What Is the Role of Science in Conservation?
The identification of an artifact’s component materials is a key step in developing preventive conservation measures that reduce damage to the object by controlling its exposure to specific environmental factors—such as light, humidity, or atmospheric pollutants—to which it may be vulnerable. The surroundings of an artwork, which include exhibit cases as well as storage and transportation containers, can help protect it or can be a source of harmful volatile components. Conservation scientists work with conservators, exhibition designers, architects, and those responsible for the safe handling and transportation of the art collections to assess the suitability of materials used in the museum environment in order to mitigate any negative impact on the collection.
To determine the appropriate course of treatment for an object that has suffered damage, conservators often consult scientists to learn which materials may be original to the artifact; which may be results of degradation processes; and which may be associated with previous restoration treatments. Technical studies may be undertaken to establish the intended appearance and/or function of an artifact to inform discussions about treatment goals between conservators and curators. Conservation science, as a discipline, is also concerned with developing and testing the safety and efficacy of new materials and treatment strategies to help expand the range of options available to conservators.
The scientific study of artifacts plays an important role in the museum’s ongoing research of its existing collections and potential acquisitions. The authenticity of an object—its attribution to a particular time, place, and maker—can be confirmed or questioned by comparing its component materials and construction methods to information gained from artifacts of known origin. In addition to studies of authenticity, scientists and conservators collaborate on technical studies aimed at enriching the understanding of artists’ choices of materials and techniques.
Conservation Science and Technical Art History
Recent scientific advances have given rise to a new discipline in the field of art history: technical art history. All kinds of art can be evaluated from various perspectives, combining historical context and the physicality of the piece itself. Close examination and analysis of the materials of an artifact can lead to discoveries about the method of manufacture and can provide insight into some of the decision processes of the creator.
Conservation scientists receive training both in art practices and the use of analytical techniques that help uncover some of the secrets of artworks. A better technical understanding of a work of art allows for a new dimension in interpretation and general understanding of an individual piece, a particular artist’s body of work, or even an entire artistic movement or period in history. The significance of these findings is explored through discussions with curators, art historians, and archaeologists and is shared with museum visitors through exhibition materials, catalogues, lectures, and workshops.
Using a wide range of analysis methods, conservation scientists examine artifacts; study materials used in treatments or in the museum environment; and investigate surrogate objects subjected to accelerated aging or treatment tests. Although several instruments allow scientists to characterize materials in a non-destructive and non-invasive fashion, it can be necessary and appropriate to take very small, microscopic samples. Because ethical guidelines of professional organizations in the field of conservation prioritize the use of non-destructive approaches for materials characterization, conservation scientists collaborate with other scientists and instrument manufacturers to develop and adapt new non- or minimally invasive analytical techniques.
Non-Destructive Examination Techniques
Conservation professionals follow a code of ethics that encourages use of non-destructive examination techniques whenever possible.
A major part of analysis comes from what can be seen with the naked eye under visible light. The angle of the light can be adjusted to be either “normal” or “raking.” Normal light has two light sources at 45 degrees to the surface of the work, to give even light dispersion over the surface of the object. Raking light means using a single light source at low angle to the surface of the object. Raking light helps the viewer see the surface texture and topography.
Other adjustments can be made under visible light to help examine objects, such as magnification. Microscopes or close-up photography can help distinguish details, such as pigment particles or paint layers.
Advanced Imaging Techniques
After using visible light, conservators may use other forms of radiation to gain information about the object. Light from the ultraviolet (UV) and infrared (IR) portions of the light spectrum are two types of illumination commonly used by conservators.
Ultraviolet illumination induces fluorescence in certain material that can help conservators see the condition of the object’s surface, including the presence or absence of varnishes and areas of overpaint or added material. This technique is called ultraviolet-induced visible fluorescence (UVF) because the fluorescence is visible.
Infrared reflectography (IRR) is useful because it allows the conservators to see through surface layers. Some pigments become transparent under IR-illumination, whereas others retain opacity. This technique can help distinguish between pigments as well as reveal information such as the underdrawing of a painting.
Examination Using X-rays
X-ray radiography and X-ray fluorescence spectroscopy (XRF) are two examples of examination techniques that require specialized instrumentation to interpret data. X-ray radiography is similar to IRR because it passes light rays through an object and determines material based on opacity or translucency in X-ray illumination. XRF is similar to UVF because it determines the materials in an object through the use of fluorescence. But it differs from UVF in that it can detect material in the various layers of the object, rather than just at the surface. Additionally, XRF does not detect organic materials.
At times, a conservator needs to take a sample from an object. In accordance with the American Institute for Conservation (AIC) Guidelines for Practice, conservators will sample as infrequently as possible, taking microscopic samples and documenting where these samples originated.
Samples can inform the conservator about the stratigraphy of a painting, showing the application process a painter might have used. Conservators can also refer to samples for technical analysis with instrumentation such as the Gas Chromatography-Mass Spectrometry (GC-MS) machine to determine elemental composition of a material.
For more information about examination and treatment techniques in action, read La Fée aux Fleurs: Investigation and Conservation of a 19th-Century Outdoor Cast-Iron Sculpture, presented by Jane Gillies, senior conservator of objects and sculpture, at the 2013 ICOM-CC (International Council of Museums – Committee for Conservation) Metal Working Group Conference.