Cosimo Tura as Painter and Draughtsman: The Cleaning and Examination of his ‘Saint Jerome’

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National Gallery Technical Bulletin Volume 15, 1994

Cosimo Tura as Painter and Draughtsman: The Cleaning and Examination of his ‘Saint Jerome’

Jill Dunkerton

As court painter first to Borso and then to Ercole d'Este, Dukes of Ferrara, Cosimo Tura was called upon to produce not only paintings, but also designs for the luxurious trappines – from tapestries and wedding dresses to tournament harnesses and silver table services – of one of the most extravagant courts of fifteenth-century Europe (note 1). He must have supplied the makers of these artefacts with countless sketches and drawings, yet only three drawings on paper generally accepted as by Tura have been identified (note 2). To extend our knowledge of Tura's style and technique as a draughtsman it is necessary to turn to his paintings. Infra-red methods of examination have shown that a bold and detailed underdrawing is an invariable feature of the paintings by him examined to date (note 3). In many of them an increase in transparency of the paint layers with age has made much of the underdrawing visible to the naked eye. In the case of the ‘Saint Jerome’ in the National Gallery (Fig. 1 and Plate 2) an unusually detailed underdrawing has long been evident in some areas, but it needed a full photographic and scientific examination, made as a standard part of the process of cleaning and restoration, to reveal that the underdrawing is as remarkable for its technique as for its extent.

The panel was bought by the National Gallery in 1867 from the widow of Sir Charles Eastlake as one of the group of paintings from Eastlake's own collection acquired while he was Director (note 4). Like many of the Ferrarese paintings in the National Gallery, the ‘Saint Jerome’ came from the Costabili Collection in Ferrara, where Eastlake and his travelling agent, Otto Mündler, first noted it in 1858. Neither mentions its specific condition but Mündler comments on the generally neglected state of the collection (note 5), and when in 1860 Eastlake bought the panel as part of a package insisted upon by the Conte Costabili before he would part with ‘The Virgin and Child with Saints George and Anthony Abbot’ by Pisanello (NG 776), it was immediately sent, with the Pisanello and the other painting, another ‘Saint Jerome’ by Bono da Ferrara (NG 771), to Giuseppe Molteni, the leading Milanese restorer. Molteni, who restored many of Eastlake's Italian purchases, both for his private collection and for the National Gallery, welcomed the work because, as he told his friend Giovanni Morelli in a letter, 'it will procure me the knowledge of three new painters whom I have never seen before' (note 6).
Although the National Gallery manuscript catalogue records a cleaning and varnishing of Tura's ‘Saint Jerome’ in 1881, this can only have comprised a surface cleaning, or at the most the removal of an artificial toning (note 7): the appearance of the painting before the recent treatment had every characteristic of a restoration executed by Molteni. With time, his varnishes, whether deliberately tinted or not, tend to discolour to a greenish-brown, almost olive, hue, while his retouchings often blanch to a silvery-grey colour (Plate 1) and in the glazes lose the transparency which they presumably originally possessed. They can also be transparent to infra-red, so infra-red methods of examination, when used in conjunction with other diagnostic techniques such as X-radiography, sometimes supply useful information on the condition of the underlying original paint. For example, on the ‘Saint Jerome’ infra-red photography (Fig. 2) penetrated the retouchings sufficiently to show that while some parts of the painting, such as the head of the saint, were almost perfectly preserved, other areas, particularly in the lower part of the picture, had suffered from abrasion and extensive fine flaking. Along the lower edge the paint and ground had flaked away completely, the vermilion of the retouchings on the cardinal's hat having blackened while that of the original paint had retained its colour. In addition, long diagonal bands of damage were visible in both the infra-red and X-ray photographs (Fig. 3) where the surface seems to have been splashed with a corrosive substance, perhaps candle wax or a cleaning material, or possibly bird or bat droppings which can eat into a paint film if not immediately removed.
Molteni, however, did more than just touch out these losses. As in so many of his restorations for the National Gallery, and for other owners and institutions, he made several adjustments and 'corrections' to the painting (note 8). Some were quite subtle: for example, the general softening and rounding of Tura's characteristically angular modelling of the drapery folds and the suppression of the fine highlights along the outer edges of the folds on the side of the figure in shadow – a form of secondary backlighting again typical of the painter. Other changes were even less justifiable. For no apparent reason the columnar folds of drapery which hang down from the saint's left elbow were revised, while his raised arm was slightly widened, presumably because it was considered unacceptably lean and sinewy (Plate 1). This enlargement of the outline continued down the folds of the habit draped across his upper arm and shoulder, filling in the space between them and his beard and throat. This space, in itself a pleasing configuration of overlapping forms, is important in that it emphasises the three-dimensional qualities of the figure. Further down, the saint's sharp bony knee was shortened and made more rounded, while in restoring the damaged lower edge Molteni eliminated the plant in the foreground altogether.

