The POR15 vs. Ospho show-down

[straycat76]

Hey all,

I am planning on taking care of some major rust issues this spring, and after reading tons of threads and reviews, still can't seem to decide which way I want to go. And I can't find anything that shows step by step comparisons of the two in one spot.

I have a 2000 T4R Limited w/101k miles. It was a NJ/PA vehicle, so the usual major flaking and frame rot along the muffler exist. I plan on brushing off the flaky stuff, using the POR15 internal frame coating, and welding new plates over the rotted holes. However, when it comes to making a final decison on rust converter, I'm stuck. Both have big followings, and both appear to work well.

So has anyone used both products that can recommend one over the other? Whether it be due to ease of use, prep procedures, quality of the stuff, how it's handled over time, etc. I am aware that there are other brands out there as well, but I have narrowed it down to one of these two only.

Thanks for your time!

 

[jmildoc]

POR 15 or eastwood, both seem very nice and that is what i plan to use on both of my vehicles come spring.

 

[smkd13]

POR 15 or eastwood, both seem very nice and that is what i plan to use on both of my vehicles come spring.

hmmm i will be doing this process as well and have been wanting to make sure i get the best coating i can. from the looks of it POR-15 seems to be the general concensus is the better one to use. anyone have any tips for application?

 

[98OzarksRunner]

No comparison because there is no comparison. They are different products for different purposes.

Ospho (phosphoric acid) is a rust convertor. When the acid reacts with iron oxide (rust) it forms iron phosphate, turning the metal black (the iron phosphate). You then REMOVE the Ospho residue (even though their direction say you can paint over it - some primers will not stick to it because it is too acidic and they won't cure properly [ask me how I know]) and then paint over it with primer. The best procedure is to use a wire wheel or sandblast the rust down to bare metal and treat with Ospho, remove the reside (with soapy water) and then prime and paint.

POR-15 is a rust encapsulator. It does not convert the rust to anything. It simply encapsulates it in a REALLY hard paint shell so no oxygen can get to it, thus stopping further rust. POR-15 has a very specific application procedure and works best on rusty, but well-prepared metal (wire brush off loose rust, use their Marine Clean to clean it, treat with their Metal Prep solution [if smooth or new metal], paint with POR-15). If the metal is too smooth (e.g. wire wheeled smooth as opposed to sand blasted, which leaves it rough) the POR-15 will peel off like electrical tape (again, ask me how I know). POR-15 is also not UV safe - it will turn milky and chalky from sunlight.

Which to use depends on what you are trying to do, how well you can prep the surface, how you can apply it. For rusty frame rails you can do either but it might be easier to use POR-15, though it will probably cost more. That stuff is expensive. They do have some new products that apply over POR-15 rust encapsulator, like chasis paints (to provide UV protection). If you topcoat it, you have to do it before it cures or else sand it, which is almost impossible.

Edit: POR-15 is for bare or rusty metal. It won't do any good over painted metal, and probably won't stick. It has to bond with the rust/metal to seal the rust. So make sure you get all the paint off the frame.

Take their precautions seriously - if you get any on you and it dries only time will take it off. You don't want to end up looking like this guy - you'll look like him for a long time (and THAT is NOT me!).

 

[hrt4me]

Take their precautions seriously - if you get any on you and it dries only time will take it off. You don't want to end up looking like this guy - you'll look like him for a long time (and THAT is NOT me!).

How Do I Get Herculiner Off of My Hootus?!

 

[rjaudi]

I am currently using a product called Masterseries. The primer went on great, but the AG-111 black top coat is really hard to put on. However, when its dry its amazing.

 

[00_4runner]

Rust bullet.

 

[Gernn Blanston]

And...a reason for my first post.

I'm in middle of POR-15'ing my undercarriage right now- finishing up this weekend. I've followed their 3-step directions to the letter (make sure it's absolutely "bone dry" before applying the paint. That tidbit is not on the can) and so far so good. A few things worth mentioning:

-it's semi-gloss, so it does stand out a bit against the flat frame paint. Since you shouldn't use it on painted surfaces, I'm painting the side of the frame with chassis coat just so it won't look splotchy, and to guard against the little UV light that'll hit it.

-two thin coats are required. I found that much easier to do with conventional disposal brushes than the foam ones. The paint is on the runny side and the foam brushes made applying thin coats trickier, as they can hold too much paint.

-yes indeed, the paint takes days to wear off. Long sleeve shirt required, especially if you forget to do the hard-to-reach spots first and end up brushing your arms against wet paint, like this guy did.

-small modeling brushes are a godsend if you're painting the rear end while still on the truck. That's kind of "duh" I suppose but I forgot about them and I planned this job for weeks.

 

[straycat76]

Yeah, I did the POR-15 treatment on the front half of my Runner last weekend. Took off the skid plates and went to town with my wire brushes. Did all the prep and applied the stuff. I got a lot of it on parts of the frame that were still painted, however it stuck on pretty well (probably due to the wire brushing). It's a lot glossier than I thought it would be. I got to the second cross beam, right before the gas tank, before I started losing daylight.

