Generally, frescoes were painted on the surface of walls of granite or laterite after they have been prepared suitably. The wall, technically referred to as the carrier, was first given a rough plaster coating, with a mixture of sand and lime. A second, smoother coating of plaster was then applied on the first. These two layers [are] technically referred to as the ground. A mixture of resin and lime solution was used as the binding medium for dyes.
The frescoes of Kerala belong to a class known as fresco-seco, characterized by its lime-medium technique. The frescoes of Kerala, like those of Kancheepuram and Sittanavasal belong to this variety. Here, the murals are painted only after the prepared wall is completely dry. There is another category of murals called the fresco-buona, in which the color pigments are applied on a partially wet plaster ground.
Vishnu Dharmottara Purana (4th or 5th century A.D.), Abhilashitartha Chintamani (12th century A.D.) and Silparatna (16th century A.D.) are the three principal texts dealing with Indian painting techniques. These three tests are agreed to a large extent on the four different phases for the completion of a wall painting:
- Preparation of the ground
- Sketching the outline
- Application of colors, and lastly
- Addition of decorative details.
The Chitralakshana section of Srikumaras Silparatna had a direct bearing on the style and techniques of Kerala murals. This section dwells at length on the various aspects of painting like its definition, suitable themes, the preparation and application of plaster on the wall, the names of primary colors, how to prepare the plastered surface, how to sketch the outlines, the preparation of pigments and brushes, how to picturise the frontal and dorsal stances of figures and so on.
The Silparatnas injunction that a picture should be painted in appropriate colors along with proper forms and sentiments, or rasas and moods, or bhavas and actions seems to have been the working guidelines for Kerala murals.
White, yellow, red, black, and terreverte or Syama are mentioned in the Silparatna as pure colors. Besides, the different shades of these colors were also used. Ochre-red, ochre-yellow, white, bluish-green and pure green are the most common colors found in Kerala murals. We also come across golden-yellow, brown, yellowish-green, greenish-blue and sky-blue.
Color dyes were prepared from vegetable and mineral pigments as well as crude chemicals. These were extracted using simple methods. White was extracted from lime, black was the deposit of carbon soot of lamps, red and yellow dyes were generally extracts from minerals, blue was obtained from plants like Indigo Ferra, locally known as neel-amari, and green was prepared from a mineral known as eravikkara. Some ancient palm leaf manuscripts on painting mentions the use of chemicals like arsenic (Realgar) and vermillion (Red Lead) in the preparation of yellow and red dyes. The juice of lac was also used for making a deep red color. They also mention the application of lemon juice or copper sulphate solution over the ground for softening the alkali of like, before the application of colors. The colors were mixed in wooden utensils. The water of tender coconuts and gum-exudates were used as binding media. After the paintings were done, they were brushed over with a mixture of pine-resin and oil, which imparted sheen and strength to the pictures. Brushes made of feathers, or the fine roots of the Pandanus were used to apply this resin-oil mixture.
The Silparatna also describes the different types of brushes to be used. Mainly three types, like flat, medium, and fine, made from animal hair and grass fibres were used. Flat and medium brushes were made from the hair from the ears of calves, and the underside of the bellies of goats respectively. Fine tipped brushes were made either from the thin hair of the tails of muskrats, or grass tips.
The Silparatna advises the use of nine brushes, including three of each type, for applying the different shades of one color. Outlines were sketched not with brushes, but with dung crayons. The crayon outlines were run over on the outside, first with ochre-yellow and then with ochre-red.
The text also instructs the artists in the drawing of human figures. It describes the five main stances to be adopted in drawing figures, viz. frontal, half-frontal, askance, one and a quarter eyed, and profile, in great detail, which must have been extremely useful to artists. Dr Paramasivan, a famous archaeological chemist of India, has done valuable research in the techniques of Indian murals. It is he who classified the murals of Kerala in the Fresco-Secco category.
[From the publication Murals Of Kerala by M G Shashibhooshan, Dept. Of Public Relations, Kerala State. Reproduced here without permission, please advice if this information may not be carried here.]