures like bridges and storage tanks. I bought the PPG epoxy primer from my local hardware store for about $100 for a two part, two gallon product. I've sprayed it on the frame of my car and it seems to turn hard as nails. It dries to a matte finish, not shiny like POR-15. Unlike POR-15 it will adhere to non rusted and smooth metal. You can also top coat it without like most other primers. With POR 15 you have buy extra products to make a top coat adhere to it.
Por 15 is a band aid for those to cheap or lazy to remove the rust. Once you've prepped the surface properly, I don't see any reason not to use anything but quality materials.
Hey, Por 15.................... with the possible exception on medal laden plastic fillers, the most over hiped, over sold automotive paint product on the market today. Prep your metal correctly, and leave these products for use by those trying to roll a turd in glitter! " Do not reach greedily for the Kool-Aid "
What he said, if you want a good finish use the correct automotive products.Do it rite the first time and save yourself time and money in the future by not haveing to redo it.
I just knew this would turn into a "Por15" bashing thread. They always do. I've used it for years and always with good results. Got know idea what I'm doing right.
Yep, and I've got a frame that was POR'ed by a previous owner 3 years ago that is now starting to have rust bubble flaking issues.
based on my results with POR i would say the DP epoxy primer would be better. you should use a mask when spraying the DP.
When you say inner fender, do you mean the separate part that you see from the engine bay or the back side of the outer fender? I'm going to mention a car like 1 of mine. The best use of POR-15 on a fender would be to get it behind the reinforcement that runs top to bottom near the door jamb. In order to use it (or any rust bond mat'l) it needs to be free of the loose "crumbs" associated with rusted steel. A high pressure power wash does well for that, then it needs to be dried out, preferably for a couple days. Once dry, lots of compressed air and be sure it's free of loose material, then with an over loaded brush or even a small cup, get it to run in behind the brace and try to get it to seep through the spot welds on the edge. At that point you'll never see rust form at the bottom of the fender for as long as you live (the spot where most GM cars rot out). For the separate inner fender, satin black epoxy works fine but it doesn't like a lot of sunlight. If you're going to hang out at a show with your hood up you'll see it go chalky in a year or more. Better than any paint, try chassis black powder coat. The cost is about equal to the cost of materials and no labor, it's generally color fast (UV stable), and it ends up looking like a new OEM part if you're starting with one in good shape. Seeing a core support, inner fenders, heater box, and the few other misc parts done that way nets a nice professional look and it's quite durable. If it's just the inside area of a fender that's OEM painted on the outside you can't beat a decent coat of epoxy over properly cleaned steel. If the timing is right, some epoxy finishes can be sprayed over w/out sanding for as long as 3 days. Read your tech sheets to clarify that, as not all epoxy primers are created equal. Good luck...
Late to the party, but POR-15 is, IMO, extremely overrated. It's finicky to get it to adhere and basically has the same finish appearance as Tremclad. It is also not able to withstand UV exposure, keep that in mind wherever you put it. Also, its expensive. I've used it on inner fenders and frames. It didn't seal the rust away on the inner fenders as claimed, it rusted out from the inside under 2 years. Other than that I've dumped it in unibody frames as a last ditch effort. Used it until the can was empty/dried up. Hard no for me. IMO appliance epoxy enamel is just as good and much cheaper.
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