Here are the replies and comments from several site I posted these tests on:
From Garage Journal.com
"I have read on several forums that POR15 will not adhere to new metal. I have no idea what type of metal prep, if any, was done."
It definitely DOES NOT adhere well to new, SMOOTH metal. It needs something to bite into, either surface rust, or properly prepared new metal. You can either sand it with 80 on the DA, grind it, or use Metal Ready/MetalPRep/OSPHO, etc. . They do the job by roughening up the metal enough so that the POR15 can bind. It also doesn't stick to previously painted surfaces without proper prep either.
"Is there a recommended time limit before sanding POR-15? Due to the fact that I brush it on, I'd rather try and smooth it out before applying primer and paint."
It does a great job or self-levelling itself, especially if you apply thin coats. If you are going to top-coat with primer or paint, either do so after it's dr but before 24 hours, or - if you waited longer - use their Tie-Coat primer to tie the two products together.
"Forgot to say, thanks, E-tek! You got me thinking about these products again.Have you done anything with internal (cavity) rust proofing/preventing? I was going to go with Waxoyl (Waxoyl 120-4) for the inside of my Landy's frame, but cheaped out and bought a couple aerosol cans of Eastwood's similar product instead."
I used Eastwood's Internal Frame Coating and wrote it up on my web site. It seems like it would do the intended job of repelling mositure, since it's an oil/wax substance. I did like the applicator they've come up with - it has a long tube and a broadcast tip so you can get it all the way into enclosed areas like frames and body channels. I haven't looked at long-term results yet through.
"I used Eastwood's Rust Encapsulator on my truck frame (bought a kit) and I'm not impressed. Not long afterward, the rust started to return. The rest of the Eastwood products found their way to the trash can, I will use POR15 from now on..."
Thanks for adding your experience.
"I don't want to hijack the thread, but in the case of my frame, I am going to have it blasted, but wanted to POR-15 or Rust Encapsulate it also. POR-15, especially, I've heard creates a super hard shell, which I like the sound of. Mostly, I'm just going for overkill here in case any microscopic traces of rust survive media blasting."
My preferred method for frames and body panel undersides is just that: sandblast, wipe down with a wax&grease remover and apply 2 coats of POR15, each applied thinly by brush and within 8 -16 hours of eachother.
From the Stovebolt Forums:
"you don't have to sell me on Por15. It's been my drug of choice for years.
I had to grind some off the chassis to weld a bracket for the power steering box on my panel. While I'll admit I used a flap-disk on it I could still tell its some tough stuff. Nuff said!."
"In using POR as a stand-alone product, painted over slight surface rust as you described, it was on there as if it had been powdercoated. Smacked it with a screwdriver a couple times, didn't even leave a mark. On another occasion, we had some bare metal with some factory finish paint (from mid 50's) next to it, and the POR was used to cover both surfaces (for consistency). After curing, the POR peeled off in sheets from the painted surface."
Number ONE most important thing about POR15 is that it NEEDS soemthing to bite to. Rust is perfect, but if you want to coat new metal or previously painted surfaces, you have to prepare them properly. New metal can be prepped with their Metal Prep, which gives it a slight etch, or it can be sanded with 80 on the DA, or hit with the grinder (though I'd still go over with the DA to make sure it's evenly scuffed). Painted suraces have to be well-sanded. I'd go with 320.
Don't forget to check out the website at www.E-tekRestorations.com !