Egg tempera (Video)
Simone Martini – The technique
The paintings of the Thirteenth and Fourteenth Centuries show a significant continuity in the use of materials and techniques: the use of the wooden support, the
ground preparation with gypsum and glue, the egg tempera painting, the process of gilding, can be found over a long period of time, albeit with significant variations in relation to the production centers. The knowledge of the techniques used has recently been deepened thanks to scientific investigations, but the primary source remains, for this period, The Book of Art, written towards the end of the Fourteenth Century by Cennino Cennini, a painter heir to the Giotto tradition and, for what he describes in his treatise, definitely representative of the ways of proceeding of the Fourteenth Century painters. Following Cennini’s text, we can try to retrace some of the possible choices that a painter of the time would have made in creating a painting on a wooden panel, focusing, in particular, on the methods of transferring the drawing and on the gilding operations.
Cennini, without forgetting the slightest detail, teaches “the way of those who know the art”: from the choice of wood, to how to glue the various boards, how to cover the connecting lines with strips of linen cloth (lining) how to treat and prepare them for painting with seven to eight coats of plaster and glue until they are reduced to the whiteness and smoothness of ivory (preparation). Great importance is given in the text to the stage of the preparatory drawing which is normally made separately and then transferred on the support according to one of the many traditional techniques. Already applied in this period and habitual in the early Renaissance is, for example, the pouncing system: it consists in using a drawing on paper, the outlines of which are pricked with an awl in order to allow the transfer of the drawing on the prepared panel, making a colored powder such as lampblack pass through the holes in the paper. The drawing is then perfected and retraced following this guide.
Having thus completed the figure, enriching it with a light watercolor shading, the outlines are engraved with a pointed iron (needle), identifying the areas to be saved for painting and those to be gilded. In the latter, after having spread the bole (more precisely the Armenian bole) as a background, gold leaf is applied (very thin sheets obtained from gold beaters), then polished, or burnished, using an animal tooth (burnisher).
With this operation, gold takes on a particularly warm, characteristic color, similar to that of bronze, hence the term burnishing.
At this point, we move on to coloring the panel, preferably starting, as Cennini recommends, with the clothes of the characters and the architecture, or in any case with the elements of the background. The colors, prepared in small containers in shades from dark to light, are always tempered with egg yolk (egg tempera) and spread by combination and fusion: “begin to spread the dark color, rediscovering the folds … and in the same way take the middle color and enhance the bumps and reliefs of the dark folds … then take the light color, and enhance the reliefs and bumps of the figure that catch the light. And in this same way go back to the first folds of the figure with the dark color. And so, as you started, goes over and over with these colors, now using one and now using the other”.
In the meantime, the decorative interventions (halos and backgrounds) are carried out on the golden surface, using a series of punches capable of impressing small motifs that are repeated according to a predisposed pattern.
The spreading of the skin tones, which, according to the rules of painting with Cennini’s egg tempera, is the final operation, requires a green base which, obtained with green earth and lead white, can let the underlying chiaroscuro design shine through.
After reinforcing the design with verdaccio, a rosy color (cinnabar and lead white) is then given on the cheeks and lips. The flesh color is obtained by starting the drafting by hatching, this time, from light to dark, blending the shades already prepared but always letting the “green below” shine through.
Manfredi Faldi – Claudio Paolini
Painting by Ulrika Alton
Estratto da: Artis (Art and Restoration Techniques Interactive Studio), Direzione scientifica: Manfredi Faldi, Claudio Paolini. Cd Rom realizzato da un gruppo di istituti di restauro europei, con il determinante contributo della Commissione Europea nell’ambito del programma d’azione INFO2000.
Quest’opera è distribuita con Licenza Creative Commons Attribuzione – Non commerciale – Condividi allo stesso modo 4.0 Internazionale.
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