Wednesday, August 29, 2012

POR15 - the truth

There is still a lot of block sanding and bodywork to do on the car before it is ready for paint....and the hood, deck lid and fenders haven't even been started yet....but lately I have been ignoring these issues entirely and enjoying this view of my car again:

What I have been doing is working on restoring some more of the smaller parts that I will (one day) use to rebuild the car. I started by examining some of the parts I restored about a year ago. I used POR-15 to paint the rear axle housing and some of the brake parts, and I also used it on a few other the door hinge mounting plates, and the brackets that go behind the rear valance. Inspection of these items showed evidence of bubbling at the paint surface, although it wasn't all that bad....

But when I checked out the leaf spring locator plates, it was worse: actual rust inside the bolt hole!

On the rear bumper internal brackets there was a huge bubble in the paint and an area where it had peeled off

When I skimmed over the surface with the wire wheel, I found the underlying metal thick with rust - it certainly wasn't like this when I painted over it!  

So what's all this then? Well, I was sceptical about POR-15 even when I originally used it on the rear end, because I've heard so many people, both personal friends and on the net, saying that it peels right back off. However, the manufacturers general response to this seems to be that it only peels off if you get water into the product....or in other words, if it peels off, you mixed it wrong. OK, so I have a past life as an organometallic* chemist (can I admit that here?), so I understand exactly what it means to exclude air (and thereby water vapor) at the parts-per-billion level....and I'm confident I did more than enough when I used the POR-15. And it still peeled off. And not just on one part, but on most of the stuff I painted. So I rest my case as this: "POR-15 is rubbish. It's worse than useless in fact."  I'm not claiming I'm the first person to say this (lol, probably not in the first 100,000!) but I'm adding my voice :)

(*Next time out I'll be reporting my own experiences on the chelation approach to rust removal so watch this space)


  1. That is a huge let-down to be sure. What I don't understand, is they (POR-15) claim that atmospheric moisture is REQUIRED to properly cure the coating. With a cleaned substrate like you had, it would seem the coating integrity should be perfect! I think your experiences just solidified my intent to treat a few hard-to-access areas with rust conversion coatings and prime with DP-40.

    In any case, I am lookinmg forward to your chelation trials. I have used it extensively and am quite pleased. All the best!

  2. Well, Ian, you've convinced me not to use it. I was thinking about it for the cowl hats to keep them from rusting but no more. The question is this: Is there anything out there that's better than POR-15 that will work? I'm all ears.

  3. Ah man. Sorry about your POR-15 troubles. On the other hand, I haven't had any similar issues with ZeroRust... Yeah, it's not as pretty as POR-15 but it's a true rust encapsulator that was developed for marine environment use... protecting nasty, rusty, ship hulls in a saline environment in other words. Just sayin' :-)

    Can't wait for your Chelation tests though!

  4. I'm using Rust Encapsulator from Eastwood. It is still a bit too early to tell but I hope it works better than POR-15. Now I'm glad I did not spend the money on POR-15.

  5. Joy, in my experience, for small parts like this, you just can't beat powder coating. I had similar experience with these 'rust preventors'. I finally bought a small bead blaster and powder coat kit - built a powder coat station from plywood - found a junk kitchen oven - and never looked back. If I ever find a way to fit the chassis in the oven, it's going to get powder coated too!!!!

  6. Thanks to everyone for your comments. I should probably say that I only used POR-15 on a few items because I had heard a lot of bad press from the guys in fact the places where I did use it were really just "proof of concept" pieces before I got properly stuck in...or not as the case turned out :)

  7. My experience with POR-15 was good but I had to prep the metal very well. Then over time I either replaced the metal or media blast the parts. Rust is rust, it's never going to go away unless you remove it completely. The only thing you can do is to prevent it from happening on your new parts.