Bulletin 2 (I:2), December 1963

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From the Laboratory of the National Gallery

by Nathan Stolow,
Chief Conservation and Scientific Research Division

Pages 1 | 2 | 3 | 4 | 5

Notes

1 Répertoire des Laboratoires de Musée et Ateliers de Restauration, Centre International d'Etudes pour la Conservation et Restauration des Biens Culturels (UNESCO), Rome, 1960.

2 Among the leading museum laboratories may be mentioned those of Istituto Centrale del Restauro, Roma; Institut Royal de Patrimoine Artistique, Bruxelles; the British Museum, London; National Gallery, London; Courtauld Institute, London; Conservation Centre, Institute of Fine Arts, New York University, New York; State Laboratories for Conservation, Warsaw; Swiss National Museum, Zurich
.
3 Annual Report, National Gallery of Canada, Ottawa, 1959-60, pp. 33-35; 1960-61, pp. 33-35; 1961-62, pp. 34-35.

4 N. Stolow, "Problems in Setting up a Museum Laboratory", Application of Science in Examination of Works of Art; Seminar at Research Laboratory Museum of Fine Arts, Boston, Sept. 15-18, 1958, 1959, pp. 1-15; N. Stolow, "Conservation and Scientific Research at the National Gallery of Canada", Professional Public Service, XLII, 1963, pp. 4-7.

5 The natural resins commonly encountered are damar, mastic, copal, elemi. A soft resin varnish refers to mastic or damar originally dissolved in alcohol, thus a "spirit varnish".

6 Shell Sol, a proprietary petroleum distillate manufactured by the Shell Oil Company of Canada, boiling range 322-384 °F, specific gravity 0.786 (60 °F), Kauri-Butanol Number 37.9, composition by volume: 41% paraffins, 38% naphthalenes, 19.2% aromatics, nil olefins.

7 Corot - Le Pont de Narni, Dossier of Examination and Treatment, Conservation and Scientific Research Division, National Gallery of Canada, 1961; treatment carried out by Mr Louis Pomerantz, Chicago.

8 The first "hot table" described in literature by H. Ruhemann, Studies in Conservation, I, 1953, pp. 73-76; the modification for vacuum application reported by R. E. Straub and S. Rees Jones in Studies in Conservation, II, 1955, pp. 55-63.

9 Comprehensive discussion on the vacuum technique for relining on the hot table in Studies in Conservation, V, 1960, pp. 1-24.

10 The National Gallery of Canada hot table measures 5 feet x 8 feet, operates on 230 volts with power of approximately 4 kilowatts. The heating units are twelve rubberized pads cemented to the underside of a 3/8 " aluminum plate. The circuits are electrically controlled from thermocouples inserted under the plate. Special devices are installed to keep the plate flat during the heating and cooling cycles yet permit lateral expansion and compression. Time versus temperature records are kept for each relining process by means of recorder connected to temperature measuring circuit. Cooling is accomplished by means of a fan and housing installed under the table.

11 The LeBron* Stretcher incorporates tite-joint fasteners (patented by Knape & Vogt, Grand Rapids, Michigan) in the mitred corners. The modifications of this stretcher now used in the National Gallery of Canada use only the nut of this fastener and attached to this a 1/4" No.20 thread hanger bolt driven into the opposite wooden member of the stretcher. Stainless steel dowels 1/4 " thick are employed in the mitred corners to keep the stretcher members in 'plane' when adjustments are made. (*J. J. LeBron, 966 East 167th St., New York 59, N.Y.)

12 Acryloid is the trade name of a series of acrylic resins manufactured by Rohm & Haas Company, Philadelphia. They are described as "polymers of esters of acrylic and methacrylic acids". Acryloid B-72 bas a specific gravity of 1.18 and viscosity of 500- 1100 centipoises in 40% toluene at 30°C. It has medium flexibility in the Acryloid series of polymers, and is marked by its colour stability and low reactivity pigments.

13 According to Mr. J. Russell Harper, the Virgin and Child attributed to the Labrosse atelier, was made c. 1720-1730 for the second parish Notre-Dame church in Montreal; after the destruction of the church in 1840 it was transferred to a church on the south shore of the St Lawrence River and subsequently brought to the Musée de Chambly.

14 The cross-section technique is somewhat similar to that described by Coremans et al. See R. Lefève and R. Sneyders, Mededelingen van de Vlaamse Chemische Vereniging, XII, 1950, pp. 99-101; P. Coremans and J. Thissen, "L'Introduction des lames minces dans l'examen des peintures", Bulletin de l'Institut Royal du Patrimoine Artistique, Il, 1959, pp. 41-46. The thin section technique employed is based on plexiglas embedding at 60°C. The technique used at the National Gallery incorporates the use of polyesters (Ward's Bioplastic, supplied by Ward's Natural Science Establishments, Rochester 9, N.Y.) together with catalyst and accelerator, hardened at 50°C for eight hours in an atmosphere of nitrogen. After sectioning and polishing one side, the cross-section was cemented face down using the same polyester composition, followed by hardening as before in an atmosphere of nitrogen (this assured a hard, and non-sticky bond between polyester and glass slide and permitted the section to be thinned down to 50 or less with no tendency for the thin section to lift away).

