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Museum environment issues include temperature, humidity, light, atmospheric pollutants, and dust, which are typically controlled in buildings that contain collections of cultural and scientific significance. These environmental factors are all 'agents of deterioration' that cause damage to objects, as they play a role in deterioration pathways such as oxidation, hydrolysis, cross-linking and chain scission.[ citation needed ]
Conservators, collection managers and facility managers often work together to control the environments in which cultural heritage is stored, transported, and displayed. As the conservation-restoration profession has developed, various environmental recommendations or guidelines have emerged. The temperature and relative humidity range considered acceptable in any one cultural organisation may vary according to the type of building, the presence and type of air conditioning systems, and the types of collection material present. Many collecting organisations will also expect these conditions to be maintained during transport and when collection objects are on loan to other organisations (as part of a loan agreement).[ citation needed ]
Published environmental guidelines for museums tend to minimise both extremes and fluctuations of temperature and relative humidity. Increasingly, the benefits of environmental controls for museum collections are balanced against the energy and environmental costs of maintaining relatively tight parameters. Published guidelines now also take a more holistic approach by taking local conditions into account – e.g., that it may not be possible or appropriate for a museum located in the tropics to maintain an environment more typical of temperate regions.[ citation needed ]
Maintaining and displaying the functional capability of a mechanical heritage object enables audiences to immerse themselves in the sensory experience of the display, which imparts information about scientific and technological advances and allows people to make personal connections with the machines. [1] Operating heritage machinery also helps to keep physical components in good condition, and provides opportunities for preserving and passing on the customs and knowledge held by communities of practice who work with heritage machines. Much of this is tacit and embodied knowledge that, like riding a bicycle, has to be learnt through physical experience and practice.
Heritage machines mostly run on fossil fuels, though, which means that they rely on environmentally damaging extraction processes, emit greenhouse gases (and other pollutants), and usually leak lubricating oils. This raises the ethical question of whether operating these machines is important enough to justify their environmental impacts, and the practical question of whether the fossil fuels and lubricants they require will continue to be available/affordable for the heritage sector as the extraction, refining and distribution of these materials is reduced and/or eliminated.
Through the development of sustainability policies, heritage machinery collections can employ strategies to ensure that these cultural heritage objects continue to get exposure for generations to come.
While the emissions from heritage machines are unavoidable, carbon offsetting is a strategy that counteracts the environmental impact of running the machine as a functional display. Such offsetting strategies include:
In situations where it is socially, economically and ethically viable to reduce or negate emissions, the following strategies may apply:
During the first half of the twentieth century, many organisations and individuals noted parallels between temperature, relative humidity (RH) and the condition of objects in museum collections. Gradually, relative humidity levels between 50% and 60% became preferred, for example after observing that paintings and other collection items from Britain's National Gallery showed no further damage while stored in environmentally stable caves (58% RH) during World War II but began to crack and flake when returned to the National Gallery in London, which did not have air conditioning until 1949. Hence, when air conditioning was introduced, 58% RH was chosen as the target value. A survey conducted by Harold Plenderleith in 1960 found that most museums aimed for or experienced RH values between 50 and 60%. [10]
The Arrhenius equation, first published in 1889, has also been influential in the development of museum environmental recommendations. Broadly, the equation shows that for every 10 °C increase in temperature, the rate of chemical reactions will double. [11]
Garry Thomson's 1978 publication The Museum Environment [12] was a major influence in the development of environmental guidelines for cultural organisations and the field of preventive conservation. Though critical analysis shows that Thompson did not intend for his recommended parameters for temperature and relative humidity to become 'rules', nevertheless over the subsequent decade 50% ±5 RH and 21 °C / 70 °F ±2 became the default and preferred parameters for the international community. They became a particularly convenient standard for loan agreements. [10] [13]
Research in the 1990s and 2000s lead towards more nuanced environmental recommendations for different classes of objects and materials, based on their sensitivities. There was greater consideration of both the chemical and mechanical effects of temperature and RH.
