When I was conservator at the Rijksmuseum from 2017 to 2019, I studied the Indian drawings in the collection. I was fortunate to benefit from the great expertise of Robert Erdmann, senior scientist at the Rijksmuseum in Amsterdam and professor at the University of Amsterdam, who developed the ”curtain viewer”, a web-based image viewing technology . The method is mainly used for painting on canvas, but can also be successfully applied to tempera and works painted on paper. The method involves the following process: the painting must be photographed in high resolution, then scanned by infrared reflectrography, a method that allows the visualization of underlayers made with carbon-based materials (ink, charcoal, pencil, etc.). Then, the two images are processed with the image processing software developed by Robert. As a result, the stitched and registered images allow us to see underneath the layers of paint and reveal fantastic details that are not visible to the naked eye. In addition, they provide insight into the technique and condition of the paint, including degradation phenomena. A few painted folios were processed with the software and put in open-access to the largest audience.
I would want to play with the whole images, they are here
Radha flirting with Krishna, Chamba, 1800, attributed to Chajju RP-T-1993-123. Curtain viewer here (Swipe the mouse accross the work). The infrared reflectography reveals that under the blue painted border, some trial lines were made by the painter as he wiped his brush on the paper to remove any excess paint. The painting is attributed to Chajju, an accomplished artist who belonged to a very well-established family of painters in the Pahari hills. Both the clarity of the drawing, which shows almost no alterations between the underdrawing and the final painting, and the accuracy of the contour lines, indicate that he completely mastered his drawing.
The curtain viewer also confirms that the vasli or a paste-board constituted of laminated repurposed sheets of paper. In a Portrait of Sukhjivan Khan, a ruler from Kashmir during the eighteenth century (RP-T-1992-10), infrared reflectography reveals that a drawing sheet was reused to make the wasli. The underlyingsheet shows an elephant head, a bird with oversized wings, and a sort of magical creature with horse legs and a dragon tail. Curtain viewer here.
In the wrath of Jarasandha at Mathura, Kangra school, 1820, RP-T-1979-3, the curtain viewer allows to see differences between the primary composition in the finished paintings. Check out the birds and the central character’s arm that disappeared in the final version here
The results of the research project were published in: Amélie Couvrat Desvergnes, ‘Indian drawings from the Rijksmuseum: an insight into their production, their purpose and their significance’ in Unexpected fame: Conservation approaches to the preparatory object. Proceedings from the International Conference of the Icon Book & Paper Group, Oxford 1–2 October 2018 (London, The Institute of Conservation: 2020). Here