Starting in England, around 1780 the spectacular medium of painted transparencies conquered Europe. The Kassel museums hold one large-format work, "Moonlight" by Caspar David Friedrich, painted from both sides. When it is illuminated from behind, the fog on the front clears and a hilly landscape with a distant town appears as if by magic. Friedrich was even able to create a film-like sequence of the passage of time over a day from early morning to deep twilight using historical means of lighting. How does "Moonlight" in Kassel fit into the history of transparency painting? Where did Friedrich learn about this unusual medium, and how did he master the technique to a previously unrivalled perfection? Research into the subject has been very productive. - Fresh insight into the fascinating medium of transparency painting around 1800 Insight into Friedrichs only largeformat transparency, 'Moonlight', and its technique Cooperation with physics historians on historical means of lighting Look inside

Christiane Lukatis has been director of the Graphic Art Collection of Hessen Kassel Heritage since 1996