The most common is a loosely woven cotton produced in widths from 40 to 58 cm (16 - 23 inches). While some variations do exist, tangkas wider than 45 cm (17 or 18 inches) frequently have seams in the support. The paint consists of pigments in a water-soluble medium of animal glue. Both mineral and organic pigments are used. In Western terminology, this is a distemper technique; although it is often described as a form of gouache, this is incorrect, and the paint was applied as a warm liquid, mixed shortly before application. In Nepal, 24 carat gold is also plated over some parts of Thangkas painting which makes the art a little more expensive. Most old thangka have inscriptions on the back, usually the mantra of the deity depicted, but sometimes also information as to later owners, though rarely information about the original commissioner or artist. Sometimes x-rays allow pious inscriptions placed under the paint on the front of the image to be seen. Inscriptions may be made in the shape of a stupa, or sometimes other shapes. 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: "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." Nepal The earliest surviving thangka paintings from Nepal date to about the 14th century AD, but this is probably well after Buddhists and Hindus