proteins on PVDF can be stained with Coomassie-blue (Ponceau
S will not work)! Simply use your gel stain- and
destain-solutions. Unfortunately, I don't know how good it
can be destained and if remaining blue color will interfere
with your following detection (for example in Westerns). If
you want to make Westerns and you use an ECL-system,
remaining blue color will be no problem for you.
Alternatively, use amido-black.
Give it a try, hope this will help you