Im not sure. My brother paints cars for a living and I know we used POR15. Was a long time ago and I don't remember if the POR was a primer or the paint. The primer was red and the paint was a gloss black. Total price for the prep material and paint was around 350.00, he painted it for free. With all the rocks, ruts, roots, mud, dirt and so fourth of off roading, within about two years it was getting rubbed and scraped off. I swore I would not spend that much to paint a frame again. The next frame I did, I put bolts, screws and what ever I had to, into the holes on the frame and used bed liner instead of paint. Seemed to be much tougher, but still got rubbed off in spots after a few years, but I just touched it up where it needed it with paint or undercoat. neither frame seemed to rust any though. I owned the frame that was POR15ed for around 12 years and the other for just a few years before getting rid of them. So, I don't really know which way is best but the sandblasting, POR15 route seemed awful expensive compared to the bed liner and seemed to yield about the same results. I used bed liner on the jeep I have now and painted over it, its the one in my avatar, been a couple years now and it seems to be doing ok. No rust, jjust a few chips here and there.