Fresco Painting (Ital. fresco, fresh), a method of ornamenting the walls and ceilings of buildings by painting designs in colors ground in water and mixed with lime upon the freshly laid plaster. It was much practised by Italian masters during the three or four centuries immediately succeeding the revival of painting in modern times, and the walls of many Italian palaces, churches, and convents are still adorned with works executed by their hands. The outlines of the designs are first drawn upon thick paper attached to cloth, which is stretched upon a frame. These are called cartoons, from the Italian cartone, pasteboard. An additional colored cartoon is also prepared to serve as a study of color, and a guide during the execution of the fresco. The famous cartoons of Raphael, now deposited in the South Kensington museum, London, are of this character, although made to be copied in tapestry. The cartoons serve to give copies upon tracing paper, and these being attached to the wall in portions of convenient size, the outline is transferred to the wet plaster by going over the lines with a sharp point.

Another method is to prick the figures through the cartoon, or upon a separate sheet laid behind it, and then, placing either the cartoon itself or the duplicate sheet upon the plaster, to dust through the holes a black coloring matter, which attaches itself in the lines of the figures to the walls. Several great painters have worked immediately on the plaster, without the intervention of any guide whatever. The preparation of the walls is an object of especial care. All the mortar should be fresh work, and of clean sand and good lime. When the rough coat is perfectly dry and hard, the smoother layers are added of the most carefully prepared mortar. In Munich, where fresco painting has been revived with some success during the present century, the lime is sometimes slaked several years before it is used, and is kept, after thorough stirring and reduction to an impalpable consistency, in a pit covered with clean sand a foot or more in thickness, over which earth is laid. Pure rain or distilled water should be used in mixing it, and also perfectly clean sand. The rough coat being dampened till it will absorb no more water, the finer plaster is laid on, and when this begins to set a still finer coat, called by the Italians the intonaco, and containing a smaller proportion of sand, is applied.

Before this dries, the design must be transferred to it and the painting completed; consequently only small portions of a fresco can be executed at one time. The drying may be checked by occasional sprinkling with water, or by keeping wet sheets pressed to the design, as it is attached to the wall. The joinings or lines between the work of one day and that of the next are made to coincide with lines in the composition, or take place in shadows. As any retouching is impracticable, the painter must work rapidly before the ground becomes too dry to take the colors. If others are afterward applied mixed with size, white of egg, or gum, which is in effect only tempera painting, they do not long continue to harmonize with the rest of the work. The colors must be of substances not liable to be affected by contact with the lime, and those of a mineral nature are almost exclusively used. Lime, or the dust of white marble, makes a good white. Chrome, the ochres, verditer, lapis lazuli, etc, furnish many of the colors.

The brushes must be so soft as not to roughen the plaster surface.-In addition to the process above described, which was called by the Italians buon fresco, or the true fresco, the early masters had other methods of painting on lime or plaster, to which the general name of fresco is usually applied. The most important of these was that known as fresco secco, or dry fresco, so called because the plastering, having been allowed to dry thoroughly, was remoistened before the color was applied, whereby the artist was enabled to quit or resume his work at pleasure, and to avoid the joinings observable in the true fresco painting. This process was universal in Italy until the close of the 14th century, when buon fresco in a measure took its place. In this manner were probably executed the paintings in Pompeii and Herculaneum, and, indeed, all the so-called ancient frescoes. Work done in this way will bear to be washed as well as real fresco, and is as durable; but it is considered, in every important respect, an inferior art.-A new method of preparing the wall and painting in fresco has been introduced in Germany by Prof. Von Fuchs, called the stereochrome.

The wall is coated with a preparation of clean quartz sand mixed with the least possible quantity of lime; and after the application of this the surface is scraped to remove the outer coating in contact with the atmosphere. It is then washed with a solution of silica, prepared with silica 23.21 parts in 100, soda 8.90, potash 2.52, water 65.37. The wall is thus said to be fixed; and if too strongly fixed, it must be rubbed with pumice. As the painter applies his colors he moistens the work by squirting distilled water upon it. When finished it is washed over with the silica solution. The picture also, as it is in progress, is washed with the same solution, and the colors thus becoming incorporated in the flinty coating, the picture is rendered hard and durable as stone itself. In this process the artist may leave the work and return to it at any time, and he is also able to retouch and alter any portion of it. The new museum at Berlin has been adorned by this process by Kaulbach. The decorations are historical pictures, 21 ft. in height by 24 3/4 in width, and single colossal figures, friezes, arabesques, etc.

They have the brilliancy and vigor of oil paintings, with no dazzling effect of light from whatever direction they may be viewed.-Old paintings in fresco have been transferred to canvas from walls crumbling by decay, and thus preserved. A linen cloth is applied to the face of the painting, covered with a kind of glue. The intonaco, or last coat of plaster, is then carefully detached from the wall with a knife. The rough surface at the back having been rubbed down with pumice stone, until the plaster is reduced to the thinnest state consistent with the preservation of the painting, canvas is fastened upon the back, and the cloth in front moistened and removed. The detached fresco may then almost be treated like a common oil picture. It is quite common in Italy to remove by this method fres-coes of value, for sale, or for preservation in public museums. Such was the process successfully employed in removing and preserving the paintings on the old walls of the convent of Sta. Eufemia at Brescia in 1829.-The history of fresco painting during the first two centuries after the revival of art is a history of painting, as nearly every considerable work was executed by that process.