In the landscape the rocky outcrops on the left were glazed to reduce the strange, but perhaps significant, geological difference between the pale grey stone to the left of the tree and the deep purple-red of the cliffs to its right, and the distant mountains were reinforced, spoiling Tura's intended effect of aerial perspective. In the sky the arc of light was painted out, although it remained just visible, allowing Martin Davies to establish correctly the original position of the fragment cut from the panel showing ‘Christ Crucified’, now in the Brera, Milan (Figs. 4 and 5) (note 9).

That little was lost in the sawing of the panel is confirmed by the presence of a small green bush at the bottom edge of the Milan fragment. This originally topped the pinnacle of rock in the ‘Saint Jerome’ where similar bushes are now visible but had been touched out by Molteni. It has sometimes been suggested that the composition of the ‘Saint Jerome’ panel was also reduced at the left and possibly the right edges (note 10). The wood of the panel has indeed been trimmed, but there is a definite raised lip or 'barbe' of gesso down the right edge and a slightly elevated edge to the gesso along the left edge, suggesting that a similar 'barbe' was present and that the panel may once have had a frame moulding attached to the front edges. In addition, the fact that the panel consists of a single board of close to the largest width commonly found in planks of poplar, suggests that the work always had this tall narrow format. If it had been any wider, joins in the panel would have been required.
A clue to the possible date of the removal of the Milan fragment was discovered during the cleaning of ‘Saint Jerome’. Molteni's varnish and retouchings were both readily dissolved, as is usually the case with his restorations, in the same solvent (in this instance acetone). Underneath were the remains of a thin and streaky application of an older varnish layer. This varnish, which was of an unusually hot, red-brown colour, was evidently not original since it covered many of the losses, and runs and dribbles could be seen down the trimmed right edge of the panel. Analysis of a sample by GC-MS showed it to be based on an African copal, probably a Congo copal, in linseed oil, and possibly pigmented with aloes or a similar dyestuff. It is unlikely to date from before the early nineteenth century (note 11). Since brushmarked streaks of the same varnish are clearly visible on the ‘Christ Crucified’ (not cleaned at the time of writing) it was evidently still attached to the ‘Saint Jerome’ when this varnish was applied. Therefore, it seems probable that the painting was mutilated at some point between about 1783, when it was seen – and described as 'an elongated panel' – in the Rizzoni Collection, Ferrara (note 12), and 1836, by which date the ‘Saint Jerome’ was in the Costabili Collection. The Milan fragment has suffered the same forms of damage, including the splashes of corrosive liquid, as the National Gallery painting, but, as it passed through different collections in the mid- and later nineteenth century (note 13), it seems to have escaped the attentions of Molteni.
The condition of the ‘Saint Jerome’ following the removal of the old varnishes and restoration (Fig. 6) was highly informative in assessing Tura's technique. Because much of the damage consists of flaking and abrasion to the upper paint layers rather than total loss, in many areas the broad hatched lines of black underdrawing were exposed. More unexpected was the discovery of fine lines of lead white paint used to highlight the underdrawing (Plate 3). For these lines to register, Tura could not have been working on a pure white gesso ground. The areas of gesso exposed by damage have a warm golden colour but often this is attributable to the discoloration with age of the glue in the gesso, especially if a high proportion of glue is present. While samples indicate that the ground is indeed rich in glue, several cross-sections also include a layer of yellow-brown paint, consisting of a mixture of carbon black and yellow ochre with possibly also a little yellow lake, applied over the ground, and, in one sample, over the lines of black underdrawing (Plate 4). Confirmation that this layer is not an overall ‘imprimatura’ employed to reduce the whiteness of the ground is provided by its absence from samples taken from the flat areas of pale green grass (mainly malachite with varying amounts of lead white and lead-tin yellow) and from the sky (which has a layer structure of ultramarine and white over an under-paint of azurite and white, a feature common to many paintings of this period) (note 14).