In 1993 the Image Permanence Institute released The IPI Storage Guide for Acetate Film, written by James Reilly. Based on accelerated ageing tests, this resource showed how lowering the temperature and RH could prolong the useful life of cellulose acetate film. [14] [15] [16]
In the mid-1990s, researchers at the Conservation Analytical Lab of the Smithsonian Institution conducted research to characterise the response of wood, canvas paintings, acrylic paints, photographic emulsions and paper to fluctuations in RH, leading to more specific recommendations for allowable RH fluctuations. For example, their research found that oil and acrylic paints were susceptible to cold temperatures but little affected by RH. However, other elements in 'layered' objects such as paintings may be vulnerable to RH change, such as gesso ground layers underneath the paint, or wooden or canvas substrates. This research also drew attention to the energy costs of tight environmental controls. [17] [18] [19] [20] [21] [22]
Researchers at the Canadian Conservation Institute (CCI) also developed more nuanced guidelines for temperature and RH, categorising materials as low, medium or highly sensitive to specified parameters and specifying critical levels beyond which chemical, biological or physical change would occur. For example, at 50% RH and 20 °C a chemically stable format like black and white photographic negatives on glass is expected to have a useful life of about 300 years, compared to 1500 years at 10% RH and 20 °C. In comparison, chemically unstable materials like magnetic media formats (audio and video cassettes) are expected to have between 10 and 50 years at 50% and 10% RH respectively. [23] A moderately sensitive material might last 150 years in a warm room (25 °C) but 6,000 years at 0 °C. Waxy materials soften above 30°C (an issue for wax-lined paintings); many plastics distort above 60 °C (PET, acrylic, Nylon, ABS). Conversely, below 5 °C many paint materials enter a glassy phase that makes them more susceptible to physical damage. [24]
In 2015 the Bizot Group, also known as the International Group of Organizers of Large-Scale Exhibitions, released the Bizot Green Protocol, shifting museum environment recommendations towards mutual understandings between borrowers and lenders and factoring in more specific requirements of different categories of objects. The Green Protocol also recognised the environmental 'history' of collection objects, in that they may have experienced very different environmental conditions before they became part of a museum collection. In general, the Green Protocol called for wider parameters than those taken from Thomson's work, suggesting a range of 40-60% relative humidity and a stable temperature in the range 16-25 °C with fluctuations of no more than ±10% RH per 24 hours.g. [25] [26] [27]
In 2014 the International Council of Museums Conservation Committee (ICOM-CC) and the International Institute for Conservation (IIC) released a joint statement calling for sustainability and climate change to be integral considerations within museum environmental guidelines, while acknowledging the complexity of the science and relationships involved. The declaration called for transparency in loan agreements, in terms of what environmental controls are achievable and reasonable, especially when most museums worldwide do not have mechanical climate control systems. [28] [29]
In 2018, the Australian Institute for the Conservation of Cultural Materials ratified new environmental guidelines for cultural collections and endorsed the Heritage Collections Council (HCC) Guidelines for Environmental Control in Cultural Institutions published in 2002. The AICCM guidelines endorsed the calls of ICOM-CC and IIC for temperature and relative humidity guidelines to be achievable for the local climate, seek to reduce environmental impact and to prioritise passive control solutions and low-energy technology wherever possible. [30]
The climate specifications of the Applications Handbook of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) provide a range of settings for museums, galleries, archives, and libraries based on the sensitivity of the collections and the architectural setting, which also include a description of the commensurate risks and benefits of each setting. As it was regarded that a single standard would not be a suitable option for all collections, and considering the challenge and high cost of maintaining stringent environmental control, five classes of control were created, namely: Class AA, Class A, Class B, Class C, and Class D. Temperature and relative humidity set points or annual average and allowable short fluctuations for each class are as follows: [31] [32] [33]
The Environmental Guidelines Working Group of the American Institute for Conservation of Historic & Artistic Works (AIC) developed the Interim Environmental Guidelines following the roundtable discussions in 2010 held in Boston and Milwaukee, where conservation professionals and representatives from the cultural heritage profession shared about their practices and experiences related to collections climatology and discussed how the environmental parameters can adapt to challenges in the global economy and stewardship of natural resources. The interim guidelines recommend a set point in the range of 45-55% RH with an allowable fluctuation of +/- 5% and 15-25oC (59-77oF) temperature. [27] [32]
The conservation and restoration of cultural property focuses on protection and care of cultural property, including artworks, architecture, archaeology, and museum collections. Conservation activities include preventive conservation, examination, documentation, research, treatment, and education. This field is closely allied with conservation science, curators and registrars.
