Just to second a previous comment, POR-15 has worded very well for me. I saw a test in Auto Restorer's (?) Magazine, who were as skeptical as I was. They used it (along with some fiberglass matt) on a floor section lacey with rust as a last shot before cutting and welding on a vehicle meant to be a driver. They were amazed afterward that they could bounce on the lacy floor after the POR-15 dried.
I used it on supports on used running boards for my F150 - just wire-brushed the surface rust and applied POR-15 - and it was still shiny with no rust pop-through 3 years later when I sold the truck. I like to prime while the POR-15 is still tacky, beause it dries shiney and is extremely difficult to rough up to offer adhesion for later paint; hard even to scratch with a nail. And, because it is not UV resistant, it should generally be painted. I had a trailer on which I used just POR-15 have the surface deteriorate over 4 years, while the supports under the truck and a brake vacuum booster held up well not exposed to sunlight.
Read the label and follow the warnings. If you close the can without plastic wrap under the cover, you will NOT reopen the can short of destruction. If you keep dipping a brush in the can instead of pouring out what you need, or if you pour left-overs back in the can, the whole can will solidify - looks neat but not useful. Also, I recommend gloves and clothing about which you care little or not at all.