Couple of POR-15 questions

one other thing , at least on my car , I am not completely stripping all the origional paint from the engine bay. Some rust repair was done in the battery area and was treated with the por systime . The entire engine bay was mariene cleaned after a sand blast and was also treated with metal ready. POR was applied to any bare metal however the painted surfaces were treated with the chemicals . Now It was recommended that this should be done to the painted surfaces before any por finish was applied. I am now top coating everything with tie-coat primer. in preperation for a complete paint job. The reason given is the mariene clean will leave a residue that the metal ready will nutralise sp the chemical.