July 1997 Issue 24
The Coronation of the Virgin - a Technical Study
The Coronation of the Virgin, CAI 104 (Figure 1)1, is attributed to Nardo di Cione, one of the leading artists of mid 14th century Florence. There is no surviving documentation on the panel and therefore the attribution and dating are based upon style. In July 1996 the Coronation was investigated using a range of techniques including examination by incident and raking light, stereo microscopy, x-radiography, infra-red reflectography and ultra-violet illumination (uv). Paint samples were also taken and examined2 . This paper presents the initial findings and highlights some of the interesting aspects of the panel's production. A subsequent paper will bring together technical, stylistic and iconographic evidence in the consideration of the panel's attribution and dating.
Nardo di Cione was one of four artistic brothers. Andrea di Cione, known as Orcagna, is the more renowned. Nardo matriculated in the Arte dei Medici e Speziali in Florence in 1343. He may have trained in the workshop of Bernardo Daddi and shared a workshop with one or more of his brothers at a later date. His best-known work is the Last Judgement, Paradise, and Hell cycle on the walls of the Strozzi Chapel in S. Maria Novella in Florence. As his will of 21st May 1365 was executed on 16th May 1366, he must have died by that date.
Structure, original size and shape of the panel
The panel is composed of three vertical butt-joined poplar members and measures 118 x 77.5 cm. The frame is 19th-century and has been applied to the surface of the panel edges reducing the sight-size to 110.5 x 70.5 cm. Two wooden butterfly joins are visible in the bottom half of the x-radiograph and must have been inserted to reinforce the joins (Figure 2). As they are not visible at all on the back of the panel, they must be part of its original construction (Figure 3). Although we now see the Coronation displayed as a single panel, it would originally have formed part of a multi-panelled altarpiece. Two marks and nail-holes on the back of the panel show where battens would have been attached to reinforce the joins in the panel and secure it to lateral panels at each side. The x-radiograph reveals the characteristic irregular shape of a medieval nail remaining in one of the holes. This indicates that the marks almost certainly correspond to the position of original battens.
Even as a single panel the Coronation is undoubtedly incomplete. As with many extant medieval works, it has been cut down, changing its original size and shape. There is physical and iconographic evidence for this. Proportionally, the panel looks wrong; the arch starts approximately half way up from the base. However, on other panels of the period the arch generally begins about two thirds of the way up from the base. The bottom batten mark on the back of the painting also appears too low relative to the base of the panel, as do the butterfly joins. Furthermore, in view of the panel's likely function as the centre panel of an altarpiece, its size would have had to accommodate lateral panels which might well have depicted full length saints. A study of the iconography in fourteenth century Italian panel painting indicates that the composition of the Coronation would have been unlikely to terminate just below the Virgin and Child but would have included another element. This need not have been musical angels as has been suggested, but perhaps a continuing expanse of the elaborate textile. Given the above evidence it is reasonable to conclude that the panel is missing a significant section from its bottom half.
As well as being cut down at the bottom, the shape of the panel may have been changed entirely. There is insufficient space to consider the arguements here, but again there is physical and iconographic evidence that the rounded arch may originally have been a rectangle, triangle or trapezium. The later inserts of a different timber at the 'shoulders' of the panel would have been applied after the panel was modified (Figure 4).
A combination of incised lines and punching has been used to decorate the haloes and the Virgin's crown. It is interesting to note that the haloes have been punched with a series of simple circular punches whereas more complex floral punches and a granular punch have been used for the crown. This discrepancy may reflect a simple desire on the part of the workshop to distinguish between the haloes and the crown. Alternatively, it may be that the punchwork was executed in two stages using two different sets of punch tools, not necessarily from the same workshop.
The panel includes various pentimenti - changes of mind - presumably on the part of the painter. The pentimento on the Virgin's profile is a particularly good example (Figure 5). Stereo microscopy revealed an additional incised line which was originally intended to be the outline of the Virgin's chin and mouth. This is very clear underneath her chin where the gilder has stippled up to the original line. The incised line curves upwards and protrudes approximately 5mm beyond the new painted line of the chin. It then curves in and out again forming the original line of the lips. This may reflect a decision made during the course of painting, to widen the gap between the bottom of the nose and top of the lips and to enlarge the chin.
Underdrawing and painting
Very faint lines of underdrawing are visible at the neck and waistline of the Christ figure where the paint layers have become transparent. These lines are scratchy and characteristic of a quill pen. Unfortunately, infra-red reflectography used to examine them further did not show any underdrawing. This does not necessarily mean that none is present, but simply that the underdrawing could have been executed with a material containing little or no carbon3 .
