Conservation encompasses a range of endeavours that seek to preserve and restore cultural material, such as paintings, drawings and prints, sculpture, and decorative arts, all of which deteriorate over time from the effects of environment, the inherent instability of the artistic materials, and misguided human interventions. A fundamental objective of conservation is to provide works of art with suitable physical and environmental conditions for their safekeeping. Modern-day museums with proper display and storage, controlled light levels that eliminate damaging ultraviolet radiation, and stable levels of temperature and relative humidity exemplify this concept of preservation. Moreover, conservation concerns itself with the physical condition and aesthetic appearance of the object, which may necessitate treatments to repair and alleviate a variety of condition problems. Conservation treatments are informed and guided by the careful visual examination and documentation of the work of art and take into consideration the short- and long-term effects of any material or procedure used. Critical in this process is a thorough understanding of artistic materials and how they age. Working collaboratively with conservation scientists, modern-day conservators employ a variety of sophisticated analytical tools in their work. During the study and conservation of a painting, much is learned about the materials and techniques used by the artist, which adds to a growing body of knowledge about the artistic process.
Works of art are composed of a variety of materials that react differently to the effects of light, temperature, and relative humidity. A traditional oil painting on canvas is composed of a linen fabric that is stretched over an adjustable wood frame. The linen is sealed and primed with an oil- or water-based ground layer onto which the artist executes the painting. The paint layers, which consist of pigments bound in a drying oil, such as linseed oil, ultimately harden to an inflexible film on the canvas surface. Finally, a varnish layer is typically applied to saturate and protect the paint layers. The differential expansion and contraction of these materials in response to fluctuating humidity and temperature creates stresses within the structure of the painting, causing cracks to form in the paint layers. Over time, further weakening of the paint and canvas support can lead to instability and paint loss. Nonetheless, when quality materials and sound artistic practice are employed, and environmental conditions are favourable, paintings can remain remarkably stable over long periods of time. By contrast, the use of poor materials or shoddy artistic technique can initiate degradation as soon as the object leaves the artist’s studio. Earth pigments are generally stable, but those composed of dye colours may not be and can fade irreversibly on exposure to light. Accidents can result in tears to the canvas or splits in wood panel supports. Less perceptible changes occur within the paint film itself, as volatile components leach out of the surface either from inherent deterioration processes or from the use of strong cleaning solvents during cleaning procedures. The slow deterioration of paint layers inevitably results in a dull paint surface no longer having the intensity of colour it originally possessed. Many paintings have been irreparably altered by owners and dealers who intentionally disassembled paintings for profit or repurposed them to satisfy changes in taste. The portrait of a man in the manner of Tintoretto (Cat. #) is an example of a painting where the original composition has been modified, having been cut down from a larger composition and subsequently relined to fit a new presentation format. The chemical and physical changes that occur to a painting over time can have a profound effect on its appearance and our comprehension of what the artist intended.
The terms conservation and restoration are often used interchangeably to describe the duties of the modern-day conservator, and while the two activities are closely interrelated, each has distinct objectives. Conservation is directed towards preservation of the work of art, typically involving stabilization methods to slow down deterioration and prevent further damage. For example, flaking paint, which might be lost if left unattended, is stabilized with an appropriate adhesive and then carefully reattached to the surface of the painting. The goal of conservation is to preserve as much of the original as possible. Even passive treatments, such as proper reframing and attachment of a protective backing board to the reverse of the painting, go a long way towards its conservation. Restoration efforts, on the other hand, focus on the appearance of a painting and strive to repair damages and alterations that have occurred to the work. The mending of tears in the canvas or the removal of an old, yellowed dammar varnish from the paint surface are examples of restoration procedures. Visually disruptive losses in the image are compensated for by inpainting, thereby “restoring” the composition and overall visual effect. While the term restoration implies that a work of art can be brought back to its original state, this is in fact not possible. Once physical and chemical changes (such as cracking of the paint layers and fading of pigments) have occurred, they are permanent and cannot be reversed. Another challenging problem for the conservator is the question of the artist’s intent. What did the painter actually intend the finished work to look like? Was the painting to be varnished or left unvarnished? The complexity of conserving and restoring paintings was considered by Gerry Hedley, who remarked that “we cannot return to the original intention and so must construct a new relationship between the artist’s original intention, the present work, and the passage of time.”[i] Working in collaboration with museum curators, art historians, and conservation scientists, it is possible for the conservator to interpret historical evidence and analytical findings to perform the most judicious conservation treatment possible, both for the painting’s long-term preservation and to make it visually engaging for the viewer.
