I'll relate my experience with the Vallejo "Still Water". My first experiments with this stuff were mixed. One experiment ruined a base. When I decided to use it on my swamp project, my experiments showed that for a thin layer like this I was better off trying it without a dam around the base. The viscocity of the stuff allows it to bead up quite a bit before it will run over. If you apply to something that has very little tooth it will bead up unless it's in sufficient quantity to create a "pool".
My project went like this;
Spray paint the swamp area green
Finish of with oils to create various greens, shadow areas under the figure, and water lilies
Install reeds using gel medium'
mount figure using gloss medium mixed with a dark green acrylic
pour on "Still Water" usher into place using a brush
Ripples were an accident that happened when I attempted to pull the "water" away from the figure as it stared to climb up the torso.
