FRESCO PAINTING. The word °fresco° is Italian and means fresh. The term °fresco painting° means, technically, painting on a freshly laid wet surface of plaster. The method is employed in the decoration of spaces on walls and ceilings. The pigments used are water colors. By extension the term has been used to include other systems of painting. on plaster and has, at last, become, to some extent, accepted in popular parlance as synonymous with mural decoration in general. Some of the most noted paintings of the early great masters are in this medium.
an absorbent surface is needed on which to lay the plaster background, in cases where the wall structure is of hard, impervious stone, it becomes necessary to add a lining of brick. Over this is spread a three quarter-inch layer of mortar consisting of lime (at least a year old), well-washed river sand and an admixture of ox-hair or other durable fibre. This coating is combed over coarsely to produce a roughened surface' and is left to dry thoroughly (preferably a year) before further manipulation. Next comes the second coating (termed the intonaco), on which the painting is done. The aim here is to get this last plaster as absolutely homogeneously mixed as pos sible, as any imperfections or irregularities in the density of the plaster will cause lack of uniformity in the coating pigments when ap plied and unequally absorbed. To this end the finest quicklime is slaked and strained through a close-meshed sieve, then even grained river sand is added till the mixture becomes, on cooling, a putty* or The next process is to saturate the brick sur face with water and then lay on the plaster (intonaco), starting from the top and covering only as much as will suffice for the day's color work, say five hours, by which time the plaster gets too dry to absorb sufficient pigment, so that it would be likely to scale off later. When too dry the unpainted plaster must be cut away and fresh applied. After the freshly-laid plaster has had about 10 minutes to set it is best coated with a tint that will, when dry, afford a deep vellum surface tone (raw sienna and white lime of cream consistency). Next, the area of the day's color work is traced di rectly from a cartoon containing the subject, or through a tracing paper copy, by a stylus (point), or by punctured indications of the outlines. The painting now proceeds according to the method and style desired by the artist — applying thin washes as in water color painting or in thick brushwork (impasto), or both in combination. The bolder and larger surface of the brush can be shaded with addi tional pigment; or shading is frequently done by Thatched" lines. The process involves bold ness and lightness of stroke as each application of color is permanent and allows no correc tions and any hard pressure disturbs and ruins the soft wet surface. The pigments are limited to: White: lime white; yellow: raw sienna and cadmium yellow; red: vermilion, light red, Indian red; blue: cobalt blue and genuine ultramarine; green: oxide of chromium and emerald oxide of chromium or cobalt green; orange: burnt sienna; brown: raw umber, burnt umber; black: ivory black. The strict
limitation of the permissible range of pigments is caused by the need of each being able to resist the caustic action of lime in the plaster. This restriction of the palette has caused other processes of painting on plaster to be practised (mentioned later) and, in order to distinguish this original method from others, it has been termed gfresco-buono° (good or true fresco). This fresco-buono, correctly carried out, is more permanent than any other painting proc ess, 'except the. silicious glaze decoration in ceramics. The chemical action creating this extraordinary durability is supposed to be caused by the formation of carbonates, and sometimes silicates, of lime on the surface of the plaster while drying; the eliminated car bonic acid of the kiln action being again ab sorbed from the air by the hydrate and produc ing, while drying, a hard skin which protects the surface against atmospheric action and becoming damp-proof. It is not, however, im pervious to the action of sulphuretted hydrogen thrown off by coal-gas. Other processes of painting on plaster have been invented to avoid the inconveniences of the wet or fresco method. One is the afresco-secco" or dry process. Among the old writers useccoo referred to dis temper (tempera) work, using pigments ground in a binding medium, as egg, glue, size, gum, on a dry wall space. But the term secco in recent years refers to any dry processes, such as the German ((stereochrome° or °water glass') process, or the later innovation known as the Keims process. Among other schemes for increasing the usable range of pigments is °spirit fresco" done by grinding the colors in wax, then thinning with spirits of turpentine or oil of spike. The so-called ''encaustic' fresco-painting is done by using wax as a medium and after its application it is heated and thereby becomes absorbed, to some extent, by the ground. The English "spirit* fresco, invented by Gambier Perry of Gloucester, was used in decorating Saint Andrew's Chapel in Gloucester Cathedral, etc., also was later em ployed by Lord Leighton on mural decorations in the Victoria and Albert Museum and other buildings. Time alone is the test as to their clar ability. As to the technique of the artist in the fresco medium, the fact that a fresco painting is a wall or ceiling decoration involves the consequence that the conceptions, in de sign and execution, shall be architectural. Quite distinct from oil color painting, with its mul tiplicity of tones and gradations unlimited, the fresco work has, correctly, to consist mainly of more or less flat background that conveys the idea of surface more than distance, while the subjects exist more in outline and perspec tive than in detail of merging light and shadow.