Red and White Cotton Rosemallow is a pair of silk paintings made by Southern Song (1127-1279) court painter Li Di. These paintings depict the passage of time and life's dynamism through the portrayal of changes that "drunk cotton roses" undergo in a single day. What's special about the silk canvas used for this painting? What kind of pigments did the painter use? Maromitsu Tsukamoto, professor at the University of Tokyo, provides insights.