The questions most frequently asked of us while working on the Buddhist murals in the Chinese rotunda involve what the murals are made of. Often people presume they are frescoes. True fresco is done on wet plaster. The pigments used in a fresco are mixed with water and applied to a wet plaster surface. A binding agent (the liquid gel in which pigment is carried) is not required; the pigments are absorbed by the wet plaster and they dry and harden as a single layer. The Buddhist murals are painted on a mud surface and follow a basic mud-ground-paint construction pattern. They have several distinct layers, thus they are quite different from a fresco.
There are two different mud layers under these Buddhist murals. The first (closest to the wall on which the mural was painted) layer is a thicker, coarse layer with large and frequent straw and seed inclusions. The second is a smoother, more homogenous mud (lacking the visible pieces of organic material present in the coarse layer) and it is less than a centimeter thick. Due to the deterioration and loss the murals have suffered over time, these two mud layers are visible and easily differentiated along the bottom of both murals.
A ground layer, probably kaolin (a fine white clay), was applied over the mud surface. The ground is a bright, pure white color that created a “blank canvas” effect onto which the colored pigments were applied. The ground layer provides a smooth, white, level surface for the paint.
There is a wide variety of colors used on both murals. The paints used are made of pigments and a binding medium. The pigments themselves are probably mostly mineral based while the binding medium is likely organic. Identification of aged organic materials is difficult under the best of circumstances and we are not optimistic that we will be to determine what specific binding medium was used. We will be conducting analysis on the types of pigments used within the next few weeks, so check back in for those results. If you look closely at the colored robes of the Buddha, Bodhisattvas, and attendants, you can see carefully and delicately shaded areas indicating folds and creases. These and many other details in the compositions were achieved by using multiple layers of paint over one another in order to achieve depth.
When the murals were taken off of the monastery walls, they were assembled into larger panels and backed with plaster and wood for support. These larger panels are the separate segments visible today. The panels were assembled and installed in the Chinese rotunda in the 1920s. There is no documentation illustrating how they were installed or what supports are behind them. As part of our analysis we are trying to outline the framework behind the murals.
The Buddhist murals, in their current condition, appear to be held in a wooden scaffolding type framework against the rotunda walls. The panels are comprised of modern and ancient layers as illustrated in the cross-section above. The wood and plaster are modern supports; the mud layers,ground, and paint are original; and we are slowly uncovering the metal framework behind each panel by means of metal detection. We’ll be posting about that process later so stay tuned for it as well!
Acknowledgements: Work on the Buddhist Mural Conservation Survey in supported by the E. Rhodes and Leona B. Carpenter Foundation and Michael Feng and Winnie Chin Feng.