The art of Fresco.
As an extension of the classroom and to fully understand the work of the artists being studied, the art history class spent a day participating in a fresco workshop. Fresco and mosaic artist Peter Boardman came to The Winsor School to teach the class to create frescoes of their own.
THE BUON FRESCO TECHNIQUE Fresco means "fresh" in Italian. It is an ancient technique of painting on a fresh wet plaster surface (called "intonaco"), usually on a wall. The paint penetrates the intonaco and the powdered pigments become part of the wall as it dries. This is a durable method of painting that binds the colors to the plaster.
Since Ancient Egypt, artists have been painting frescoes, many of which have survived. Fresco is different from other painting techniques, in that as soon as the wall gets coated with the intonaco, it starts to dry, giving the artist an eight-to-10-hour window of time to work. Thus, frescoes require painters to work quickly, pouring out their ideas with immediacy, vivacity and intensity.
In the 14th or 15th century, a fresco artist would sketch rough drawings directly on the wall to determine the sectioning of the fresh plaster. The joints would be visible and the artist would work from the top down so as not to drip on finished parts.
Because the intonaco must be painted while it is wet, the wall is coated with just the amount of fresh intonaco that an artist is able to paint in one day; thus, the art of fresco is necessarily piecemeal. This was a real drawback in the 15th century, when visual unity, light and atmosphere were considered essential to painting. A second type of fresco was developed in which the pigment is applied to the dry wall with a binder like egg; this method is less permanent, however, and flakes off.
THE MATERIALS Intonaco is the basic material for fresco. This Italian word, meaning "touch," describes the surface of the wall when the cement is applied to it. Intonaco is made from slaked lime, a lime powder to which water has been added. When water is added to the lime, it generates a huge heat reaction immediately. This procedure should not be done without proper equipment. The slaked lime must sit for at least three months before using, but it can be bought pre-aged.
Slaked lime slows down the drying time, and plasterers today still use it for that purpose. Mason and quartz silicate sand are added to the slaked lime and mixed with a trowel until the intonaco is the consistency of putty. Together, in a formula of one part lime and two parts sand, the slaked lime and the sand form calcium carbonate. Sealed airtight in plastic, the intonaco will keep for months.
The Renaissance palette was a limited one. Fourteenth- and 15th-century artists used about nine colors, most of them earth tones. They were created from small portions of powdered pigments mixed with water. Blue pigment is made from lapis lazuli, a semiprecious gem used since prehistoric times and comparable to gold in value.
Lapis blue pigment starts out as a large chunk of gemstone which is cracked into smaller pieces and ground in an electric stone grinder. It is then purified in a centuries-old procedure by mixing the powder into a paste with turpentine resin, beeswax and turpentine.
After drying overnight, the paste is put in a linen bag and immersed in a bucket of warm water. The water turns blue and, eventually, the blue pigment forms sediment at the bottom of the bucket. The water is poured off and the sediment is dried in the sun and filtered through a very fine sieve. A kilo of raw material yields about 20 grams of pigment.
As one might imagine, the history of pigments is connected to the development of the sciences. Most colors consist of metal compounds. Many, like lapis lazuli, were mined from the earth and are still mined from the original deposit. Others are manufactured according to historical recipes. Today, these pigments are commercially available.
THE PROCESS In an effort to simplify, all my students worked with a photocopied image of a detail from Masaccio's Tribute Money. At the beginning of the workshop each student prepared a cartoon (a preliminary drawing of what is going to be painted). This process consisted of pouncing, or perforating the cartoon's lines with a stylus or another sharp, pointed tool. Needle tools for ceramics work well.
In the workshops of the Renaissance, apprentices would have mixed the intonaco and applied it to the wall. Traditionally, fresco is done on walls, which are saturated with water until they cannot accept any more, then coated with the intonaco. The artist has a 12-hour timeframe in which to paint before the intonaco dries.
Instead of using coated walls, the class worked on thin pieces of cement board (called "wonderboard") coated with intonaco. Wonderboard affords four to five hours of painting before it becomes too dry to absorb any more paint.
In preparation for the fresco process, the wonderboard should be moistened under running water and allowed to sit, rough side up, in the sink. Using a trowel and a lot of pressure, the intonaco is applied to the dampened panel in a very thin, smooth coat. Then, the intonaco-coated panel must sit for about 30 minutes prior to transferring the image.
Our cartoons were transferred to the intonaco-coated panel by rubbing a pounce bag (small cloth bag filled with powdered charcoal) over the perforated drawing. The charcoal powder passed through the holes, leaving a dotted line of the image on the fresh plaster.
Finally, it was time to paint. An entire day was spent perfecting their paintings, and the students' efforts resulted in a class full of beautiful fresco images. By the following day, the paint was completely absorbed in the cement where it will be preserved for many years, just like the work of the artists that we had studied. This hands-on component of what is primarily an academic class gave one senior "a greater appreciation of what the artists we have studied actually went through."
To run a fresco workshop with students, the following materials are needed:
* Wonderboard (cut down to the size of the image, such as 8" x 10")
* Mason sand
* Quartz silicate sand
* Trowels or sturdy palette knives
* Powdered pigments (mixed with a small amount of water in jars)
* Brushes in a variety of sizes
* Needle tools or styluses
* Styrofoam blocks (to put under the cartoon while perforating)
* Pounce bag (small piece of muslin filled with powdered charcoal, tied with rubber band).
[Author's source for slaked lime (available as "pit lime") and pigments: Kremer Pigments, Inc., 228 Elizabeth St., New York, NY 10012.]
Note: Peter Boardman trained at the Museum of Fine Arts School and then taught in its Technical Painting Department. He runs fresco and mosaic workshops in the greater Boston area. He can be reached at P.O. Box 428, Harwich, MA 02645.--S.G.M.
Sara Grove Macaulay teaches studio art and art history at The Winsor School in Boston, Mass. Photos by Gus Freedman.
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|Author:||Macaulay, Sara Grove|
|Publication:||Arts & Activities|
|Date:||Apr 1, 2001|
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