“I think Murnau’s imperturbable calm in the studio was due not only to a sense of discipline, but also because he possessed that passion for ‘play’ itself which is necessary and essential to any kind of artistic activity.
For instance, I’d made a steam apparatus for the heaven scene in the Prologue to Faust. Steam was ejected out of several pipes against a background of clouds; arc-lights arranged in a circle lit up the steam to look like rays of light. The archangel was supposed to stand in front and raise his flaming sword. We did it several times, and each time it was perfectly all right, but Murnau was so caught up in the pleasure of doing it that he forgot all about time. The steam had to keep on billowing through the beams of light until the archangel — Werner Fuetterer — was so exhausted he could no longer lift his sword. When Murnau realized what had happened, he shook his head and laughed at himself, then gave everyone a break.”
-Faust art director Robert Herlth, quoted in Lotte Eisner’s Murnau. The scene Herlth is discussing is online here.
Camilla Horn in F.W. Murnau’s Faust, 1926