Trying to find out if there is any adhesion problem with Body filler over the phosphate coating after metal has been scuffed up & Pre cleaned. Bottle says the phosphate coating promotes adhesion & some of the messages say scuff everything over again. I have countless hrs in the complete bottom & wheel wells of a 57 Chevy I am building & used the Fast Etch on all metal To prevent rust & help adhesion but hate the idea of having to scuff everything a second time. Underside will be shot with 3m Body Schutz & wheel wells will probably be painted. Any info would be appreciated.