A museum is distinguished by a collection of often unique objects that forms the core of its activities for exhibitions, education, research, etc. This differentiates it from an archive or library, where the contents may be more paper-based, replaceable and less exhibition oriented, or a private collection of art formed by an individual, family or institution that may grant no public access. A museum normally has a collecting policy for new acquisitions, so only objects in certain categories and of a certain quality are accepted into the collection. The process by which an object is formally included in the collection is called accessioning and each object is given a unique accession number.
In conservation, library and archival science, preservation is a set of preventive conservation activities aimed at prolonging the life of a record, book, or object while making as few changes as possible. Preservation activities vary widely and may include monitoring the condition of items, maintaining the temperature and humidity in collection storage areas, writing a plan in case of emergencies, digitizing items, writing relevant metadata, and increasing accessibility. Preservation, in this definition, is practiced in a library or an archive by a conservator, librarian, archivist, or other professional when they perceive a collection or record is in need of maintenance.
With respect to cultural property, conservation science is the interdisciplinary study of the conservation of art, architecture, technical art history and other cultural works through the use of scientific inquiry. General areas of research include the technology and structure of artistic and historic works. In other words, the materials and techniques from which cultural, artistic and historic objects are made. There are three broad categories of conservation science with respect to cultural heritage: understanding the materials and techniques used by artists, study of the causes of deterioration, and improving techniques and materials for examination and treatment. Conservation science includes aspects of materials science, chemistry, physics, biology, and engineering, as well as art history and anthropology. Institutions such as the Getty Conservation Institute specialize in publishing and disseminating information relating to both tools used for and outcomes of conservation science research, as well as recent discoveries in the field.
A conservator-restorer is a professional responsible for the preservation of artistic and cultural artifacts, also known as cultural heritage. Conservators possess the expertise to preserve cultural heritage in a way that retains the integrity of the object, building or site, including its historical significance, context and aesthetic or visual aspects. This kind of preservation is done by analyzing and assessing the condition of cultural property, understanding processes and evidence of deterioration, planning collections care or site management strategies that prevent damage, carrying out conservation treatments, and conducting research. A conservator's job is to ensure that the objects in a museum's collection are kept in the best possible condition, as well as to serve the museum's mission to bring art before the public.
Conservation and restoration of metals is the activity devoted to the protection and preservation of historical and archaeological objects made partly or entirely of metal. In it are included all activities aimed at preventing or slowing deterioration of items, as well as improving accessibility and readability of the objects of cultural heritage. Despite the fact that metals are generally considered as relatively permanent and stable materials, in contact with the environment they deteriorate gradually, some faster and some much slower. This applies especially to archaeological finds.
Conservation and restoration of movable cultural property is a term used to denote the conservation of movable cultural property items in libraries, archives, museums and private collections. Conservation encompasses all the actions taken toward the long-term preservation of cultural heritage. Activities include examination, documentation, treatment, and preventive care, which is supported by research and education. Object conservation is specifically the actions taken to preserve and restore cultural objects. The objects span a wide range of materials from a variety of cultures, time periods, and functions. Object conservation can be applied to both art objects and artifacts. Conservation practice aims to prevent damage from occurring, a process known as 'preventive conservation'. The purpose of preventive conservation is to maintain, and where possible enhance, the condition of an object, as well as managing deterioration risks, such as handling and environmental conditions. Historically, object conservation was focused on the category of fine arts but now many different types of objects are conserved. Each type of object material, typically denoted by organic or inorganic then the specific medium, requires a specialized professional conservator and often requires collaborative work between museum staff, scientists, and conservators.
Collection maintenance is an area of collections management that consists of the day-to-day hands on care of collections and cultural heritage. The primary goal of collections maintenance or preventive conservation is to prevent further decay of cultural heritage by ensuring proper storage and upkeep including performing regular housekeeping of the spaces and objects and monitoring and controlling storage and gallery environments. Collections maintenance is part of the risk management field of collections management. The professionals most involved with collections maintenance include collection managers, registrars, and archivists, depending on the size and scope of the institution. Collections maintenance takes place in two primary areas of the museum: storage areas and display areas.
Collections management involves the development, storage, and preservation of cultural property, as well as objects of contemporary culture in museums, libraries, archives and private collections. The primary goal of collections management is to meet the needs of the individual collector or collecting institution's mission statement, while also ensuring the long-term safety and sustainability of the cultural objects within the collector's care. Collections management, which consists primarily of the administrative responsibilities associated with collection development, is closely related to collections care, which is the physical preservation of cultural heritage. The professionals most influenced by collections management include collection managers, registrars, and archivists.
