Terra cotta clay soldiers swathed in a riot of bold colors: red and green, purple and yellow. Most of the colors did not survive time or exposure to air that comes with discovery and excavation. In earlier digs, archaeologists watched as the warriors’ colors disintegrated in the dry Xian air. Once exposed, the lacquer underneath the paint began to curl after 15 seconds and flake off in four minutes. New preservation technique is revealing the terra-cotta army’s true colors.