-by Gautam Shah
Fresco (Italian =fresh), is a method of loading colours on a wet or green plaster. The term is mainly applied to art of creating paintings, but may include craft of painting the architectural entities like walls and ceilings. It was a slow and labourious process, but for many centuries, it was the only viable process for rendering a painting on a masonry surface and for applying architectural colour.
Fresco technique of coating was not suitable for wood, or other soft surfaces. Metals and alloys were new materials at that time, and being mostly non ferrous did not require any additional finish.
In true or real fresco, the colourants pigments are applied to the top layer of a multi layered plaster system. First or more layers of plaster were applied for structural and levelling purposes. The final and thinner was scratched to imprint the outline or sketch of the scheme. The sketch was drawn directly or imprinted by using a full size replica drawn on cloth (and later paper), called a cartoon. The cartoons were often reused in different works of art. The outlines of the various figures and forms were than filled-in with indicative dark water colours. A topping or finishing plaster was laid over the drawing in small sections, and each section of wet plaster was loaded with colour. As the plaster dried, the lime in the plaster, on absorption of carbon dioxide from the air, formed a calcium carbonate. This formed a film over the colours, to bind them to the plaster mass.
The colours of a fresco are usually thin, translucent, and light, often with a chalky or pastel look. It was not possible to achieve saturated hues due to dominant presence of white of Lime. It was very necessary that before the plaster set, to quickly finish the section of the painting. So most paintings lacked finer detailing and perforce consisted of bare essentials. As the work was carried out segment by segment, it reflected in the style of painting. In early works of Fresco painting such compartmentalization is very apparent. In later art works paintings were overdrawn to create graduated or tonal variations. Wherever defective portions were removed by scratching the plaster, and redone patchy effects were inevitable.
The artist had to be well aware as to amount of colour the plaster will hold or absorb. Too much pigment caused the surface to become chalky or powdery.
In Fresco the fixing of colour was not controlled. It gave a patchy colour effect with differing fixation. As a result, variety of fixers were devised out of size, starch, gums, and plant excreted resins. These fixers were mostly hygroscopic, so used to run in wet weather or developed fungus. Plant resins had a few problems that such fixers on drying provided comparatively a flat or dull-matt finish. Plant resins were acidic in nature and not always suitable for alkaline masonry surfaces.
Fresco painting was known to the ancient Egyptians, Cretans, and Greeks. The Romans also practised fresco painting, examples are found in Herculaneum and Pompeii. In early Christian times (2nd C AD) Frescos were used to decorate the walls of catacombs, or underground burial chambers.