The water and other reagents (antibodies, stain ...) can't access the surface of the PVDF membrane in case it's not activated by methanol. If you buy a PVDF menbrane (e.g. from Millipore or Amersham) just read the little manual that comes with it, it explains the properties of the membrane very well.
Anyway, even if the membrane was always kept wet, it's still important to activate it again before performing critical steps (and then of course wash away the methanol with PBS ...).
The MemCode comes with all ingredients and a manual. For Ponceau S:
1. 0.1 % (w/w) Ponceau S powder in 5 % acetic acid
2. 0.3 % Ponceau S in 3 % TCA (trichlor-acetic acid).
Both stain equally well. You might want to try both solutions in parallel.
Activate your membrane with mehtanol, wash it well with PBS (or water). Stain it with Ponceau solution (a few minutes) and then destain it with water (put water on the membrane, shake it a couple of times, discard water; repeat until you see the bands well and don't have much background).
With Ponceau staining it's better to scan the blot when still wet (for ducumentation) because the blot usually looks better when wet.
With Memcode you can also dry the membranes after staining because the bands are still visible well when dry.
You can even perform the staining after you already blocked the membrane and made a ECL detection.
Just strip the blot well and stain it. If you want to make another antibody reaction (... ECL), just block again and go on like usually.
A plus, Gerald