Formalized training of conservators and research into artists’ materials and techniques based on scientific principles did not become a serious endeavour until the twentieth century. Before the eighteenth century, the task of cleaning and repairing paintings invariably fell to the hands of artists. A famous example of this occurred in 1603 when Peter Paul Rubens went to Spain to deliver paintings to King Philip III as part of a diplomatic mission. While en route, heavy rainstorms damaged a number of paintings, which were thought to be ruined. Instead of relying on others to perform the restorations, Rubens took it upon himself to repaint the damages, and onlookers at the Spanish court deemed his repairs to be of exceptional quality.[ii] In the eighteenth and nineteenth centuries restorers learned their trade empirically, carrying out their practice with little understanding of the degradation processes that afflict works of art. The results of these interventions, especially cleaning procedures, were mixed at best. The range of materials recommended for cleaning paintings included water, urine, and lye; the latter two are especially harmful to oil paint layers and the delicate glazes applied by artists as finishing touches to their work. The over-cleaning of paintings necessitated the repainting of damaged areas, often carried out in an excessive manner that obscured large portions of the original composition. Throughout the nineteenth and twentieth centuries, greater awareness of the variable quality of treatments, especially the cleaning of paintings, drew critical attention to restoration practices. The most famous controversy erupted in the mid-1840s at the National Gallery, London. The removal of heavy brown layers of varnish from pictures shocked some viewers and provoked an impassioned public debate, which led to the House of Commons appointing a select committee to investigate the manner in which paintings were being treated at the institution.[iii] The discussion concerning restoration and conservation procedures has continued unabated since then, and although many issues remain unresolved, a more reflective attitude has developed within the field. Where in the past, lining and cleaning of paintings were thought of as routine and required procedures—something to be done as a matter of course—conservation treatments have, over the last half-century, become far less invasive and frequent.
Today, conservators perform wide-ranging activities that go beyond conserving and restoring works of art. In the modern museum setting it is common for conservators to undertake many investigative procedures to answer questions about condition, artistic technique, and attribution. To do this they work closely with conservation scientists and use an array of imaging techniques including infrared reflectography and X-radiography. Minute paint samples are taken and examined as cross sections under high-powered microscopes to determine the stratigraphy and composition of paint and varnish layers, and the presence of restorations and grime. Many conservation labs are also equipped with non-destructive tools such as portable X-ray fluorescence analyzers that can quickly determine the elemental makeup of works of art. In the realm of cleaning paintings, great strides have been made with the introduction of gel cleaning systems as an alternative to more aggressive solvent mixtures. The pioneering work of Richard Wolbers enables conservators to apply controlled cleaning solutions to paint surfaces, thereby greatly reducing the risk of swelling and leaching of the paint medium.[vi] The innovations introduced over the past half-century provide the conservator with an unparalleled array of approaches unthinkable at the dawn of modern conservation. Combined with a more thorough understanding of past practices, ethical and philosophical considerations, and the history of the artwork, a more measured approach is possible when treatments and technical examinations are performed.
