Fundamentals of Fresco Painting

A difficult technique with unique artistic results

When Michelangelo painted the ceiling of the Sistine Chapel, he not only had to stand with his head craned backwards and his arm raised for hours at a time, but he also had to work in the technically challenging medium of fresco.

Fresco painting has two supreme qualities: the first is that it involves applying paint onto freshly laid plaster, meaning it is apt for large murals that cover entire walls — or in the case of the Sistine Chapel, an entire ceiling too.

The second quality of fresco is that it must be made with confidence and speed, since there is little room for error and incomplete sections usually have to be re-plastered and painted again. This aspect means that fresco paintings often have a vivid and monumental feel, where finer details must be simplified in favour of prominent and clear-sighted designs.

One of my personal favourite series of fresco paintings is at the monastery of San Marco in Florence, where the artist Fra Angelico decorated the monk’s living quarters with scenes from the life of the Virgin Mary and Christ. These paintings are fine examples of the power of fresco: uncluttered, compelling and immediate.

The reason for speed is because with fresco painting the pigment is applied to fresh plaster whilst it is still damp. The word fresco is Italian for “fresh”. The artist must therefore work quickly to complete the apportioned section of plaster before it dries. The pigments, which are made by grinding dry-powder colour in pure water, are painted whilst the plaster dries to become a permanent part of the wall.

In order to achieve this, the artist must plan out the stages of the painting carefully, dividing the image into appropriate sections.

If you look at the image shown here, of The Expulsion from the Garden of Eden by Masaccio, you can see how the wider work would have been split into days.

With each day, a thin layer of wet plaster called the intonaco (Italian for “plaster”) is applied to the area to be painted. The artist must work within the plaster’s curing time — a day’s work, or a giornata in Italian.

If you look closely, you can see the dividing lines between each section of giornata. A correctly prepared intonaco will hold its moisture for many hours, perhaps as much as nine or ten, giving the artist time to complete a single section in a day.

The fresco mural technique has its origins in antiquity, going back at least as far as the Minoan civilization, as seen at Knossos on Crete. It was also widely used by the ancient Romans as decoration for important rooms.

Over time, two alternative fresco techniques emerged. Up until the age of the Renaissance, the secco method tended to be more prominent. In this method, the paint is applied onto plaster that is already dry. Essentially, this is painting directly onto wall. Usually the pigment is mixed with a binding medium — either egg white or lime —to act as the glue. It is an easier method but has the drawback that the pigments are not completely absorbed by the plaster and may flake in time.

The second method is known in Italian as buon fresco or “true fresco” and results in a more durable finish. Many of the outstanding fresco works of the Renaissance were made using this technique.

In this method, a coat of rough plaster (arriccio) is applied to a stone or brick wall. Once dried, the artist makes a preliminary drawing onto the wall. This initial drawing is reinforced with red paint (sinopia) to give a more finished quality to the sketch.

The purpose of the sinopia underpainting is to flesh out the planned image before the final coat of plaster is applied. It makes it easier to plan for the various days to come, and also allows the commissioning patron a chance to see the work and give their approval.

Finally, a smooth coat (intonaco) of plaster is applied to as much of the wall as will be painted in that session — at which point the artist gets to work.

Since the wetness of the plaster naturally changes over the course of the day, the artist must dilute their paint with water to keep the same tone across the giornata. Once dried, no more buon fresco can be painted on that area. If mistakes have been made, it is not unusual for the whole section of plaster to be removed and then repainted the following day. The alternative is to add finer details using the seccomethod.

Fresco paintings have a particular look and feel. As the wall dries and sets, the pigment particles become bound or cemented with the plaster. The surface texture is dry and opaque, giving rise to an appealing chalky feel, since the paint is an integral part of the wall surface.

When put to best use, the fresco effect can be lively and expressive, with bold designs and well-defined figures. When a fresco occupies an entire wall space or sometimes the whole interior of a building — as in the decorations for the Scrovegni Chapel in Padua by Giotto — then the results can be spectacular.