Page 87 - Tibetan Thangka Painting Methodsand Mat, Jackson

Monks grinding white mineral on a stone mortar.

and replaced with fresh water. When the water stopped up of chalk plus gypsum. 42 Gypsum is a mineral form
yellowing the mineral could be ground, and again soaked of calcium sulfate that has been used to make white
in water. The need for preliminary soaking, combined paints in many parts of the world since very early times.
with its greater hardness while grinding, made the The use of synthetic whites such as lead white and
masculine type more work to prepare, but when finally zinc white in Tibetan thangkas was not mentioned by
rendered into a usable pigment it could not be distin- our informants. Nevertheless, by the beginning of the
guished from the feminine variety. present century small quantities of lead white in
Ka rag was ground dry, and then after that even particular must have been coming into Tibet from India
the feminine rna rag had to be soaked in water to leach or China. 43
out yellowing impurities. When the pigment had been
well ground, the artist might test it, by putting a small
drop on his tongue and then feeling for any undesirable Carbon Black (snag tsha)
granularity by rubbing it with his tongue against the
roof of his mouth. After final grinding and soaking, The blacks used as paints in Tibet were made from
ordinary earth whites as well as cheaper earth pigments carbonaceous materials, and the sources - soot and
were commonly transferred to earthenware pots, which black ash - were common almost everywhere in one
through absorption and evaporation speeded up the form or another. Since carbon is chemically very inert,
extraction of water from the wet pigments. By contrast, it was the basis for permanent, excellent pigments.
Tibetan painters always stored their expensive pigments Soots and black ash were produced by heating a
in non-porous containers. substance such as wood or oil without causing its
In addition to ka rag, painters in some regions of complete combustion. The most common way of
Tibet occasionally used other calcium compounds for making soot for pigment use was to burn the chosen
their white. Eastern Tibetan artists, for instance, material slowly and imperfectly; such a fire produced
described a white pigment that they used to make by smoke that consisted of millions of minute black
calcining animal bones. This too was a calcium white particles of ash. These tiny particles needed only to be
since the main constituent of bone ash is calcium phos- retrieved to form the basis for a black ink or paint.
phate. Similar bone-ash whites were used in medieval Tibetans knew the age-old process for making ink
European painting. Finally, the analysis of the pigments (snag tsha) from soot and glue. Mi-pham-rgya-mtsho, for
of one "Nepalo-Tibetan, late 15th or 16th-century" instance, gave the following description of ink manu-
thangka revealed the presence of a white pigment made facture:

MINERAL COLOURS 83