Excerpted from Sacred Visions: Early Paintings from Central Tibet,
by Steven M. Kossak and Jane Casey Singer, with an essay by Robert Bruce-Gardner
Copyright 1998 by The Metropolitan Museum of Art, New York. Reprinted by permission
The ground, the predominantly white surface to which the drawing and painting were applied, also had its governing variants and limitations. Com-posed of a light-colored, inert substance - usually chalk or a claylike substance such as kaolin - and bound with an animal glue, it could be more or less absorbent - depending on the dilution of the sizing mixture and the degree of polish - and provide a smooth or an uneven surface, depending on its thick-ness and the weave of the support.
In current practice, which is, presumably, still traditional in this respect, a relatively small amount of warm, liquid glue is added to the powdery inert material, which is then mixed and kneaded in the hand like dough to ensure the even distribution of glue and the elimination of lumps of unbound dry material. More glue is added and stirred in a Container until the correct balance and consistency have been achieved. It is critically important to assess the correct proportion and strength so that the dried ground is neither too loosely bound - and thus too absorbent and friable - nor so over bound that it becomes brittle and inflexible. The desired surface quality dictates the ratio and possibly the selection of the inert material. Kaolin, for instance, might have provided a more compressible surface, one capable of accepting a greater degree of burnishing and polish, and thus greater smoothness.
The ground mixture sometimes includes a tinting pigment to soften a strident white. The mixture is applied to both sides of the support, thus filling the interstices and incorporating the fibers of the threads, and so providing an integrated and secure bond. This seal protects the woven support from the natural agencies of deterioration and of potential embrittlement. After completion of the painting, when it was cut from its strainer, the support was never - unlike Western paintings on canvas - under biaxial tension, which helps to explain the retention of remarkable flexibility. The degree of absorbency of the ground can affect the fluidity and continuity of the brushstroke, so to achieve fine line and detail, a smooth and even surface must be provided; the refinement is in the polishing, or burnishing, of the ground. This ultimate intimacy of weave and ground is the key to the painting's survival, which is superbly illustrated in the suppleness and pristine condition of the Mandala of the Six Chakravartins.