Regarding technical modes or processes of painting, reference is made to the separate notices under FRESCO, ENCAUSTIC, MINIATURE.PAINTING, The period when the method of mixing up colors with oil was introduced, and the artists to whom the invention is attributed, have been already alluded to. It is necessary, however, to enter on some details touching the mechanical processes in oil-painting, the branch of the art that occupies the most prominent position; and the practice of cleaning and restoring pictu res.
The implements used by a painter in oil are charcoal, chalk, or lead pencils, for drawing the outline; hair-pencils or brushes of Various sizes, made of hog's bristles or finer hair, such as sable; a knife or spatula to mix the colors, and a palette or small table of thin wood, to be held in the left band, on which the colors and tints are placed and mixed; an easel or stand for supporting the picture is also required, and a light rod for steadying or resting the hand on. Large pictures are always executed on canvas, stretched tightly on a frame, and printed or coated with paint. Small pictures are often painted on boards or panels, generally of hardwood, such as oak or mahogony, and similarly primed or prepared; but canvas, even for small works, scents at present to be generally preferred. Panels are apt to twist, or warp, or split, and in the event of the surface of a picture chipping or breaking off from the ground, the damage can be more easily remedied, and its progress stopped, when the picture is on canvas, by re-lining:. The color the ground of the canvas or panel has been the subject of much diversity of opinion among artists in different countries and at various periods; and it is certainly a matter of great importance, as it affects the general color of the work, or makes it necessary for the artist to adopt a peculiar style of working. The color of the ground used by the early masters was white, or nearly purely white. This arose from tempera or size being the medium first used in painting, and a pure white ground prepared with size was neces sary for that kind of work. This practice, except as regards the Venetian school, con tinued till the decline of Italian art. Dull red was the universal color adopted in the eclectic, naturalistic, and late Italian schools, and this is one of the causes of the works of these schools being characterized by blackness and heaviness; at the same time, it is certain that red grounds were also used by many of the best Venetian painters, in whose works these defects are never found, probably from having used an impasto or body of color suffciently powerful to bear out on the ground. A dark ground affords a facility for working expeditiously, and that„ probably, was the principal cause for its being adopted. Tee Dutch and Flemish painters generally used light grounds; some of them light-brown, nearly the color of oak. Van Dyck occasionally used gray. and sometimes, when he painted in Italy, dull-red grounds. In the British school, light grounds are preferred. Some artists use smooth canvas, others prefer it rough, and avail themselves of the texture to increase the richness of the surface of their work. All these varieties in the materials are called for in consequence of the numerous styles or modes adopted by painters in oil colors. Every artist has his peculiar way of working, and in bringing out the color or effect, or special quality in his picture, by which the feeling or idea of the subject he conceives is expressed. No two artists—imitators and copiers are not
referred to—produce their tints by mixing colors in the same proportions, nor, indeed, by using the same colors; and it is difficult to lay down general rules for the ex.ention of works, seeing that depends very much on individual feeling and appreciation. The design or drawing is first outlined on the canvas, if it is light, with charcoal, or with white chalk when it is dark, and these lines are easily dusted off or rubbed out when corrections are made. It is then put in with black chalk or a lead pencil. Not many years ago it was the practice of painters, particularly landseape-painters—Nasmyth. for instance—to rub in the design with some brown color, such as a tint composed of burned sienna and black; but this practice is not much adopted now. Some artists make but a slight outline, and as it is called technically, rub—in the subject in a bold, rough manner, afterwards gradually finishing it up; others draw the design very care fully, and work the picture up in portions, finishing or nearly finishing one portion before commencing another. In arranging the colors, or as it is called, setting the palette, many artists use a great variety of colors, others produce rich tones with few colors; some mix up tints in various gradations, others place the colors on the palette, commencing at the outer edge with white, followed by yellows and burned sienna (a reddish brown), then reds, including lakes, such as pink, madder, next blue, and lastly black, and merely mix up the tint on the center of the palette with their brush, as they proceed. In laying the colors on the canvas, the painter with his brush mixes or dilutes them with what is called a vehicle or medium. Here, again, the practice of artists is very varied; and this is a matter of importance, as the tone and quality of the picture, as regards texture or surface and transparency, is much affected by the medium employed, and the manner of using it. The durability of the work also depends very much on the medium and the artist's management of it. A medium composed of mastic varnish and drying or boiled linseed oil, named magilp, is that most generally used. This mixture coagulates or forms a jelly, and has the advantage, when placed on the palette, of not running off it, or mixing with the colors when the palette is not held level. Some painters prefer using raw linseed oil mixed with a dryer, such as litharge, or drying oil mixed with turpentine, or copal varnish and turpentine, or copal varnish and oil, with mastic varnish added, to make it coagulate. Other ingredients are often mixed with the medium to give a thick consistentcy to the paint, such as fat or thickened nut oil, paste, etc.; and various preparations sold by artists' colormen are much used; for instance, Roberson's medium, and Siecatif de Harlem, a preparation imported from Paris. The mode of using the medium is of great consequence; some apply it very sparingly, others, particu larly those who prefer magilp, or a medium that coagulates, employ it lavishly. By the first method, firmness and decision of touch may be exhibited, by the latter, richness and brilliancy of tone; the excess tends to produce, in the one case, a hard and dry sur face, and the want of the protection that varnish mixed with the color gives against atmostheric action; the other induces a surface having a horny appearance, and a ten dency to darken, or crack, or open up.