I wanted to paint the non visible areas with por15. These areas have a lot of surface rust so I am going to get rid of as much as I can with sanding, naval jelly,etc. Lastly I am going to prep with Jasco brand metal (rust conveter) prep/primer before the por15. Do you guys know if the por15 will stick with this metal prep? Or do I need to use some type of etch primer before the por15 for the areas that are clean(no rust) metal?