Fresco technique

How did medieval painters paint cathedrals?

Fresco is a labour-intensive technique that requires high creative exertion, skill, speed and precision of work. The most suitable season for fresco painting is a warm summer period from May to September.

The wall painting started from the top of a cathedral and altars. Priming wet plaster was applied by masters daily to a section which corresponded to the outline of a figure or a scene so that the joining of two adjacent sections was not seen. Usually, the area of one daily section was 6 to 9 square metres.

When the plaster was laid, the surface was smoothed and vertical and horizontal lines were marked up on the wall. Then an underdrawing of the whole composition was sketched with yellow, red, brown or black pigments mixed with water and the main lines of the sketch were grooved with a sharp instrument.

Afterwards, masters covered a hallo and head of a saint with ochre and grayish green on top. Light salient parts were painted with light yellow and then limed with white in two movements. Faces (contours of eyes, nose and eyebrows) were drawn first in red-brown, then dark-green, almost black. Clothes were painted in a similar way: on the primary tone (green, pink, blue) wide stripes of washouts were laid. Shading was done in red. If there was a need, details and final touches were added on the dry plaster.

Paint was laid on wet plaster during a short period: while the mortar was drying, it absorbed the pigments. Such mortar was called ‘mature’. One could easily and freely paint on it until the movement of a brush stalled and the paint was not absorbed any more.

When the plaster dried, the crystals of the pigments permeated through the plaster layer and thus bonded to the wall. Some pigments such as red ochre, schungite, haematite do not change their colour at all, while others like ochre, lapis lazuli and glauconite get much lighter. Hence the master had to take into account the characteristic of each pigment and foresee the final result.

The specific character of medieval painting lies in a variety of individual methods and tricks within one and the same technique. It was described by Y. Dmitriev, a researcher of Old Russian wall painting as follows: “The brushwork process can be likened to superimposing several colour planes.”

These technological specifications affected not only the method (layering procedure) and the manner (layer application technique) but also the preparatory work, notably choice of pigments, colour compounding and surface preparation. When combining colours it was a special skill to balance a fineness of ground paste with large particles of pigment. When applying the paint it was important to preserve both the thinness of layers and its chromaticity. The process had to be divided into several stages: almost transparent layers were laid on more saturated ones. Surely, a great deal depended on individual craftsmanship, but equally essential was the skill to compound paint mixtures as well as the alternate layering method when different layers showed through.

Painting a cathedral, medieval painters achieved an amazing artistic expressiveness, harmony of painting and architecture which is manifested in the frescoes of the St. Ferapont Belozero Monastery.

Meaning of some terms:

1. Fresco (from Italian word “fresco” which means fresh) is a major technique of wall painting with pigments mixed with water on fresh wet plaster that form, when set, a thin transparent film that binds colours and makes the fresco durable.
2. Fresco primer as a rule consists of slack lime and mineral stuff: silica sand, powdered lime-stone, crushed brick and ceramics. Occasionally, organic additives (straw, hemp, flax etc.) are used to prevent the plaster from bursting.
3. Groove is an underdrawn sketch, marking up contours with a sharp instrument. It is made on plaster before fresco painting, otherwise the contours are not seen.
4. Pigments are colour substances or a colour powder that are part of any type of paint and determine its colour.

Colour pigments of Old Russian wall painting

«The micro-chemical analysis of the colour layer of wall painting determined that the palette of Old Russian frescoes was limited and numbered only 27 primary pigments, 16 of which were of earthen origin and 10 natural minerals. On some occasions artificial pigments were used (white lead, red lead, yellow, verdigris, azure, blue, black, smalt). Despite the limited number of primary pigments Old Russian painters created an extraordinarily rich colour palette by means of skillful mixing and laying one colour over another one. Undoubtedly, most of colour pigments used by Old Russian painters in frescoes are durable, exposure-resistant and can be applied in modern wall-painting” (A. Viner Paints Used by Russian Painters in the 11th-17th Centuries in the Wall-painting).