works well. gets all chalky if exposed to sunlight though. if you plan on putting primer or paint over it make sure to read directions first. there is a specific process to do so. also do not get it on your skin. it has to come off over time once dry. won't wash off your skin..
it works wonders on floor boards and such. I bought an older Mustang that had it applied to the floors and lower door shells and they were completely rust free 30 years after the factory put them together.
If you are planning to do any other work on the places you apply it, I'd recommend doing it first-- that stuff is really tough to remove when you need to weld something.
It didn't hold up well to heat for me. Also works best on surface rust, or metal etched first. I have it on my front rear bumpers and the rock rails. Oversprayed with rustoleum hammered. The rustoleum will chip off but the por-15 usually stays in tact underneath
I've used this stuff for years and years. If it's applied correctly, I haven't found anything better. Just make sure you get the full kit that includes the Marine Clean and the Metal Etch. If you thin it, use POR15's reducer. The best way to apply it is to brush on POR15's original formula; then scuff and apply their Chassis Coat Black for UV protection and gloss selection. Combined, that product is tough as nails!
If you plan on spraying it, make sure to wear a full bunny suit and have a full face fresh-air respirator outside of your spraying area. POR15 contains Isocyanates that can be absorbed through the skin and tear ducts. Not only that, but if you inhale enough of it, it will literally kill your lungs quickly.
A quick health advistory about paints with Isocyanates: :soapbox:
I used to paint with a guy that had 40+ years in the business and by the time he retired (at 60) he was on 24/7 oxygen and daily Nebulizor treatments. The hardeners they used to use in Alkyd Enamels back in the day use to contain Isocyanates. In the 70's they would just use disposable masks or half-masks. That stuff is SO dangerous. Always use a rebreather, or pressurized fresh air breather.
If you don't have the neccessary equipment to spray it, just brush on the POR.
x2 on POR-15. Of course as mentioned by others, its only as good as the work you put into the prepping of the application
1. clean, clean, clean the metal to be painted
2. clean it some more
3. etch it
4. apply in multiple THIN coats
5. when slight finger drag, apply additional coat
6. when final coat is almost dry (very slight finger drag), apply topcoat
7. I use rustoleum as a topcoat to prevent the "chalking out"
I've used it and it's great. I mainly bought it to use on part of the rear floor pan and under the battery tray in my XJ, and parts of the unibody underneath my Mustang. I had some areas that were pretty significantly rusted and wanted a product that would not only prevent rust from coming back, but also help reinforce areas where the metal was thin or pitted. It did exactly what I was hoping for, it cures super hard and you can apply it much thicker than paint, especially if you do multiple coats (I think I did two). I'd definitely buy it again.
These guys are right, following the instructions precisely and doing the right prep work is important if you want the best results. I used POR-15's Marine Clean and Metal Ready products as recomended before applying the POR-15 itself. I wasn't sure if they were really necessary so I actually called the company up, they were very helpful and explained that while you don't have to use them, you will get much better results if you do. The Marine Clean gets the metal perfectly clean of any grease or residue and doesn't leave anything behind, more so than other degreasers apparently (it is one hell of a degreaser); and the Metal Ready etches the surface to give the POR-15 something to stick to. You can skip the Metal Ready when applying POR-15 to already rusted surfaces (although it doesn't hurt to use it) but they say it is absolutely crucial to use it on virgin metal. In my case I had removed the loose rust using a wire wheel on a drill, which also took paint off of the surrounding areas, so I used it. It's a bit of an investment to buy all three products, I think I spent about $65, but they go a surprisingly long way. I have plenty left for future projects so it was totally worth it IMO.
Buy good rubber gloves, have some rags handy, and wear clothes you don't care about (shoes too), because this stuff does NOT come off. If it gets on your skin you'll probably be wearing it for a couple weeks. I did my floor pan almost two years ago and I still have a quarter sized black spot in my driveway where I dripped some on the ground. I had dripped some onto my muffler from an open drain plug hole and it was still on there when I replaced it a year later.
Also worth knowing is that if you get POR-15 around the edge of the can it comes in and close it up like that, it will seal the lid to the can and you'll never get it open again. If you don't close it up completely air tight it will cure and you won't have any more usable product. Since I bought the smallest can they sell, I use a tablespoon to dispense it into a separate container to brush it on from, and then close up the can immediately. I haven't opened it in couple months but it seems to have a pretty long shelf life as long as it stays closed up air tight.