The distribution and function of this yellow-brown layer only become apparent in the computer-assembled infra-red reflectograms. These were recorded after the restoration, since unretouched areas of loss tend to register as white, causing difficulties in imaging (Fig. 7) (note 15). As well as revealing even more underdrawing of the conventional linear and hatched type, and with greater clarity than in infra-red photographs, the reflectograms show that Tura reinforced the already sculptural properties of his drawing by the use of broad washes of monochrome undermodelling. Since it is the black component of the pigment mixture used for the undermodelling that registers in infra-red, the image formed by the washes is best separated from that resulting from the overlying paint layers in those areas with little or no black pigment, that is, in the flesh tones of the main figure and, more particularly, in the robe of the donor figure on the right, which is painted with red lake and therefore virtually transparent to infra-red radiation (Plate 3 and Fig. 8).
This use of monochrome undermodelling to define the volume and lighting of figures is more commonly associated with the paintings of Leonardo da Vinci, and subsequently with sixteenth-century painting. A brown underlayer can be seen in areas of flesh painting in the later, oil-based paintings of Piero della Francesca, but the modelling, if there is any (note 16), does not seem nearly as well developed as that of Tura in the ‘Saint Jerome’. While the use of wash drawing is not uncommon in works on paper by the mid-fifteenth century, it is possible that its appearance here on a panel is in some way connected with the influence on Tura's painting method of artists from Northern Europe. It is probably not a coincidence that brown or grey-brown layers applied over the ground and underdrawing are reported on paintings associated with the workshops of Rogier van der Weyden and, before him, of Robert Campin, including ‘The Virgin and Child before a Firescreen’ discussed in this ‘Bulletin’ (see pp. 21–35).
What does seem peculiar to Tura is the use in an underdrawing of highlights of lead white, applied mainly to the edges of forms, but sometimes also in small areas of hatching to indicate broader areas of light, for example in the hollowed-out folds across the saint's knee and thigh. Similar hatched strokes of white highlighting have been noted on his ‘Allegorical Figure’ (NG 3070) and can be seen in X-radiographs, or sometimes on the damaged surface, of certain other works (note 17). Inevitably, in X-radiographs the lines of white underdrawing can be difficult to distinguish from lead-white based highlights in the paint layers above, but a pentimento in the ‘Saint Jerome’ gives a good indication of the extent of the highlighting. Originally the barn owl with the frog was placed to the left of its present position: it is now superimposed over the completed painting of the bark of the tree. In infra-red light the black underdrawing of the owl in its first position can barely be detected because of the amount of black pigment in the overlying paint, but in the X-radiograph (Fig. 9) the underdrawn owl is readily visible, entirely because of Tura's use of white highlights.
To get some idea of the appearance of the ‘Saint Jerome’ before the application of the paint layers, one can turn to the damaged and retouched, yet still astonishingly vigorous, pen and brush drawing on ochre-tinted paper of ‘Hercules and the Nemean Lion’ in Rotterdam (Fig. 10) (note 18). In this drawing there are the same bold black outlines and strokes of parallel hatching which follow round the forms like the drawings of a sculptor, the broader washes – and some shading with black chalk – to further emphasise volume and to establish shadow, and then finally the linear and hatched highlights of white.
