1. Before conservation

Transcription

1 Adoration of the Magi Circle of Frans Francken II, Casper van der Hoecke II (?)? 1640 Oil on oakwood cm EKM VM 932 Conservator: Alar Nurkse, conservator of painting, 1. Before conservation The painting was given to the Art Museum of Estonia in 1986 by Mrs. Ilse Karring. The panel of the painting in a newer profile frame consists of oak boards, of which the upper one had come unglued. In the damaged areas of the painting with craquelure and loose and layered paint, silk-paper stickers had been placed for protection by an unknown restorer-conservator. (Fig. 1., 2.) 2. Before conservation 3. Detail of the Antwerp Guild of Saint Luke

2 I. Studies: inspection using different kinds of light, study of cross-sections and the structure of the paint layer under a microscope with magnification of up to 200 ; study of the ground; UV radiation; IR reflectography; X-radiograph study. 4. Gluing the boards together 5. Detail during the work in progress Inspection under different light and with a microscope: The panel of the painting was made of four horizontal oak boards. On the back side in the centre, there is a quality sign of the Antwerp Guild of Saint Luke, which is partially visible. (Fig. 3.) The ground is thin, white and uniformly dense without major discernible granulation. A greyishbrown priming has been applied on the ground. The painting was carried out with different brushes and paints visually based on oil binder. A slow-drying binder was used, which enabled the artist to work with fine, melting hues, and build up and shape details of the composition. Different paintings, with both a semi-transparent and an opaque paste, with a primarily fine brushwork, for instance, in the light areas of the images (Fig. 5, 11, 12, 13). The whole surface of the painting had different types of damage: losses, cracks, layers, blisters, abrasions and so on. We could distinguish over-paintings, which were the most extensive on the connection areas between the boards. Cross-sections of the paint: the glue and chalk ground is a uniform white mass. The greyish-brown primuersel-imprimatura contains predominantly white, with a single distinct area of black and red, particles in varying size. The painting consists of up to two paint layers (see Fig. 14). The varnish applied by the artist is a yellowish-brownish layer visible in a few cross-sections. Paint layers that were added later and the topmost varnish layer are easily distinguishable. Black particles in the varnish make the substance seem coloured and look older, like gallery varnish (Fig. 12, 13, 16, 17). 11. Detail in regular light after partial cleaning Ground analysis (Report No16. by , J. Kaup): carbonate composition chalk of the main mass of the ground with animal glue. UV examination: luminescence of a thick, relatively uneven layer of varnish, with over-paintings; traces of test cleaning and dark uncleaned check areas are visible. (Fig. 6, 7) IRR examination: Infra-red reflectography did not show clear lines of an under-drawing, but there were traces of the artist s search, e.g. improvements and corrections of the image of the king Melchior near the Christ child. The horizontal lines of brushwork are the traces of the primuersel-imprimatura colour coat. IRR examinations were carried out both before and after the painting was cleaned, which improved the quality of distinction (Fig. 8, 9) Detail after the conservation and before cleaning X- radiograph images were taken with Siemens equipment (105 cm, 57 KV, 8.0 mas). The digital image of the two-dimensional plane on the screen shows a trace of soft radiation being absorbed or passing through it in a three-dimensional panel. The X-radiograph of the oak boards shows fine, uniformly sharp lines of concentric rings. The connections between the boards and the support patches horizontally glued on the cracks are also visible. The panel has a thin, relatively even layer of ground coat. Older and more recent losses show clear outlines and appear in different tonalities. The interplay of the colour facture and traces of brushwork can be interpreted as the striving for an accurate representation of the

