National Gallery Technical Bulletin Volume 19, 1998

The Restoration of Peyron's ‘Belisarius’ and ‘Cornelia’

Larry Keith

The two recently acquired oil sketches by Pierre Peyron, ‘Belisarius receiving Hospitality from a Peasant’ (NG 6551), painted on paper mounted onto canvas, and ‘Cornelia, Mother of the Gracchi’ (NG 6552), on canvas, are the first paintings by this artist to enter the Collection, and have made an important addition to the Gallery's early neo-classical holdings.

The pictures represent an intermediate stage in Peyron's working process between the numerous preparatory drawing stages and two finalised larger paintings of the same subjects now in the Musée des Augustins in Toulouse, and may be the same pair recorded as having been exhibited in the 1785 Paris Salon (note 1). From a conservation point of view they were remarkable for their relatively untouched state, with at least one of the pictures displaying what could well be Peyron's own retouching over an original varnish. The eventual approach taken for the cleaning of the paintings provides an excellent example of scientific analysis informing sound conservation practice.

Because of the fragile state in which they arrived at the National Gallery, both the ‘Belisarius’ and the ‘Cornelia’ were sent to the Conservation Department on acquisition, where they were treated between July 1995 and March 1996. While the two pictures show marked differences in paint handling – largely as a consequence of their different supports – both paintings involve essentially the same materials and layer structure. Each was painted in partially heat-bodied linseed oil and had two distinct surface coatings, the earlier of which in both cases may well have been applied by the artist.

Although the ‘Cornelia’ had certainly been restored and revarnished as a result of local damages and subsequent flaking, it appears possible that both it and the ‘Belisarius’, which also had been revarnished in the same way, may never have been cleaned (note 2). Their similar varnish layer structure, which implies a common conservation history, reinforces the impression of their long-term association.

‘Belisarius receiving Hospitality from a Peasant’

The picture was cleaned with mixtures of isopropyl alcohol (propan-2-ol) and white spirit, which allowed the uppermost varnish layer to be easily separated from a resin-containing layer below it. This lower varnish layer had a markedly stronger fluorescence in ultra-violet light than did the top layer, probably as a result of an accumulation of dirt on the upper surface diminishing its own fluorescence. Medium analyses of the two layers showed the uppermost to consist of linseed oil with pine resin, with the lower varnish layer composed of pine resin and mastic resin, possibly with a little linseed oil added (note 3). The weaker fluorescence of the upper varnish layer suggests a low resin content; however, this varnish layer was nonetheless considerably discoloured and hazy, and its removal brought noticeable aesthetic improvement.

The lower varnish layer was left undisturbed. This layer was not itself markedly discoloured or broken up, and its removal would have made little visible difference. More important, some final brushstrokes – for example, the adjustment of the right contour of the basket interior at the lower left of the picture – appeared in UV examination to be on top of this layer. These brushstrokes appeared similar in every other way to those of the rest of the picture, and therefore the possibility that Peyron had himself made these final adjustments on top of his varnish could not be excluded (note 4).

As it could not be proved that the paper and canvas assembly was not original, and as the painting was still generally in good physical condition, it was decided to repair rather than replace the old secondary canvas support. Loose edges and local damages of the paper were re-attached to the canvas using wheat starch paste. The paper and canvas assembly was then treated repeatedly with moisture and humidity on the low-pressure table to improve surface irregularities. Additional localised treatment with moisture, weights and heated spatula was applied to some smaller deformations. After strengthening the tacking edges with a fine-weave polyester fabric, which was attached using Beva 371 adhesive, the picture was stretched over a Beva-primed linen loose lining onto a new, purpose-built stretcher.

The picture was then brush-varnished with ketone resin, since dammar was considered unsuitable given the resinous composition of the preserved old varnish layer. The retouching was largely confined to the suppression of staining from flyspots, and was carried out in dry powdered pigments in Paraloid B-72, with some darker glazes retouched using ketone varnish medium.

