View this artwork by appointment, at Tate Britain's Prints and Drawings Rooms
These two sketches consist mainly of lines drawn with a soft graphite pencil. The buildings have then been heightened with white gouache applied with a brush. To the naked eye, the white pigments look the same. However, ultraviolet examination revealed that Lewis used zinc white for the upper sketch and lead white for the other. At this time, zinc white was not commercially available to artists (Winsor & Newton introduced it in 1834), which shows Lewis's interest in experimenting with new materials. It is also interesting that Lewis used both white pigments within the same sketchbook.
Gallery label, September 2004