Yupo is a unique alternative to traditional watercolor papers. It's an incredibly durable, stain-resistant, non-absorbent synthetic paper that holds ink with razor sharp precision. This extraordinary surface also resists tearing and buckling and it remains perfectly flat. Yupo's ultra white color and super smooth finish makes all the colors of the rainbow sing when applied to this revolutionary surface. Colors are brilliant, and they lift off completely. It is an extremely forgiving sheet! Neutral pH with a smooth surface.