It has been suggested recently (note 19) that this drawing is close in date to the organ shutters with the ‘Annunciation’ and ‘Saint George and the Dragon’ painted by Tura in 1469 for the cathedral of Ferrara. Following the cleaning of the ‘Saint Jerome’, there are reasons to believe that it too may date from this period and therefore be earlier than previously thought (note 20). The landscapes in the ‘Saint Jerome’ and the ‘Annunciation’, with their zig-zagging vertical construction and pale green grass, have much in common. The draperies of the saint and the pose with one knee raised – unusual among Jeromes of the fifteenth century – can be related to those of the Virgin and the Angel, while the musculature of his undraped torso can be compared with the representations of relief sculptures on the side walls in the ‘Annunciation’. The technique of the flesh painting, where lighter areas are underpainted with a pale warm grey and then scumbled with the thinnest of applications of colour - in the case of ‘Saint Jerome’, lead white tinted with red lake - appears to be the same (note 21). A similar layer structure occurs in the flesh tones of the ‘Allegorical Figure’, possibly Tura's earliest surviving work, but not, for example, in ‘The Virgin and Child Enthroned’ (NG 772) from the Roverella Altarpiece and ‘The Virgin Annunciate’ (NG 905), both thought to date from the mid-1470s or later.
Although the technique and damaged condition of the organ shutters means that their colour is now generally muted, they share with the ‘Saint Jerome’ a particular use of local touches of the bright red pigment vermilion. On the shutters it is applied to certain details, mainly, it would seem, for decorative purposes, for example in the harness of Saint George's horse; but on the ‘Saint Jerome’ the vermilion, which is by far the brightest colour in the painting, is used to draw the eye of the viewer into the painting, from the cardinal's hat and the books in the foreground to the small but not-to-be-overlooked figure of the donor in the background. The importance of the donor is further emphasised by the fact that when the fragment showing ‘Christ Crucified’ is in place (Fig. 5) it becomes evident that the donor and the cowled figure presenting him are looking up at the vision of the Crucifix, while the saint seems almost more absorbed in penitential devotion.
In the first known description of the painting, that of 1783, the donor is identified as Borso d'Este (note 22). While this association of Borso with the painting has sometimes been repeated (note 23), the figure of the donor bears no resemblance to portraits of him, least of all in its sobriety (by Borso's standards) of dress. Unfortunately the face is badly damaged. In restoring the painting, the areas of complete loss were toned in, but no attempt was made to reconstruct the features for fear of prejudicing any future identification of the portrait. Nevertheless it is worth pointing out that even in its damaged condition the head – short-haired and apparently balding, with a long, hollow-cheeked face and distinctive bumpy nose – resembles that of the similarly costumed figure standing to the left of Borso in the lower section of the fresco of the Month of April in the Palazzo Schifanoia (note 24).
The donor is presented by a monk – perhaps also a portrait – who wears the habit possibly of a Franciscan, or more probably of one of the Hieronymite congregations (note 25). Saint Jerome himself wears the outer mantle of a habit (the front panel of which is thrown back over his left arm) rather than the customary tunic or hair shirt. Similarly robed friars, but more like conventional Franciscans, carry building materials up the paths to the magnificent Albertian church on the left. This may refer to Jerome's title as one of the Fathers of Church rather than to any actual church under construction at the time. The church façade is carefully underdrawn whereas the figures are later additions, thinly painted over the completed landscape. Also added are the bird on the left, an accurate depiction of a wall-creeper, inhabitant of wild and rocky places, and the frog – now discoloured but once a rich 'copper resinate' green – which does not feature in the first, white-highlighted drawing of the owl (Fig. 9) (note 26).
In a painting so rich in detail and allusion much remains to be explained, not least the replacement of the saint's traditional rocky cave with the hollowed out, almost petrified tree. The boldness of this invention is now diminished by the panel having been cut, but the design makes it improbable that the work was ever part of a larger complex of panels. Therefore to questions about its patron, date and provenance should be added those concerning its original function, whether it was ever intended for a church (note 27) or whether it was for private devotion. While much remains unanswered one can only conclude, like Cesare Cittadella in 1783, that Tura's work is as 'bizarra, ed erudita' as it is 'diligentissima' in execution (note 28).

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