From the Laboratory of the National
by Nathan Stolow,
Chief Conservation and Scientific Research
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| 3 | 4
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
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 -
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.
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."
Anon. Head of Woman, Dossier of Examination, E541,
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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