What is a Fresco?

   Fresco is a type of painting done on fresh plaster. The pigment is ground in water and applied to wet lime plaster, which on drying incorporates the pig­ment in a film of crystalline carbonate of lime. The white lime is customarily used as the white pigment. Only limeproof pigments may be used, but these are exceptionally permanent. Indoor frescoes are among the best preserved of mural paintings, and in certain climates outdoor frescoes have been known to with-stand exposure remarkably well. True fresco is water­proof.
   The fresco painter, in order to visualize his work, often transfers his drawing to the wall before the application of the final coat of thin plaster (the intonoco). Only as much of the final coat of thin plaster is applied as the artist expects to cover in one day, and any unpainted portion is removed at the end of the day's work. A large fresco thus consists of a great number of small sections, often planned to co­incide with the contours of the objects represented in order to make the joinings less conspicuous.
   The art of true fresco, or buon fresco, reached a high development in the Italian Renaissance and has seen a remarkable revival in the 20th century. Fresco secco, or painting on dry plaster with color ground in a glue medium, simulates true fresco but lacks some of its fine qualities. It has been used to retouch fresco, which otherwise does not permit of any changes when dry.
   Because of its permanence, clarity, and fine surface which does not vary or reflect light unevenly, fresco is an ideal medium for mural pairting. It is an exacting medium and demands expert craftsmanship.