3 material. The contrasting tonalities evident on examination indicate the use of dyes containing metal compounds with different atomic weights. Painting in strings has left traces of different tonalities on the X-ray, indicating areas where the artist sought exactness with fine brushwork and paints mixed with white (Fig. 15). II. Conservation treatments: 6. UV fragment with partial cleaning 7. UV fragment with tests of cleaning 8. Detail after partial cleaning in IRR ex- 9. Detail after cleaning in IRR examination 10. Test cleaning 1. Conservation of the painting Where it was possible in damaged areas, old silk-paper stickers were removed with warm water and a cotton swab. Where it was not possible, the craquelure and blistered areas were fixed locally with approx. 7% sturgeon glue. After being checked and after repeated conservation, the stickers were removed and the surface cleaned, leaving some check areas. The losses were filled with a mixture of approx. 5% sturgeon glue and chalk. 2. Conservation of the panel A support system was built to glue the loose warped boards back together. The sides of the boards were cleaned mechanically with a scalpel. The right side of the connecting area, which had insect damage, was strengthened with 4% Paraloid B72 in acetone, and dried. Then, approx. 12% rabbit-skin glue was applied to the connection areas; they were joined with maximum evenness on the front side, and pressed together with moderate pressure. (Fig. 4) 3. To thin the varnish and to remove over-paintings, we experimented with solvent mixes of different components and with the Pettenkofer method, using ethanol (Schmitt 1990: 81 84). (Fig. 10) 1. Pettenkofer method with ethanol: 1-4 minutes exposure time 2. Ethanol + turpentine: 1:1 3. Ethanol + turpentine: 1:4 4. Ethanol + turpentine: 1:3 5. Ethanol + turpentine: 1:2 The most suitable solution for thinning the varnish was the Pettenkofer method, with two minutes of exposure time. A good result was also achieved with a hard cotton swab dipped in a mixture of ethanol and turpentine at a ratio of 1:2. Thinning the thick varnish layer was a time-consuming process. The surface of the painting had more than two layers of varnish, of which the most recent one could be easily removed with a mixture of ethanol and turpentine. The second layer underneath that one had been coloured and decorated with a craquelure painting, carried out with different brushes (Fig. 13, 17). Between the first (probably original) and second layer of varnish, there were over-paintings, most extensive in the sky area and on the connections between the boards (Fig. 18, 19). The over-paintings were removed with micro-scalpels after the completion of the Pettenkofer process. 4. Retouching of losses After the varnish had been thinned and over-paintings removed, the surrounding surface around the conservation ground was about one millimetre higher. These areas of ground were thinned and then covered with a solution of turpentine and dammar varnish in a ratio of 1:1. The retouching was carried out with oil paints. After the retouching had dried, varnish was sprayed onto the painting (dammar and turpentine 1:1; spray gun: KREMLIN HTI; compressed air: 0.8 atm).

4 Cross-section VM932-1: 1 ground 2 ground coat (appears to be animal glue on visual estimation) 3 primuersel-imprimatura 4, 5 original painting 6 varnish 7 over-painting 8 recent coloured varnish 15. Detail from X-radiograph with traces of damages, losses and brush-strokes Fragments with uneven varnish and craquelure painting in process of cleaning Photomicrograph of a detail of sky in process of cleaning with removal of over-paintings with crackle

5 5. It was decided to replace the old frame, which was of unsuitable construction and aesthetically dubious, with a new optimal climate-controlled framebox: a modern Salvadori wooden frame was used (94 mm , painted black with acrylic paint); the front side was fitted with museum glass; the back side was fitted with a polycarbonate protective panel with screws. 20. After conservation Conservation/restoration, some of the studies, cross-sections, framing and photographing were carried out by Alar Nurkse. I would like to thank Tiit Villemsoo, Sirje Säär, Jüri Kaup and Signe Vahur. Sources: The Structural Conservation of Panel Paintings. Eds. Kathleen Dardes and Andrea Rothe; The Getty Conservation Institute, Los Angeles, 1998; Cleaning, Retouching and Coatings. Technology and Practice for Easel Paintings... Eds. J. S. Mills and P. Smith; Preprints of the Contributions to the Brussels Congress, 3 7 Sept. 1990; P. Achternkamp, Der Rückseitenschutz von Gemälden: Historische und zeitgenössische Praxis; Zeitschrift für Kunsttechnologie und Konservierung Jahrgang 5/1991, Heft 1 Materials used: stugeon glue, rabbit-skin glue, Paraloid B72, acetone, chalk, Turpentine AP Chemicals, Dammar Varnish, Nevskaja Palitra St Petersburg, Paints: Rembrandt, Talens, Netherlands; Master Class, Saint Petersburg, Russia, ethanol, Makrolon Multy, True Vue AR Reflection-Free Glass