I've Heard of Painting between the lines but, can this be done?
On the deck lid of our '68 Charger we turned it upside-down and after cleaning everything the best we could, we poured POR-15 onto the areas that were sandwiching inner and outer structure. Then we took an air wand and used compressed air to force the POR-15 into all of the crevices.
The biggest concern was wondering whether or not we'd get proper adhesion on areas that we were unable to prep so we did our best to force the POR-15 prep cleaners and etchers through it first. Each chemical was forced with air into all of the nooks and crannies. Then after giving them adequate time to do their work we dried it (between each) with prolonged use of more compressed air.
Only time will tell if it keeps rust away. The car sat for a couple of years after we did this and so far everything we coated seems good. The car was unpainted and the only new rust (surface) was on areas we had not used the POR-15.
My advice to you is to try the best you can to reach as much of the areas you can with the prep chemicals before encapsulating it. We did notice adhesion problems elsewhere on panels that we had not properly prepped.
