Page 117 - Tibetan Thangka Painting Methodsand Mat, Jackson

comparatively cheap synthetic indigo was developed. Lac Dye (rgya tshos).
This caused severe economic disruption in India where.
huge tracts of land had been used for growing indigo
plants, and nowadays very little of the dyestuff is
naturally produced.

Tibetans used to import their indigo in slabs or
chunks of prepared dye from India and Nepal.! Several
qualities were available. Good qualities were light in
weight and easy to break. The best grades could be
identified by the fact that the new surfaces of freshly
broken indigo would reflect light with a reddish tint.
The authors of Tibetan materia medica similarly state
that for medicine the inferior grades appeared light Lac dye or lac lake is a red dyestuff that is produced
blue, while the best quality had a deep reddish tinge. from resins secreted by the tiny lac insect (Laccifer
Other tests could be used to gauge the quality of lacca), and which is still used in India and neighbouring
indigo. If a little good quality indigo was moistened countries. The lac insect is a species of scale insect, so
and rubbed between the fingers, it dyed them a dark named because the resinous products it excretes are
blue-black that could not be washed off easily. Another deposited in tiny scales on the host trees. Tradition has
test was to scratch a piece across the thumbnail. If the it that the name lac derived from the Persian word lak
indigo left a black streak it was of good quality. A or the Hindustani lakh, meaning "one hundred
variety of light indigo that failed these tests was known thousand", the insect being so named because such an
as he rams. Although it was unsuitable for dark outlining immense number of insects was required to produce a
it was good for making washes for the fine shading of small amount of shellac. Chemically, the dye is laccaic
such things as clouds and flowers. acid or its salts, and it is related to the carminic acid
For preparing indigo in a consistency suitable for derived from cochineal. Lac dye may have been brought
painting the most important thing was to grind it well. from India and introduced to Europe by the Arabs as
Prolonged grinding not only produced a smooth, ink-like early as the 7th century. It became commercially impor-
consistency, but was also said to improve the colour tant in the 17th century when the East India Company
because the longer the dye was ground the darker its exported it, even before shellac (the resinous by-product
blue became. To grind indigo, the artist first crushed of lac) had been introduced into Europe.
it into a powder and then added a little water and Lac dye was sometimes imported into Tibet from
stirred it until it became dough-like in consistency. India in the form of small dry cakes or pellets. Also it is
Then he ground it in a mortar until the once moist said to have been received from China in the form of
dyestuff became almost dry. He then moistened it again, wafers of compacted cotton (srin bal rgya tshos) that
2
and resumed grinding until it dried out again. He had been saturated with the dye and dried. However,
repeated this process of moistening and grinding many most of the lac dye used in Tibet was probably produced
times, and sometimes a single batch of indigo would be from the raw materials by the Tibetans themselves.
ground for two days or longer.
Strictly speaking, indigo did not require any hide Preparation
glue as a binder. The addition of a little glue, however, Tibetans extracted lac dye from crude forms of
was said to facilitate the grinding process. Also, when it lac such as stick-lac (twigs encrusted with lac-insect
had been thoroughly ground its quality as a paint was scales) that they obtained from the warmer border
improved by the presence of a little glue. This was regions of the Eastern Himalayas. Artists could also get
because indigo in solution with water tended to the crude lac in the form of scales already separated
coagulate in the paint pot as it dried out, but this from the twigs of the host tree. If stick-lac had been
drying process was slowed down and the indigo was obtained, the artist first had to scrape off the scales from
held in aqueous suspension longer if mixed with a little the sticks and remove any woody debris from the scales
glue. because heating the lac together with the sticks would
Being a dye, indigo was well suited for both yield an inferior dye.
shading and outlining. In almost every instance where Once he had removed, cleaned and crushed the lac
it appears that ink has been employed for either purpose scales, the dye maker next heated the scales in hot water
in traditional thangkas, in fact it is indigo that has been to melt them and to extract the dye. 3 Care was taken
used. Indigo was superior to Indian and China ink, not to overheat the lac, for this would blacken it and
according to one of our informants, because it was less spoil the whole batch. Also, it was said that the pot used
prone to running and streaking if water was spilled on it. for heating the lac should not be made of copper
One painter also asserted that in an earlier period some because this metal tended to blacken the dye when the
artists used to employ indigo for reinforcing the initial lac was heated. A large porcelain. bowl was said by one
charcoal sketches, instead of the usual ink. painter to be the ideal container.

THE DYES USED IN SHADING 113