Fresco is a painting technique wherein the paint is applied to a plaster wall, or the “intonaco,” that is still wet, so the wall absorbs the color of the paint while drying. This method makes the painting permanently set on the wall, evidenced by a matte, less shiny finish, as opposed to applying paint to an already-dried wall. Paintings usually done this way are usually on a larger scale than the usual paintings, which is why spacious walls are preferred surfaces. Probably the most famous fresco paintings are those on the ceiling of the Vatican City’s Sistine Chapel, where the Renaissance man Michelangelo painted many of the Bible’s most prominent stories and characters.
The meaning of the word “fresco” in Italian is “fresh,” most likely in reference to the fresh and still-wet plaster wall as the canvas. Historically, frescoes can be dated as far back as 30,000 years ago, when frescoes were seen in some limestone caves in France and Spain, with paintings of animals such as horses, lions, bison, and even the extinct mammoth. The use of plaster made of limestone began in 1500 BC and became prevalent in the Mediterranean regions like in Egypt, Greece, and Morocco, where the frescoes have religious purposes, as many of them were seen in tombs and burial sites. Samples of plaster painting were also found in some Asian countries, such as in India and Turkey.
Aside from the fresh plaster wall, another important component of a fresco painting is the paint itself. Traditionally, the paint is made from naturally-derived ground pigments, which are then mixed with water. The paint is then applied to the wet plaster by a brush, and both components are dried at the same time. Usually, the painter, or the “frescoist,” draws the general outline of the painting with red chalk or the “sinopia.”
There are three general types of frescoes, depending on the freshness or wetness of the plaster surface. The first type is the “buon fresco,” literally translated as “true fresh,” because this type uses the wettest plaster for the surface. Mixed with water only, the pigment is applied on the wet plaster, which fully absorbs the paint while it dries. To ensure its wetness, the plaster is applied on the wall part by part, according to how much work the painter can finish in a session.
The second type is the “mezzo-fresco” or “middle fresh,” as the plaster is only slightly wet, but dry enough for fingerprints not to be formed. This method allows only a moderate absorption of the paint. The “a secco,” or the “dry” type of fresco painting, uses dry plaster for the canvas, and this requires another binding agent for the pigment other than water, such as an egg yolk, oil, or glue. This allows the paint to bond with the wall, but does not really allow penetration. Leonardo Da Vinci created his famous painting, “The Last Supper,” using the a secco method.