Bulletin 8 (IV:2), 1966

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A Resurrected Portrait and its Case History 

by Mervyn Ruggles, Conservator
National Conservation Research Laboratory

Résumé en français

Pages  1  |  2  

An anonymous ancestral portrait was brought to the National Gallery in 1964 for artistic evaluation. The painting, part of an estate, (1) had been found hidden behind a cupboard, covered with dust, partly detached from its stretcher, badly creased, apparently abandoned and destined for the trash heap. Study by the Research Curator, Mr Willem A. Blom, indicated that this Portrait of a Lady appeared to have been painted by a Canadian or American artist circa 1840, was a good example of portraiture of that period and was worth preserving. Subsequently, after a favourable preliminary investigation carried out in the laboratory, the painting was offered to the Board of Trustees Acquisition Committee, who decided to purchase it. The Conservation Laboratory was immediately requested to undertake the urgently needed preservation treatment. The account that follows here attempts to describe the case history of this reclamation project and the gratifying disclosure that came about during the process.

As in all art conservation procedures, documentation commenced with photography of the portrait by normal light, by ultra-violet fluorescence and by infra-red film before treatment. The picture when first received was rolled up like a window blind, paint side inwards. In Fig.1, the effect by oblique illumination shows the resulting surface irregularities. The linen canvas support was desiccated and brittle, with a five-inch-wide water stain across the lower sector. Much of the turnover edges of the canvas were tattered and had broken away, the tack heads having rusted through as well. The white ground preparation had penetrated from the front in scattered regions (Fig. 2). Examination of the margins indicated that this ground coat had been applied, most likely, by the artist himself, after the canvas was mounted on the stretcher. Chemical tests on microscopic samples demonstrated that this priming has a white lead content. An extensive network of age cracks exists throughout the smooth paint layer, most noticeable in the lighter tones of the face, hands and white lace collar. In some sectors the cracks had elevated edges, and numerous areas of paint abrasion were observed in a one-inch-wide strip at the upper edge. Several scrapes produced by pressure of a blunt object both from the front and the rear were noted. In almost every case these were accompanied by paint losses. Many tears and breaks in the canvas as well as the paint losses are evident as light spots in the ultra-violet fluorescence photograph (Fig. 3). living over the paint laver was a coating of natural resin varnish resembling a dark yellow-brown veil with a dense film of accumulated grime superimposed, which converted the dark blue dress to a formless black area and completely obscured the delicate modelling of its folds. Close inspection under the binocular microscope confirmed the evidence produced by the infra-red photographs and the ultra-violet light that no restorations, cleaning or retouching had been carried out previously. The cleared areas at the right margin, on the right hand and the collar, are solvent tests which convey to the eve the degree of discolouration produced by the old varnish and the surface accretions.

The first step in the conservation treatment was to insert a gesso mixture consisting of glue-size and calcium carbonate at all damaged places to compensate for the losses, prior to covering the paint surface completely with wet-strength tissue paper employing a thin size, in order to secure the paint structure while cleaning the back of the canvas and removing irregularities. In preparation for reinforcing the deteriorated canvas, a linen liner was stretched on a temporary frame and an adhesive mixture of four parts of yellow beeswax, four parts Multiwax W445 and one part AW2 resin was brushed on to it. The adhesive was coated also over the back of the portrait. Lamination of the new linen to the back of the old canvas was accomplished under vacuum (2) on the hot table (Figs. 4 & 5), where the temperature was gradually raised to 76 degrees Centigrade, the melting point of the adhesive, which proceeded to permeate the two fabrics and the paint structure. As the temperature returned to normal all layers became unified and consolidated.

The tissue-paper facing, having served its purpose, was released from the front using mineral spirit and water. The next stage was removal of the grime and discoloured varnish, executed in two steps. The first by means of diacetone alcohol diluted with 25% water applied with an artist's soft hog-hair brush in small areas within each of the various colour passages of the painting. The dissolved resin was taken up by rolling cylindrical dental cotton pads over the surface. In the second step, acetone on cotton-tipped applicators removed any remaining resin. The paint, of good quality, with a strong oil bond, was unaffected by the solvents used. Only after the cleaning process had reached the lower left corner was the startling discovery made of the firm clear signature' J. Bradley, Pinx / 1836' (3, 4, 5) in black paint directly over the very dark maroon background to the left of the armrest of the Empire sofa. Fig. 6 shows the signature in detail. The artist's name had remained obscured and undetected in spite of the diligent visual and optical examinations already cited above.

The lined picture was mounted on a custom-made expandable stretcher secured at each corner with miniature metal capstans and stainless-steel dowels. If the canvas requires tightening in the future, the capstans can be rotated causing the mitres to expand. A composite radiograph (6) consisting of six overlaps made after the portrait had been mounted on its new stretcher is shown in Fig. 7, where the construction of the corners is revealed. (7) The edges of the canvas are attached to the stretcher edges with zinc-coated tacks.

Following a drying period of four weeks (Fig. 8), two applications of normal butyl methacrylate dissolved in xylene were sprayed on after in-painting the gesso inserts with pigment in Lucite 2044 medium to match surrounding areas, care being exercised to avoid covering any original paint. A final coating of methacrylate containing 6% white beeswax for a mat finish completed the treatment.

This signed and dated portrait by J. Bradley, (8) representing a fashionable lady of the 1836 period, (9) now becomes a worthy addition to the nation's collection (Fig. 9). In July of this year, fresh and interesting information on artist Bradley's work has been brought to light by Mrs Mary Black and Mr Stuart Feld, whose account appears in the preceding article in this Bulletin.

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