Paint samples were taken and made into cross-sections. These were analysed using incident illumination and incident polarised illumination at X100 to X500 magnification and with ultra-violet illumination at X250 magnification.
Christ's ultramarine robe:
A sample from just below Christ's hip revealed an underpaint composed of lead white, carbon (perhaps bone black), and a little dark red-brown ochre. This would have resulted in a purplish-grey tone which would deepen and enhance the blue of the ultramarine, a pigment of great translucency. A layer of unmodulated ultramarine has then been applied. The modelling has been achieved by black hatching in the shadows. The hatching is quite dense in parts, and consists of two types of lines. The majority of these are faint fluid lines which seem to be original. There are, however, some crudely executed thick black lines which are clearly not original as they extend over an area of paint loss.
The mordant gilding on Christ's robe:
A sample taken from the s-shaped fold on Christ's left side, (where the gold border overlaps slightly with the textile and the ermine lining of the robe), showed a trace of red bole over the gesso, followed by a layer of lead white. The adhesive used to affix the gold leaf includes lead white and brown ochre pigments. These have probably been added both to tint the oil size or 'mordant' and accelerate the drying process. The paint has split along both sides of the gold lines and, in places, across them. This is probably because the lead-containing, oil-based adhesive shrank, causing cracking of the gold leaf on top and of the paint layers below.
A sample was taken from underneath Christ's upper left arm. The extreme variation in tone on Christ's undergarment suggests the use of a lake pigment and some fading. The sample showed two layers of mid-toned pink paint which were probably executed with a mixture of two different types of red lake. One pigment fluoresced a bright orange-pink under uv illumination which is characteristic of madder lake; the other is probably of insect origin, such as kermes or lac.
The Virgin's robe:
A sample was taken from the right of the arrow-shaped shadow at the extreme left of the skirt. The true colour of the Virgin's robe is hidden by two layers of discoloured varnish. It would originally have been a very pale lilac colour and the cross-section showed that this was achieved by tinting lead white with azurite, madder lake and another lake which did not fluoresce under ultra-violet light4. This is a technique which Cennini mentions; 'And if you wish to clothe Our Lady with a purple, make the drapery white, shaded with a little violet so very light that it is just off white.' 5
The mordant gilding on the Virgin's robe:
A sample taken from the left fold at the foot of the robe again revealed an oil size tinted with ochre but in this case it seems to contain little, if any, lead white. This may explain why the gold leaf has not split.
The lining of the Virgin's robe:
Of the three samples taken, one was from below the Virgin's right elbow and another from where the lining is visible on her shoulder. The lining now appears black, but was actually once a bright green with a raised black floral pattern. The pattern is visible in raking light and shows up very clearly with infra-red reflectography. A sample taken from the pattern on the lining showed a complex layer structure. Silver leaf has been applied on top of the gesso ground with an oil size tinted with ochre. This has then been glazed with what seems to be a verdigris layer and two coats of clear green copper resinate or oleate glaze. A sample taken through one of the lines of the floral pattern showed that this is composed of a mixture of lead white and carbon black. A layer of copper resinate or oleate glaze was also identified on the border of the Virgin's crown.
Flesh tone of the Virgin's hand:
A sample taken from the Virgin's left hand, just above her wrist, shows the typical technique for painting flesh at the time. The underpaint of the flesh is composed of green earth, lead white and a little yellow lake. Verdaccio consisting of vermilion, a little carbon black and possibly lead white has been applied to the areas of shadow. The layer of pink flesh colour has been obtained by mixing lead white and vermilion.
The samples taken from Christ's blue robe and from the Virgin's lining revealed a faint, grey layer over the final pigment layer which may represent an earlier or original egg white glair applied to protect the surface. It is also evident that the Coronation had been varnished at least twice with an oil varnish.
Overall the pigment analysis suggests that a great deal of colour change has taken place on the Coronation affecting the brilliance of the panel. The pigments used are typical of the works of the di Cione brothers and indeed of paintings of the period.
The examinations of the Coronation of the Virgin as a whole give a valuable insight into the production of this type of work. They are also useful in piecing together the original appearance of works of this period.
2. The pigment results are a summary of Jo Darrah's findings: An Examination of the Materials and Techniques of the Coronation of the Virgin, Internal V&A Conservation Research Report, September 1996.
5. Cennino d'Andrea Cennini, The Craftsman's Handbook 'Il Libro Dell'Arte', Dover, 1960, p93.