POR 15 is more like a paint. I used it on my front beam once I removed the nose. I sanded and cleaned the surface and covered with POR 15. If you have severe corrosion, POR 15 isn't like a glue to hold parts together.
Por-15 goes a long way, I bought a pint off amazon for under 30 bucks last year and it was enough to cover my entire cradle with 2 coats, the entire floor in the interior, and other stuff as well. And I still have a bunch more left. It self levels great and is easy to apply. I recommend it because I had a brake line burst in the rear, covered a whole bunch of my engine, chassis, and cradle with brake fluid. The cradle had been top coated with rubberized undercoating. the brake fluid took the paint completely off of my block, the stock paint on the chassis which was in good condition, completely stripped the rubberized undercoating off the cradle, and did absolutely nothing to the por-15. Rust breaks through layers of paint often when using pretty much anything else that air dries (in my experience) after maybe a year. I am going on 2 years with the POR and have taken the car in a salty slushy massachusetts winter driving it almost every day, no matter how much snow or slush is on the road. the POR holds up like a champ. I even dropped wrenches on the cradle a couple times and it does not chip the paint at all, it is some really tough stuff.
It just does not like to be applied to clean bare metal without a special prep spray. It covers up unevenness lost from rust really well. The best way to rust proof in my opinion is to strip everything and spray with a quality epoxy based paint, but that is expensive. POR is a great way to not do that much work and have something that will look good and last a long long time
I have had good luck resealing the can with a plastic shopping bag between the lid and can, it makes it easy to reopen, and when you peel off the shopping bag over the top the paint is nice and fresh underneath. I would replace the shopping bag each time you open and close it.
If you are dealing with deep rust, a product like por15 is good when the work is done and you are rust free.
The problem with deep rust is that even when you sandblast the surface clean, there is still oxidizing in the pores of the metal at a molecular level
After you weld in new metal, you are better off with a rust inhibitor on the repair. What I have had allot of success with is yellow Tremclad as a primer on repaired rust work. It is the same stuff used on heavy equipment and it will inhibit further rust. If you coat over top of it with some black stuff like Por15 you should have a good job. If you don't use a rust inhibitor though, you are just delaying the inevitable Hope this helps
POR works well, but you can buy similar items at your local NAPA, sometimes.
Agree but sandblasting will eat the rust and steel as well so you might just end up with a lot thinner peace of steel after sandblasting. hit it with a welders chipping hammer after you are done to make sure it is still metal and not tinfoil.
------------------ Technology is great when it works, and one big pain in the ass when it doesn't