Watercolor effects on partially wet surface are demonstrated in this easy-to-follow video.
In this demo I first wet my surface and let it sit for a moment. Afterwards I dry the surface partially (almost haphazardly) with my hair drier.
This results in uneven wetness. A paper “primed” this way assures a variation of edges – and a level of unpredictability! And the painting process at once becomes more fun and surprising!
I only work with two colors, Ivory black and Cobalt blue.
While not necessarily desirable, the unpredictability factor can help you understand how to react (and not react!) to watercolor’s natural fluidity.