An Objects conservator is a professional, working in a museum setting or private practice, that specializes in the conservation of three-dimensional works. They undergo specialized education, training, and experience that allows them to formulate and implement preventive strategies and invasive treatment protocols to preserve cultural property for the future. Objects conservators typically specialize in one type of material or class of cultural property, including metals, archaeological artifacts, ethnographic artifacts, glass, and ceramic art. Objects conservation presents many challenges due to their three-dimensional form and composite nature.
Disaster preparedness in museums, galleries, libraries, archives and private collections, involves any actions taken to plan for, prevent, respond or recover from natural disasters and other events that can cause damage or loss to cultural property. 'Disasters' in this context may include large-scale natural events such as earthquakes, flooding or bushfire, as well as human-caused events such as theft and vandalism. Increasingly, anthropogenic climate change is a factor in cultural heritage disaster planning, due to rising sea levels, changes in rainfall patterns, warming average temperatures, and more frequent extreme weather events.
Conservation and restoration of objects made from plastics is work dedicated to the conservation of objects of historical and personal value made from plastics. When applied to cultural heritage, this activity is generally undertaken by a conservator-restorer.
A photograph conservator is a professional who examines, documents, researches, and treats photographs, including documenting the structure and condition of art works through written and photographic records, monitoring conditions of works in storage and exhibition and transit environments. This person also performs all aspects of the treatment of photographs and related artworks with adherence to the professional Code of Ethics.
The conservation and restoration of Tibetan thangkas is the physical preservation of the traditional religious Tibetan painting form known as a thangka. When applied to thangkas of significant cultural heritage, this activity is generally undertaken by a conservator-restorer.
The cultural property storage typically falls to the responsibility of cultural heritage institutions, or individuals. The proper storage of these objects can help to ensure a longer lifespan for the object with minimal damage or degradation. With so many different types of artifacts, materials, and combinations of materials, keepers of these artifacts often have considerable knowledge of the best practices in storing these objects to preserve their original state.
Conservation-restoration of bone, horn, and antler objects involves the processes by which the deterioration of objects either containing or made from bone, horn, and antler is contained and prevented. Their use has been documented throughout history in many societal groups as these materials are durable, plentiful, versatile, and naturally occurring/replenishing.
The conservation and restoration of paintings is carried out by professional painting conservators. Paintings cover a wide range of various mediums, materials, and their supports. Painting types include fine art to decorative and functional objects spanning from acrylics, frescoes, and oil paint on various surfaces, egg tempera on panels and canvas, lacquer painting, water color and more. Knowing the materials of any given painting and its support allows for the proper restoration and conservation practices. All components of a painting will react to its environment differently, and impact the artwork as a whole. These material components along with collections care will determine the longevity of a painting. The first steps to conservation and restoration is preventive conservation followed by active restoration with the artist's intent in mind.
The conservation-restoration of panel paintings involves preventive and treatment measures taken by paintings conservators to slow deterioration, preserve, and repair damage. Panel paintings consist of a wood support, a ground, and an image layer. They are typically constructed of two or more panels joined together by crossbeam braces which can separate due to age and material instability caused by fluctuations in relative humidity and temperature. These factors compromise structural integrity and can lead to warping and paint flaking. Because wood is particularly susceptible to pest damage, an IPM plan and regulation of the conditions in storage and display are essential. Past treatments that have fallen out of favor because they can cause permanent damage include transfer of the painting onto a new support, planing, and heavy cradling. Today's conservators often have to remediate damage from previous restoration efforts. Modern conservation-restoration techniques favor minimal intervention that accommodates wood's natural tendency to react to environmental changes. Treatments may include applying flexible battens to minimize deformation or simply leaving distortions alone, instead focusing on preventive care to preserve the artwork in its original state.
The conservation and restoration of wooden artifacts refers to the preservation of art and artifacts made of wood. Conservation and restoration in regards to cultural heritage is completed by a conservator-restorer.
The 'ten agents of deterioration' are a conceptual framework developed by the Canadian Conservation Institute (CCI) used to categorise the major causes of change, loss or damage to cultural heritage objects. Also referred to as the 'agents of change', the framework was first developed in the late 1980s and early 1990s. The defined agents reflect and systematise the main chemical and physical deterioration pathways to which most physical material is subject. They are a major influence on the applied practice of conservation, restoration, and collection management, finding particular use in risk management for cultural heritage collections.
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