Not to start a rust treatment war here, but there's several things wrong with what's been said here.
First, POR 15 is not dangerous if properly handled. I have painted it on my frame using brushes and gotten it on my skin with no ill effects. Brush painting doesn't create a lot of vapors, so normal air circulation is enough to ventilate the work area. Also, I had no problem with brush strokes as one person indicated.
Second, POR 15 can be spray painted. Just follow the directions, use proper ventilation and mix it according to the directions.
Third, the POR 15 vs. Zero Rust comparison at autobodystore.com has a fatal flaw. He used a #24 disc to grind the metal. POR 15 specifically states that you do not want shiny metal, and if you sandblast or otherwise smooth the surface first, you will not get good adhesion. One of the nice things about POR 15 is it requires little or no preparation.
The key to using any product is to know how it's supposed to be used.
Zero Rust will chip if struck. POR 15 will not. So, I chose POR 15 for my frame and undercarriage because I don't want to be constantly crawling under there recoating chipped areas.
Both products are good. You just have to use them according to the directions.
