Detail of the wall paintings in Cave 85 of the Mogao grottoes, where the GCI is collaborating with the Dunhuang Academy on a wall paintings conservation project. The rock temples of Mogao were created by carving into the soft conglomerate rock cliff face and plastering the walls with a mixture of local clay, sand, and hemp fibers. To prepare the surface for painting, a second layer of finer clay plaster was applied, and over this, a thin white colored ground was added. Line drawings were made over the ground to outline the figures; mineral and organic colors were added later. Photo: Francesca Piqué.