Van Eyck – The technique
The oil painting technique, once believed to be an invention by the Van Eyck brothers, was actually already known by the ancient Romans who had experimented with oily binders to paint shields and weapons. The technique is also mentioned in the “Schedula” of monk Theophilus (XI Century) and also by Cennino Cennini (end of XIV Century). In any case, it was the Flemish painters who, in the first half of the Fifteenth Century, began to systematically experiment with oleo-resinous mixtures, developing a new working method that they would soon adopt almost exclusively.
Flemish painting of the Fifteenth Century is characterized by a limpid and glazed matter obtained by successive superimpositions of thin mixtures. The oil binder allows to obtain a fluid material facilitating the application of glazes. The slow drying of the colors also allows very soft shades and the chromatic range can thus be expanded thanks to the play of transparencies obtained by overlapping different colors.
Van Eyck is certainly the most representative of Flemish painting of the early Fifteenth Century. He applies a rigorous technique whose principles are integrated into a tradition that already made extensive use of glazes spread on opaque backgrounds modeled in chiaroscuro. The technical innovation, on the other hand, can be found in its making the most of the light reflection of the bright ground preparation, obtained with two or three thin layers of white gypsum and animal glue, smoothed with great care. The design (usually made with bone black diluted in a water-based binder) is traced on the preparation in order to place the shapes and define their contours. Often it is a linear and summary drawing, basically a sketch with sparse modeling indications, other times it is instead executed so scrupulously that it already announces the final effect. All the details are represented with the same definition and the model is built with light and progressive transitions from shadow to light, obtained with a fine hatching.
This drawing is covered by an intermediate layer of drying oil in order to prevent the preparation from absorbing the binder contained in the subsequent layers of color, and to allow these to keep all their splendor intact. In addition to a waterproofing function, this light layer of primer also performs an optical function when, instead of being translucent and colorless, it is slightly tinted. By operating in this way, the final effect of the colors that will then be superimposed is obtained. Sometimes primers of different colors are used in this phase to prepare the chromatic distribution of the main planes of the composition.
With colors as pure as possible, distributed in thin layers and with a small amount of lead white, the painter now constructs the modeling of the complexions and all forms.
Through these successive layers, the former relatively opaque and the latter crystalline, the complete structure of the painting is thus achieved before the application of the glazes.
A variable number of successive layers can sometimes be better defined with a slight chiaroscuro. The colors ground with oil and hard resins and diluted with essential oils allow, in addition to a slower processing for the shades, also a fine and minute touch. The lights are generally obtained by exploiting the effect of brightness given by the ground preparation applied to the wood panel, however the maximum lights are often applied as full-body brushstrokes. In other words, from a watercolor sketch we arrive at a more consistent draft only in the light tones, an executive process that will be subverted by the canons of Italian painting where a sketch with full-body colors will be finished by means of glazes.
This basic covering layer, which ensures solidity to the masses, is now enriched by numerous overlaps of translucent layers, real glazes that create the effect of volume by modulating the underlying shapes.
The transparent pigments such as the garanza lake (in order to make the most of the light reflection on the white background), are distributed in successive glazes until they reach a certain relief in the darker areas: the shadows obtained are extremely sweet, deep and transparent.
The binder used varies according to the colors. Three different types have been detected:
1. water-based binder for the execution of the first design phases and for the application of pure natural ultramarine blue;
2. emulsion of drying oil and egg in variable proportions in the covering layers;
3. fatty binder composed of oil and / or natural resin in some glazes to obtain more transparent whites.
It is assumed that Van Eyck already used essential oils that he himself would have managed to distill, as evidenced by the refined execution of the details that only a fluid and flowing film can allow.
Finally, the bright paint strokes given “a corpo” are performed on the maximum lights with pure lead white. The result is a transparent and luminous material, especially in the complexions, a sense of uniformity and enveloping light but also finesse in the execution of the details that are at the same time evocative of space and perfectly fused into the environment.
In other words, we are witnessing a perfect interdependence between technique and style: the analytical representation of reality, investigated in detail and considered a distinctive sign of Flemish painting at this chronological height, turns out to be possible only thanks to precise technical expedients, linked to its use of oily binders and a pictorial execution in which the shapes are determined by thin and liquid layers.
Manfredi Faldi – Claudio Paolini
Painting by Francesca Berni
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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