‘Cornelia, Mother of the Gracchi’

As in the ‘Belisarius’, two separable coating layers above the paint layers were identified on the ‘Cornelia’, the lower of which exhibited comparatively stronger fluorescence. The upper layer was again identified as linseed oil with pine resin, while the lower layer was identified as a mixture of pine resin and mastic resin, possibly with a little linseed oil added (note 5). Although there were no signs of Peyron reworking on top of the lower varnish layer, it was nonetheless left intact as on the ‘Belisarius’, and only the uppermost, highly discoloured varnish layer was removed with mixtures of isopropyl alcohol and white spirit.

The canvas had four major local damages with associated cardboard patches glued to the reverse, which were clearly visible in the X-radiograph. All the associated repaints, although apparently quite old since they were under the upper varnish layer, were found to contain pigment mixtures not typical of the late eighteenth century, including one pigment, viridian (transparent chromium oxide green), introduced after Peyron's death; the repairs were therefore clearly not the artist's (note 6). They were fairly crude in execution, and in some cases were painted directly onto the card used to repair the losses in the canvas. Removal of later grey repaint coarsely applied around the flake losses in the lower left corner revealed an incomplete signature and date: ‘P. Peyron f. (...) 1781’.

The cardboard patches, which had been affixed with lead white paint, were scraped away from the reverse. Replacement canvas inserts of a similar weave were fitted into the losses in the support, glued with PVA and further reinforced with a fine net-weave synthetic fabric (Stabiltex) attached to the reverse with Beva adhesive. After local blister treatment with isinglass (sturgeon glue) adhesive, the canvas was given repeated moisture treatments on the low-pressure table to reduce the overall raised pattern of craquelure. The tacking edges were then reinforced with a fine-weave polyester fabric, which was attached using Beva 371, after which the picture was stretched over a Beva-primed linen loose lining onto a purpose-built, keyable blind stretcher.

The picture was then brush-varnished with ketone resin, losses filled with a PVA-based chalk filling, and then retouched using dry powdered pigments in Paraloid B-72. The previous repair of the damage through Cornelia's right arm and hand featured a reconstruction where the curved-up index finger was erroneously turned into the thumb; the recent restoration has been based on the gesture found in Peyron's final version of the composition, now in Toulouse.

Notes and references

1. For further information on the documentation, provenance, critical history and technique, see Humphrey Wine, Two paintings by Peyron at the National Gallery', ‘The Burlington Magazine’, CXXXIX, 1997, pp. 248–55.
2. The medium analyses of both paint and varnish layers were carried out by Raymond White and Jennifer Pilc of the Scientific Department, using FTIR-microscopy and GC-MS analysis. Further study of the effects of cleaning on the paint film has been undertaken by Raymond White and Ashok Roy as part of a larger study of solvent cleaning, to be published in due course.
3. The upper layer was identified as linseed oil with pine resin by GC-MS, with FTIR analysis suggesting imbibed dust trapped in the upper surface, which could account for the quenched fluorescence.
4. For a survey of French academic varnishing practice, see Michael Swicklik, 'French Painting and the Use of Varnish, 1750–1900', ‘Conservation Research: Studies in the History of Art, 41, Monograph Series II’, National Gallery of Art (Washington), 1993, pp. 157–71.
5. Identified by GC-MS analysis and FTIR-microscopy.
6. Viridian was identified in a variety of pigment mixtures, including flesh tones of the arm, the darker tones of the reconstructed orange drapery, and the brown repaint applied over and around damages in the background. First described in the early 1830s (Peyron died in 1814), viridian may have been used first in the mid- to late 1820s, but was initially a very expensive pigment; it is unlikely to have been employed in such mixtures where its qualities as a transparent glazing green would not have been exploited. Identification of pigments was made through EDX analysis of prepared cross-sections by Marika Spring of the Scientific Department, who also provided invaluable assistance in the interpretation of paint layer structures.

Series Editor: Ashok Roy

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First published in Great Britain in 1998 by National Gallery Publications Limited 5/6 Pall Mall East, London SW1Y 5BA

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ISBN 1 85709 220 1
ISSN 0140 7430
525270
Edited by Diana Davies and Jan Green