Looking for Alchemist....???

[Hogshooter]

Your plan of the DP 90 is probably better than weld thru primer, since it is only designed for mating flanges. I would blast and apply several coats of DP then weld what you need to and use the wands. I have a freind who uses a pump-up garden sprayer with a piece of stiff plastic tubing to extend the tip which he reuses, it allows him to spray 360* and is cheap. I have a kit with the wands and a gun which works best. Again I would not worry about the weld through if you are going to use epoxy. I coat rockers with epoxy then use 3m Rustfighter I, this is a wax based liquid that helps to flow inside and seal minor crevises I use it in doors and quartes also.