THANKA ART

Thangkas are painted on cotton  or silk. The most common is a loosely woven cotton produced in widths from 40 to 58 centimeters (16 - 23 inches). While some variations do exist,
thangkas wider than 45 centimeters (17 or 18 inches) frequently have seams in the support. The paint consists of pigments  in a water soluble medium. Both mineral and organic pigments are used,
tempered with a herb and glue solution. In Western terminology, this is a distemper technique.
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The composition of a thangka, as with the majority of Buddhist art, is highly geometric. Arms, legs, eyes, nostrils, ears, and various ritual implements are all laid out on a systematic grid of angles and intersecting lines.
A skilled thangka artist will generally select from a variety of predesigned items to include in the composition, ranging from alms bowls and animals, to the shape, size, and angle of a figure's eyes, nose, and lips. The process seems very methodical,
but often requires deep understanding of the symbolism involved to capture the spirit of it.

Thangka often overflow with symbolism and allusion. Because the art is explicitly religious, all symbols and allusions must be in accordance with strict guidelines laid out in buddhist scripture.
The artist must be properly trained and have sufficient religious understanding, knowledge, and background to create an accurate and appropriate thangka. Lipton and Ragnubs clarify this in Treasures of Tibetan Art:

“Tibetan art exemplifies the nirmanakaya, the physical body of Buddha, and also the qualities of the Buddha, perhaps in the form of a deity.
Art objects, therefore, must follow rules specified in the Buddhist scriptures regarding proportions, shape, color, stance, hand positions, and attributes in order to personify correctly the Buddha or Deities.”