Testing the Saunderson multi-layer glaze stack

A single Kubelka-Munk layer isn't enough to capture internal light bounces inside the pigment pool. I built a 659-line experimental lab to compare our baseline Kubelka-Munk output against a full Saunderson 3-layer glaze matrix. The goal was to accurately render the Fuchidori (coffee-ring borders) and refractive-index matching wet-darkening. Factoring in Fresnel internal reflections proved computationally heavy, but the optical depth it adds to the drying decay of the watercolor pools is unmistakable.