15 The ultra-violet fluorescence photomicrography is carried out by means of a twin-lamp fluorescence microscope equipment manufactured by Leitz and used in conjunction with an Ortholux research binocular microscope. The UV lamps are Philips CS150W mercury vapour. The UV fluorescence could be photographed by either reflected or transmitted light, after having filtered all of the visible light from the lamp source.

16 Dimethylfofmamide, (CH3)2 NCHO, boiling point 152.8 °C, known to act as a swelling agent and solvent for drying oil films, e.g. those containing linseed oil medium.

17 Labrosse - Virgin and Child, Dossier of Examination and Treatment, E 571., Conservation and Scientific Research Division, National Gallery of Canada, 1962; treatment carried out by Mr Bernard Hamelin.

18 Rhoplex is the trade name of a proprietary acrylic emulsion manufactured by Rohm & Haas Company, Philadelphia. The one used in Rhoplex AC-33 described as "an aqueous acrylic non-ionic emulsion with solids content of 46-47%, pH of 9.0 - 9.5."

19. "Commissioned through Count Carl Gustaf Tessin from the artist, as an over-door for the Royal Palace in Stockholm." Héritage de France: French Painting 1610 - 1760, 1961-62, No. 2, p. 28, reprod. in cat., Pl. 2; P. de Nolhac, Boucher, Premier Peintre du Roi, Paris, 1925, p. 80; H. Macfall, Boucher, The Man, His Time, His Art, and His Significance, London, 1908, p. 46, ref. to engraving by Duflos.

20 The only available engraving of the Toilet of Venus, thus far, is presumably in reference to Duflos by Mac fall, loc. cit. A photograph of such an engraving from Le Bibliothèque National, Paris. (Inventaire du fonds francais. BibI. nat. cab. des Est. Paris. XVIIe siècle, tome 8, p. 71) is oval in shape and has a somewhat different arrangement of putti and handmaiden.

21 Boucher - Toilet of Venus, Dossier of Examination and Treatment, E575, Conservation and Scientific Research Division, National Gallery of Canada, 1962; treatment carried out by Mr C. M. Ruggles, cross sections prepared by Mr J. M. Grant.

22 Ibid., Special examination by Mr Sheldon Keck, New York, regarding certain aspects of condition.

23 The pressure encountered in the vacuum process may be in the vicinity of 7 to 10 lbs per sq. inch which could cause, under conditions of heating (vicinity of 60-70 °C), plastic deformation of paint with resulting 'printing' through of the weave of the canvas. To minimize this condition it was found necessary to cushion the aluminum top of the hot table with wide sheets of blotting paper.

24 Shell Sol 715, a proprietary petroleum distillate manufactured by the Shell Oil Company of Canada, boiling range 352-390°F, specific gravity 0.758 (60°F) Kauri-Butanol Number 27.5. This solvent is slightly less 'aromatic' than Shell Sol, and has a higher, but narrower, boiling range.

25 Investigation of Mould Material, Sao Paulo Exhibition, 1960, Dossier E 544, Conservation and Scientific Research Division, National Gallery of Canada, 1960; examination by Mrs M. L. E. Florian.

26 M. L. E. Florian, "Application of Fungicides to Paint Surfaces: Colour and Biological Studies". Unpublished report, National Gallery of Canada, 1961-62.

27 N. Stolow, "Some Studies on the Protection of Works of Art During Travel", Recent Advances in Conservation: Contributions to the IIC Rome Conference, 1961, 1963, pp. 9-12.

28 "Une tête surgit de l'océan: est-elle normande ou viking", La Presse, Montreal, 13 August 1960. "Cette tête a été trouvée, au cours de l'été 1958, par un pêcheur de maquereaux dans de cent pieds d'eau au large de Percé, près de l'Île Bonaventure On est presque assuré qu'elle remonte qu'elle provient d'un drakkar viking qui aurait pu côtoyer dans les parages."

29 Anon. Head of Woman, Dossier of Examination, E541, Conservation and Scientific Research Division, National Gallery of Canada, 1960; examinations carried out by N. Stolow, M. L. E. Florian, H. A. Crum (National Museum of Canada), and J. D. Hale (Forest Products Laboratory, Ottawa) .

30 N. Stolow, I. Oil Colour Chemists Association XL, 1957, Part I, pp. 377-402, Part Il, pp. 488-499.

31 N. Stolow, "Application of Science to Cleaning Methods: Solvent Action Studies on Pigmented and Unpigmented Linseed Oil Films", Recent Advances in Conservation: Contributions to the IIC Rome Conference, 1961, 1961, pp. 84-88.

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