Fresco

From Principles of Applied Arts

In buon fresco, true fresco, dissolved pigment is applied to wet lime plaster. As the lime carbonates and moisture evaporates, the pigment layer is locked into the fine chrystalline layer that forms on the surface of the plaster. This system is literally reverting back to stone with those colors attached to it. The absence of any modifying medium keeps the clarity of color that we still see in so many centuries old frescoes. Some of the drawbacks to using buon fresco are: The color varies incredibly from wet to dry and it could take years for an artist to develop his eye for colors properly. The paints in a fresco take weeks to dry. The painter also brings water out of the base coat which, while giving fluidity to his strokes, alters the chemical reaction that gives strength to his lime surface. In effect, he weakens his own work. Early Roman fresco was recommended at 6 coats of progressively fine textured lime plaster. Plaster made of slaked lime and marble dust was best. A cartoon rendering of the mural was then pounced onto the surface with a wet brush. The next step was measured according to one days work. Only the space that could be completed in one day was painted, with the edges beveled off the allow joining the next day. These joins would then be invisible to the untrained eye

Fresco by Dionisius representing Saint Nicholas. In painting, the term fresco (pl. frescoes) comes from the Italian phrase 'buon fresco,' (really fresh) a technical term in opposition to 'in secco' (on dry surface). True, or 'buon fresco' technique consists of painting in pigment in a water medium on wet or fresh lime mortar or plaster. 'In secco' painting is done on dry plaster and with the pigments in a binding medium, like egg. The difference between the two techniques is that as it dries the wet plaster absorbs the pigment and the painting becomes part of the wall surface rather than resting on top of it. This makes a durable work of art; if the wall is destroyed the painting can often be reassembled because of the size of the plaster parts. Because of the need to work on freshly laid plaster, careful study of the wall surface can reveal the area worked on in one day. In Renaissance Italy this was commonly called a 'giornata' or a 'daily amount.' These divisions are perceptible with mild magnification and even the naked eye if the plastering technique was not good. Painters in fresco often add details later 'in secco.' These details are not part of the wall and so they are much less durable. Egyptian wall paintings in tombs are usually 'in secco,' while the Roman wall paintings at Pompeii and Herculaneum are in fresco. Andrea Palladio, the famous Italian architect of the 16th century, built many mansions with plain exteriors and stunning interiors filled with frescoes.