Page 85 - Tibetan Thangka Painting Methodsand Mat, Jackson

The pigment was believed to have the peculiar property Several techniques exist for the production of
of becoming a lighter red if ground with circular move- minium. A recent process used in the West involves
ments, or a darker red if ground with strong up-and- heating lead in contact with air. The molten lead first
down pounding motions. According to one painter, to becomes oxidized into litharge (lead monoxide, PbO),
0
get the pure, intense scarlet, both the up-and-down and and then if heated continuously at 480 C it converts
32
the circular motions had to be employed equally. The to minium. Similarly, colour makers in India prepared
pigment was ground in that way slowly and gently, minium by roasting white lead, the basic carbonate of
mixed with a little water. The Chinese vermilion makers lead, in the open air, First it became massicot, a lead
by contrast typically ground their cinnabar without any monoxide similar to litharge, and finally it converted
pounding or circular grinding at all: traditionally they to the orange tetraoxide, minium. 33 In China, on the
pulverized the vermilion in a large boat-shaped other hand, a somewhat different technique was used.
receptacle by means of an iron roller. 28 According to an old Chinese materia medica minium
In Tibetan painting the highest quality vermilion was produced by adding vinegar, niter and sulfur to
was a brilliant scarlet. Some grades of vermilion, molten lead. Another method mentioned in this Chinese
although chemically pure, became a muted maroonish text entailed the roasting of the residue left behind from
red when mixed with size and applied to the canvas, and white lead manufacture together with some niter and
3
so were not valued as highly. Vermilion was sometimes alum, 4 These Chinese processes produced not only
adulterated with cheaper red colouring matter, which mmlUm, but also impurities such as sulfates of
could often be detected by mixing a little pigment with potassium, lead and aluminum.
water in the palm of the hand and then rinsing with In Sanskrit the pigment minium is usually called
water. Dyeing impurities left a red mark on the palm. sindhura. Consequently, one finds that Tibetan authori-
In such cases rinsing the pigment in water would ties such as Mkhyen-brtse lo-tsa-ba give the term
improve the colour. In Tibetan me'dicine too the brighter "sindhura" as a synonym of li-khri (the ordinary Tibetan
shades were considered best, and texts on medicine term for minium).3S But other Tibetan writers, such as
likewise recommended repeated washings to improve the influential Dil-dmar dge-bshes, state emphatically
the "dark vermilions" (mtshal nag). 29 The Chinese in that li-khri and sindhura are distinct substances,
particular were masters at producing the most highly According to the latter group of writers, real sindhura
prized, intensely brilliant shades of vermilion. was like minium except that it was a little bit darker
and browner, and it was also said to occur on lake
Minium Orange (li khri) shores and in rock cavities in special locales. 36 Perhap~
the term sindhura was used by the latter writers to mean
native litharge (yellow lead monoxide), or mixed
litharge and native minium deposits, which sometimes
occur on weathered lead-bearing ores.
Tibetan painters judged the purity of their minium
by its weight, colour and texture. The best, purest
qualities were extremely heavy, intensely orange, and
not sandy but smooth to the touch. The pure powder
squeaked when rubbed between the fingers. These
characteristics could not be duplicated by any other
pigment, but the purity of minium might be tampered
with. When an artist had to work with qualities other
than the best he could usually wash outmost of the
impurities by repeated rinsings. Minium seldom required
For their main orange pigment, Tibetan painters used any grinding; if it was pure, only the addition of hide
minium, the synthetic tetraoxide of lead, Pb 0 . This
3 4 glue was needed to prepare it as a paint.
pigment is also known as "red lead," but the varieties
used by Tibetan painters were actually intense orange, Orpiment Yellow (ba bla) and Realgar (ldong ros)
and not red or scarlet. Tibet did not produce its own
minium, but imported it from Nepal and China. Minium
was also produced in India; the author of one Tibetan
materia medica mentioned varieties of Indian minium
that were produced from earth, stone and plants. 3D But
the writers of such texts were also aware that the
miniurns of China and Nepal were made from lead, in
spite of the fact that they classified these as "naturally
occurring earth medicines" (rang 'byung ba'i sa
sman). 31 For painting in particular, our main infor-
mants considered the synthetic miniums of Nepal to be
the best.

MINERAL COLOURS 81