In different fields, certain workers do find it desirable to-day to combine dry colours with a tempera medium. For example, commercial illustrators have discovered that it is possible, by the admixture of dry pigment with a gum arabic-glycerine compound, to obtain colour of much stronger intensity—saturation—than can be had in commercial water-colour. This method of working has the advantage that the strength of the prepared colour is within the artist's control. It is also claimed that it is possible to obtain a very even and flat tone and one that, because of the absence of reflections, is particularly adapted to photographic reproduction.
Doubtless there are many other forms of artistic endeavour in which use is made of tempera mediums with dry colour, as in some forms of modern fresco, for example, but tempera, in its modern application is, like oil painting, almost entirely a matter of the use of prepared colours. These are ground by the manu facturers in various colloidal, gelatinous or albuminous vehicles and sold put up in tubes, pans or pots, but, unlike oil, the products of different manufacturers differ so greatly in character as to necessitate completely different techniques. The product of some colourmen is to be used with the addition only of water, while in other varieties the use of prepared "tempera mediums" is necessary. These are, naturally, compounds similar to the vehicles in which the particular colours are ground. It may be noted that ordinary water-colour, show-card colour and the like, are of course, strictly tempera, being ground in gum arabic and glycerine, although water-colour is only characteristic of the tempera medium when used as gouache or body colour.
As noted above, the products of different colourmen vary so radically that it is difficult to give any idea of present day tempera technique. In common they all present the quality of opacity; they may be used upon a great variety of surfaces and, in most cases, the permanency of the results depends only upon that of the ground. Due to their opacity, they may be used to very great advantage on dark grounds—a method of painting which has much to commend it. Most of the temperas in the market, however, are subject to the rather serious objection that the colours become lighter in drying.
Except as used for under-painting, tempera painting of to-day is a direct process. Unlike oil the colour usually dries very quickly upon the ground and any alteration of a tone by "painting into" it is difficult to achieve successfully. This directness, this premier coup quality, is one of the charms of the medium and also makes it desirable for quick sketching.
Most users of tempera to-day are in the habit of employing it very flatly, frequently in the form of spots or "lozenges," so to speak, of clean colour applied to grounds which vary from grey or brown to black. This technique is highly characteristic of tempera painting as it is found in the water-colour shows of the United States. But some forms of commercial tempera may be used in a manner which approaches oil in appearance and in which the broken quality of a partially mixed tone may be pre served. For this type of painting very little or no medium is
used; heavy water-colour paper is employed as a ground and this may be obtained in a variety of tints from white to black.
A number of prominent artists still use tempera as the medium with which to commence paintings which are completed in oil.
Emil Carlsen, one of the most noted of those who employed this technique, used an absorbent canvas, certain commercial colours and a commercial egg medium. For the first painting he recommended the using of the colour thinly, with water as a medium. This completed, the canvas is allowed to dry for a day or two, is then given one or two coats of tempera varnish A, and again let dry for a few hours. The picture is now given a light wash of the egg tempera medium and the painting is continued, using egg tempera as the medium instead of water. The colours can now be used solidly but it is necessary to lay layer over layer and let them dry between times or the colour will crack. "The result," said Mr. Carlsen, "is an extremely hard and light underpainting, that, if varnished with a good coat of tempera varnish, well dried, will hold up a piece of painting wonderfully and give it more luminosity in the picture's future than any other process." It will be evident that the art of tempera painting is even more difficult to limit and define than is painting in oil. It is an art the technique of which varied greatly, as did the vehicles em ployed, even in its classic period, and this is equally true as to the more or less sporadic revivals of the old processes which are employed to-day, while, as to the commercial tempera of the shops, the colours supplied by one manufacturer may possess radically different qualities and call for a totally different tech nique from those of another manufacturer, and still be equally desirable. But in this very lack of uniformity is an incen tive to the artist who is seeking for an individual, a personal tech, nique. Whether he seeks for this in the use of prepared products or in the study and application of the ancient methods he will find in tempera a number of subtle and illusive charms which will well repay him for the search. (See also PAINTING; OIL PAINT ING TECHNIQUE; PAINTS, CHEMISTRY OF.) BIBLIOGRAPHY.-Cennino Cennini, Il Librd dell' Arte (c. 1432), trans. by C. J. Herringham with "Notes on Mediaeval Art Matters" (London, 1899) ; Vasari on Technique, trans. by Louisa S. Maclehose (New York and London, 1907) ; M. Toch, Materials for Permanent Painting (London, 1911) ; A. P. Laurie, The Pigments and Mediums of the Old Masters (London, 1914), The Painter's Methods and Mt! terials (Philadelphia, 1926) ; M. Armfield, "Tempera," Int. Studio (Dec. 1916) ; Roger E. Fry, "Terripera Painting," Burlington vol. vii., p. 175 (1895) ; Sir Arthur H. Church, Chemistry of Paints and Painting; Theophilus, Schedula diversarum artium (Vienna, 1874), Papers of the Society of Painters in Tempera (London, 1891-1907), and Papers of the Society of Mural Decorators and Painters in Tern pera (Brighton, 1907-24). (Y. A.)