The paintings selected for this exhibition offer the viewer not only the opportunity to examine paintings composed of a range of artistic materials and techniques but also to consider some intriguing questions about their condition and conservation. Initially, they were examined by this author to determine their suitability for in-depth investigation. Previous conservation records were reviewed, and the paintings were examined visually and under ultraviolet light. Questions regarding their state of preservation and recommendations for further analytical work were detailed in written reports that were reviewed by the collaborating authors. Some of the paintings entered the McMaster Art Museum collection relatively unscathed and are in a pristine state of preservation, while others show signs of damage and multiple restoration interventions. For example, the painting by Rodchenko (Cat. #), executed with thin, translucent applications of paint directly on its softwood panel support, has a small vertical split just to the left of the artist’s signature, but otherwise shows no signs of ever having been cleaned or restored. By contrast, Vincent van Gogh’s Untitled, Still Life: Ginger Pot and Onions (Cat. #) has undergone invasive treatments including wax lining onto a linen support, selective cleaning of the varnish, and restoration of painting losses. To complicate matters further, Van Gogh himself appears to have reused a canvas on which he had previously painted an entirely different composition. To the naked eye, however, most of these condition problems are not readily apparent because, in the past, distracting damages or changes that occurred to the paint surface were hidden by restorers. It is only through the various imaging and analytical techniques recently performed on the group of paintings in this exhibition, and described in detail in the other essays in this volume, that we can better appreciate their physical condition and what has happened to them over time.
[i] Gerry Hedley, “Long Lost Relations and New Found Relativities: Issues in the Cleaning of Paintings,” in Measured Opinions: Collected Papers on the Conservation of Paintings, ed. Caroline Villers (London: United Kingdom Institute for Conservation, 1993), 172–78.
[ii] Michael Jaffé, Rubens and Italy (Oxford: Phaidon Press, 1977), 68.
[iii] For a more detailed review of these issues, see Sheldon Keck, “Some Picture Cleaning Controversies: Past and Present,” Journal of the American Institute for Conservation 23, no. 2 (Spring 1984): 73–87; and also Report from the Select Committee on the National Gallery (London: National Gallery Archive, 1853), vi–xi.
[iv] For a comprehensive account of the history of technical studies and research at the Fogg Museum, see Francesca G. Bewer, A Laboratory for Art: Harvard’s Fogg Museum and the Emergence of Conservation in America, 1900–1950 (New Haven, CT: Yale University Press, 2010).
[v] Joyce Hill Stoner, “Changing Approaches in Art Conservation: 1925 to the Present,” Scientific Examination of Art: Modern Techniques in Conservation and Analysis (Washington, DC: The National Academies Press, 2005), 50.
[vi] For more on this seminal work, see Richard Wolbers, Cleaning Painted Surfaces: Aqueous Methods, (London: Archetype Publications Ltd., 2000).
 Gerry Hedley, “Long Lost Relations and New Found Relativities: Issues in the Cleaning of Paintings,” in Measured Opinions: Collected Papers on the Conservation of Paintings, ed. Caroline Villers (London: United Kingdom Institute for Conservation, 1993), 172–78.
 Michael Jaffé, Rubens and Italy (Oxford: Phaidon Press, 1977), 68.
 For a more detailed review of these issues, see Sheldon Keck, “Some Picture Cleaning Controversies: Past and Present,” Journal of the American Institute for Conservation 23, no. 2 (Spring 1984): 73–87; and also Report from the Select Committee on the National Gallery (London: National Gallery Archive, 1853), vi–xi.
 For a comprehensive account of the history of technical studies and research at the Fogg Museum, see Francesca G. Bewer, A Laboratory for Art: Harvard’s Fogg Museum and the Emergence of Conservation in America, 1900–1950 (New Haven, CT: Yale University Press, 2010).
 Joyce Hill Stoner, “Changing Approaches in Art Conservation: 1925 to the Present,” Scientific Examination of Art: Modern Techniques in Conservation and Analysis (Washington, DC: The National Academies Press, 2005), 50.
 For more on this seminal work, see Richard Wolbers, Cleaning Painted Surfaces: Aqueous Methods, (London: Archetype Publications Ltd., 2000).