In 1972 I was entrusted with the task of restoring the picture »The Adoration of the Shepherds« belonging to Prague Castle. It had the inventory number OPH 165 and was registered as »work by an unknown master of the middle of the 18th century« During long years of research and restoration (until 1979) all later bonding agents and overpaintings were removed. As a result the work was attributed to Jacopo Tintoretto as his authentic work. The purpose of this brief paper is to give an outline of the research into the technological structure of the picture and the conclusions reached by comparing it with analyses of well-known and established works of Tintoretto.

The canvas of the picture is made of linen, is roughly woven with a density of 10x10 threads to the square cm. It is sewn out of two strips with a horizontal seam that divides the picture above the middle and drops by 5° towards the right-hand edge. The original width of the canvas cannot be precisely determined since the picture was truncated along the edge. (At that period the width of canvas in Venice ranged from 100 to 120 cm).

The priming is formed of thin gesso (a layer of burnt gypsum mixed with size). Along the surface it is saturated with oil that has soaked from the paint. The average thickness of the layer is 0.111 mm (0.53-0.29 mm).

Underpainting: On the priming there appears an uneven layer of charcoal black; the thickness of this layer averages 0.018 mm (ranging from 0.004 to 0.076 mm according to whether the sample included only the design drawing or the underpainting). The second layer of under-painting in lead white likewise shows variable thickness in different samples averaging 0.054 mm (0.018-0.106 mm). It is absent in five samples.

Joyce Plester s and Lorenzo Lavarmi 2 wrote an extensive work describing their research into 10 pictures by Tintoretto. From this I have deduced that, at the beginning, he used black preliminary drawing on a light gypsum ground and later underpainting carried out in oil charcoa black with lead white for modelling, between the years 1556 and 1566 imprimatura in brown to black gradually grew in importance which made it possible to build volumes with thick lead white and change the. entire system of underpainting. In those years two parallel systems appeared side by side. In 1578, which is the year when the picture »The Origin of the Milky Way« came into being, there began to appear a dark-brown ground coloured in full strength and formed by a thin coat j of charcoal black and brown ochre bonded with oil. This system enabled Tintoretto to simplify the underpainting and to speed up the further construction of the picture on a dark priming, which suited his temperament and the need to carry out rather large canvases (e.g. »The Last Judgement« – 14.5x5.8 m).

Knowing these facts it becomes clear that this picture is a kind of interim stage between the system with a black preparatory drawing on a white priming and a white drawing on a dark priming, that is, around 1550 when the broadly conceived dark drawing merges into the underpainting and in identical f unction as the later dark grounds lay under the white modelling built up in drawing. Some contours in black paint were used f or the deep modelling shadows in the final form of the work just as certain divided thick strokes in white in the underpainting were finished simply with a glaze. The system of treatment of the underpainting of »The Adoration of the Shepherds« is quite typical of and unique for Jacopo Tintoretto an is fully identical to published analyses of works by that master 6. We should recall here Tintoretto's statement that he regarded black and white as the most beautiful of colours: Black since it gives the figures strength, deepens the shadows and white because it gives them relief."

The Adoration of the Shepherds – right-hand side of the picture, condition after restoration


Likewise the pentimenti (the change in the inclination of the head of the Virgin, the right hand of the old man and others) speak for the thesis that Tintoretto in person worked out the composition of this picture in the drawing and oil underpainting directly on the canvas. The lively brushwork of the underpainting was then intentionally calmed by the manner in the surface layers.

The pigments were identified on cross-sections of the paint with the aid of a microscope; all of them are typical of Venetian painting in the 16th century. All layers contain lead white, charcoal black and earths. In the layers of paint can be found also cobalt glass (smalt), azurite, malachite} copper resinate, vermilion, ker mesie dyestuff coagulated on a substrate of alluminium hydroxide, auripigment, realgar, lead-tin yellow and occasionally, lamp black. My microscopic evaluation of the cross-sections was confirmed by microchemical analysis of all main pigments, histochemical analysis of binding media and Chromatographie determination of carmine carried out by Dr J. Tomek and D. Pechová of the National Gallery in Prague, to whom I am endebted. The only exceptions were azurite, vermilion, lead-tin yellow and lam black, which were evalued only by visual comparison.

The medium of pigments is linseed oil even though an admixture of natural resin cannot be ruled out.

The painting is composed of two to eight full and transparent layers of paint placea one on top of the other, mixed of several pigments in each layer. This very system of creating one tone by means of the compilation of several layers of paint generally sets the picture into the circle of 16th century Venetian painting.


  author
doc. Karel Stretti, AHVT B 015, C 011 (T. G.)