Initials from Choir Books

Differences in palette

Artists' Materials

These same two initials, as well as the St Laurence, also contain a dark red earth pigment which was used to outline the glittering bronze-coloured decorations painted in mosaic gold. All three are characterised by the use of a yellow lead oxide, which was also mixed with azurite to provide green hues.

The yellow initial D surrounding St Clement, however, was painted with lead-tin yellow. This pigment characterises the palette of Christ the Redeemer where it also appears mixed with azurite in green areas.

The image of Christ is unique also for the presence of a purple hue, obtained with an insect-based dye, as well as for the use of umber in the darkest portions of Christ’s flesh tones and of yellow ochre to provide highlights in his hair.

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Detail of the green decoration over the orange book under magnification (60x), which blue and yellow particles clearly visible. The high amount of copper (Cu) and lead (Pb) recorded in the XRF spectrum (below) support the identification of azurite blue and a lead oxide yellow.
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Detail of the darkened yellow initial under magnification (20x), and XRF spectrum (below) showing the combined presence of lead (Pb) and (Sn), typical of lead-tin yellow.
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Detail of flower-shaped stamp impressions in the lower border, acquired under magnification (12.5x) using raking light.
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Detail of flower-shaped stamp impressions in the lower border, acquired under magnification (12.5x) using raking light. In this case, a flower-shaped portion of brown cardboard is still extant, likely having remained stuck to the ink note visible just underneath it, when the rest of the board was removed.
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Detail of St Clement’s white robe under magnification (60x). Numerous blue particles can be seen and identified as ultramarine by a small peak at 539 cm<sup>-1</sup> in the Raman spectrum (below). The more intense peak at 1050 cmcm<sup>-1</sup> is characteristic of lead white.

Historiated initial D from a Gradual, 1370-1375

The initial D opened the Mass for St Clement’s feast (23 November) in Corale 2, a Gradual made in 1370-1375 and illuminated by Don Silvestro dei Gherarducci. The individualised physiognomy, emulating the facial types of Simone Martini and paralleled in works by his followers, demonstrates Don Silvestro’s familiarity with Sienese painting.

Typically Florentine, however, is the use of a mixture of blue and yellow to obtain green, while in Siena artists favoured the green copper mineral malachite. Here, azurite blue was probably mixed with a lead oxide yellow (hotspot 1). This same pigment was also used in the yellow highlights over the green leaves and in the book held by the Saint. The yellow initial, however, was painted with lead-tin yellow, as can be seen by selecting the elemental map for tin (Sn, layer ‘elemental map Sn’). The same map also shows that a small section of the blue mantle’s gilded border was painted with mosaic gold (tin sulphide), perhaps as an afterthought. Mosaic gold was also used for the small yellow dots which decorate the mantle, and for the shiny ornaments and leaf outlined in a dark red iron oxide pigment (Fe, layer ‘elemental map Fe’).

The pink leaves and the yellow initial, as well as the white highlights over the orange leaves and ornaments, have darkened significantly (hotspot 2). This is most likely linked to the presence of lead white. In the pink and yellow areas the discoloration appears to have started not on the surface but rather in the lower portion of the paint layers. If this is indeed the case, the degradation process may have been catalysed by the materials used to glue the fragment to its modern cardboard support.

Microscope images acquired in raking light provide evidence of the previous existence on the front side of the image of a brown cardboard mat, stamped with flowers and other decorative elements, similar to the one still visible around the Presentation in the Temple. The impressions left by these flowers are still visible especially along the lower edge of the fragment (hotspots 3 and 4).