After dry brushing we are asked to experiment with lifting veins. In this case, we are to apply clean water to lift and separate the pigment. I've done a bit of this where after applying water, one gets in with a tissue and mops it all up. See, in that case one picks up the pigment. Here the pigment remains, pushed to the sides.
It helps a good deal to catch the paper at just the right state of dampness. Too wet and the veins spread, too dry and one must work repeatably and only gain a lesser effect.
I think what I most liked was the effect created with parallel veining. I think it will well simulate the monocots like the grasses and those lilies that are challenging me.