This weekend I tackle the rear half...which is considerably worse than the front half. So much rust...so very much (had to have rot cut out and plates welded onto the inner portion of the frame on both sides). My internal frame coating spray cans came in the mail yesterday, so I'll be doing that as well.

The following weekend I'll be spraying some spray-on bedliner to the whole frame, underbody pans, and wheel wells. It should be a tank underneath at that point.

 

[woodro]

i had a rust problem with my 4runner , i used por-15 and it worked great . i removed the rear diff , gas tank ,exhaust , and repaired the frame . then por15 ed everything , sent the rear diff to be sandblasted and por15 that too .
went from this

to this

 

[gannonrt]

I spoke to the POR-15 tech support last week prior to ordering my starter pack (the Marine Clean degreaser, Prep & Ready, and the POR-15). I have rust in a few different places on the frame or underside of the body but nothing abnormal. The tech support person said they could only guarantee good performance of the POR-15 on the unpainted sections that I'm treating, not the parts where the POR-15 is going over the frame paint. Does anyone have any long term experience with how the POR-15 does after being applied over the frame paint?

 

[afg10000]

Ironically, I just got back from the auto paint supply with bucket of POR-15 ($36). Gonna prep and seal my new Savage sliders this weekend. Gonna top coat with my Rustoleum hi-temp outdoor grill paint (That's what's on my wheels). I know it's not the best, but it's cheap and easy to touch up. Thanks for the tip on the conventional brushes vs. foam brushes. Also, on they're company website they have "directions for people that don't read directions". There's definitely some interesting tidbits in there -

 

[Nelsonmd]

I spoke to the POR-15 tech support last week prior to ordering my starter pack (the Marine Clean degreaser, Prep & Ready, and the POR-15). I have rust in a few different places on the frame or underside of the body but nothing abnormal. The tech support person said they could only guarantee good performance of the POR-15 on the unpainted sections that I'm treating, not the parts where the POR-15 is going over the frame paint. Does anyone have any long term experience with how the POR-15 does after being applied over the frame paint?

It will just peel off like tape. I didn't strip all the original chassis coating off my rear axle, and where I left it, the POR-15 just peeled off in big chunks. I can also confirm that POR-15 will tend to peel off sometimes if it doesn't get good adhesion. I have had this happen quite a bit. Next time I use it, I think I am going to take some very rough sand paper to everything I am painting to make sure it has alot to grab onto.

Even in your hand, the POR-15 that peels off is pretty strong. with good adhesion, I think it is a great product, but i have had some trouble with getting good adhesion. I don't expect any other brand products to be any better though.

 

[Shibby!]

Ironically, I just got back from the auto paint supply with bucket of POR-15 ($36). Gonna prep and seal my new Savage sliders this weekend. Gonna top coat with my Rustoleum hi-temp outdoor grill paint (That's what's on my wheels). I know it's not the best, but it's cheap and easy to touch up. Thanks for the tip on the conventional brushes vs. foam brushes. Also, on they're company website they have "directions for people that don't read directions". There's definitely some interesting tidbits in there -

If I were you, I'd go all three steps. Also, throw them outside for a few weeks or subject them to salt spray to cause surface rusting. POR15 does not adhear well to clean, new metal.

 

[afg10000]

If I were you, I'd go all three steps. Also, throw them outside for a few weeks or subject them to salt spray to cause surface rusting. POR15 does not adhear well to clean, new metal.

Are you serious? I don't mean that in a bad way. They've been sitting in my office for about a month, oxidizing as we speak. I'm gonna scuff them up good before prepping. I'm planning on cleaning with the marine stuff, scuffing, cleaning again, prep and ready stuff, dry then start applying the POR-15 -

 

[00_4runner]

Like I said Rust Bullet.

It works miracles! I'm gonna be doing my entire frame soon. It has ridiculously good adhesion - to EVERYTHING. I used it to prep my CBI rear before I had it line-x'd. I also used it to paint the bare steel where my sliders are welded to the frame. Its been through all of last winter, a midwest winter so plenty of salt, and I see absolutely no rust coming through. And I only used one coat, with minimal prep! Check out their site. Super happy with the product. But good god is it impossible to get off, that ridiculous adhesion I talked about? Stuff stayed on my hands for a week.

Oh and it can be sprayed too. Its how we primed my rear bumper, no dilution needed. Just gotta use a primer tip at I think, 35 psi. Make sure to have plenty of paint thinner around to clean up any spills as soon as possible.

I know its not Por-15 or Osphu but I hope this helps haha.

:rockon:

 

[Shibby!]

Are you serious? I don't mean that in a bad way. They've been sitting in my office for about a month, oxidizing as we speak. I'm gonna scuff them up good before prepping. I'm planning on cleaning with the marine stuff, scuffing, cleaning again, prep and ready stuff, dry then start applying the POR-15 -

Yes.

POR15 makes a mechanical bond with the metal. It "locks" in place and surface rust is the best adhesion for this. That's why rusted axles stay coated the best. Because they have that really pitted, rusted surface.

I've heard of another one that works and it may have been the Rust Bullit mentioned above. My decision hasn't been made yet on my POR15 and Chasis Black coated frame yet. It's holding up ok now, but I expect it to last 5-10 years, which I have my doubts.