Mostly I like to set up a pitched battle between the brush and the surface. The energy fluxes and rolls between the two and the outcome is often permanent and edible tension. But sometimes I let the geometry of the curved vase have the last say. Sometimes a battle is too tiring or long-winded when all you want to do is let nature assert its authority and remind us how much we didn’t invent or manufacture. So the end of this stroke follows from the structure of the 3D curve it’s written on, like the most obvious corollary of a rigorous proof.