The Art of Fresco Painting

Recently, I went on a week-long trip to Italy, the birth of the Renaissance, and the birthplace of one of my favorite artists, Michaelangelo. Even though the trip didn’t include many museums, I managed to visit a few in my free time, including the Sistine Chapel, where some of the most famous artists, including Michaelangelo, were represented. I found that a lot of Italian art were in the form of frescos, many of which are still visible after hundreds of years of pollution and water damage. I realized that I didn’t know how these paintings were made, so I did some research.

The word fresco is derived from the Italian word for "fresh." Fresco or Buon fresco is a technique of mural painting applied to freshly laid lime plaster made of pozzolana (volcanic material, predominantly composed of fine volcanic glass), water and lime. The artist would combine dry-powder pigment with water and apply it to the plaster. The colors had a translucent quality at first. As the pigment was absorbed into the plaster, a process called carbonization occurs. Carbon dioxide in the air combined with the lime in the plaster formed a rock-hard surface of calcium carbonate, cementing the pigment into the wall surface.

The under layer, called arriccio, is laid slightly coarsely and is left to dry, usually for some several days. Using a full-scale drawing, the artists transferred the outlines of the design onto the wall from a tracing made of the drawing. On the dried arriccio, in early frescos, the artist sketched the sinopia, using a dark reddish-brown natural earth pigment. Once dry, the wet layer, the intonaco, is applied. Intonaco is an Italian term for the final, very thin layer of plaster. The intonaco is painted while still wet, in order to allow the pigment to penetrate. This layer was only the size of the surface that was expected to be completed that day, the giornata (Italian for “day”), sometimes matching the contours of the figures or the landscape, but more often just starting from the top of the composition. A layer of plaster will take seven to eight hours to dry. The artist would start to paint one hour after the application and continue until two hours before the drying time—giving about five- or six-hours’ working time. Once a giornata is dried, any unpainted intonaco must be removed with a tool before starting again the next day.

Some pigments did not work well applied on intonaco because of alkalinity of the plaster. Blue was a particular problem, and skies and blue robes were often added a secco (“dry”), because neither azurite blue nor lapis lazuli, the only two blue pigments then available, would work with wet plaster. Colors applied to dry plaster required a binding medium, such as egg tempura, glue or oil to firmly attach the pigment to the wall. Over time, Buon fresco paintings lasted longer than a secco, since it bound well with the plaster.

Artists transferred their paper drawings to the wall by tracing along the larger areas of the drawing with a thin piece of wood that pierced the paper and left a light indentation on the surface. Another technique called pouncing involved pricking the paper along the lines of the drawing with a pointed instrument leaving small dots. The artist would hold the drawing on the plaster surface and, with a bag of soot, rap the surface of the paper over the dotted area, leaving a line of black dots on the plaster surface.

A technique used in the popular frescoes of Michelangelo and Raphael was to scrape indentations into certain areas of the plaster while still wet to increase the illusion of depth and to accent certain areas over others. Michelangelo used this technique as part of his trademark “outlining” of his central figures within his frescoes.

The fresco painting technique has been employed for thousands of years, but is most commonly seen in early Renaissance art. During the sixteenth century in Italy, wall painting began to include oil painting on canvas as the need for portability and the support from wealthy merchants competed with church patrons.