In my experience with it, it only works on VERY porous rusted metal, but works very well on that and can be topcoated. You have to topcoat it when it is still tacky. If you put it on new steel or clean steel, it will peel I don't care how much prep you do. It is the chemical bond with RUST that makes it work. Great for inside of surface rusted rockers, doors, frame rails etc. if you are just trying to prolong the life of very pitted metal. Wire brush, paint it on, done. I have put it on rusty parts years ago and it is still there...
