Conservation and restoration of cultural property

Some consider the tradition of conservation of cultural heritage in Europe to have begun in 1565 with the restoration of the Sistine Chapel frescoes, but more ancient examples include the work of Cassiodorus.[7]

A temporary windowed partition along restoration work area in the cloister of the Church of St. Trophime, Arles

The care of cultural heritage has a long history, one that was primarily aimed at fixing and mending objects for their continued use and aesthetic enjoyment.[8] Until the early 20th century, artists were normally the ones called upon to repair damaged artworks. During the 19th century, however, the fields of science and art became increasingly intertwined as scientists such as Michael Faraday began to study the damaging effects of the environment to works of art. Louis Pasteur carried out scientific analysis on paint as well.[9] However, perhaps the first organized attempt to apply a theoretical framework to the conservation of cultural heritage came with the founding in the United Kingdom of the Society for the Protection of Ancient Buildings in 1877. The society was founded by William Morris and Philip Webb, both of whom were deeply influenced by the writings of John Ruskin. During the same period, a French movement with similar aims was being developed under the direction of Eugène Viollet-le-Duc, an architect and theorist, famous for his restorations of medieval buildings.

Since 1998, Harvard University wraps some of the valuable statues on its campus, such as this "Chinese stele", with waterproof covers every winter, in order to protect them from erosion caused by acid rain.[10]

Conservation of cultural heritage as a distinct field of study initially developed in Germany, where in 1888 Friedrich Rathgen became the first chemist to be employed by a Museum, the Koniglichen Museen, Berlin (Royal Museums of Berlin). He not only developed a scientific approach to the care of objects in the collections, but disseminated this approach by publishing a Handbook of Conservation in 1898.[11] The early development of conservation of cultural heritage in any area of the world is usually linked to the creation of positions for chemists within museums. In British archaeology, key research and technical experimentation in conservation was undertaken by women such as Ione Gedye both in the field and in archaeological collections, particularly those of the Institute of Archaeology, London.

In the United Kingdom, pioneering research into painting materials and conservation, ceramics, and stone conservation was conducted by Arthur Pillans Laurie, academic chemist and Principal of Heriot-Watt University from 1900. Laurie's interests were fostered by William Holman Hunt.[12] In 1924 the chemist Harold Plenderleith began to work at the British Museum with Alexander Scott in the recently created Research Laboratory, although he was actually employed by the Department of Scientific and Industrial Research in the early years. Plenderleith's appointment may be said to have given birth to the conservation profession in the UK, although there had been craftsmen in many museums and in the commercial art world for generations.[13] This department was created by the museum to address the deteriorating condition of objects in the collection, damages which were a result of their being stored in the London Underground tunnels during the First World War. The creation of this department moved the focus for the development of conservation theory and practice from Germany to Britain, and made the latter a prime force in this fledgling field. In 1956 Plenderleith wrote a significant handbook called The Conservation of Antiquities and Works of Art, which supplanted Rathgen's earlier tome and set new standards for the development of art and conservation science.

In the United States, the development of conservation of cultural heritage can be traced to the Fogg Art Museum, and Edward Waldo Forbes, its director from 1909 to 1944. He encouraged technical investigation, and was Chairman of the Advisory Committee for the first technical journal, Technical Studies in the Field of the Fine Arts, published by the Fogg from 1932 to 1942. Importantly he also brought onto the museum staff chemists. Rutherford John Gettens was the first of such in the US to be permanently employed by an art museum. He worked with George L. Stout, the founder and first editor of Technical Studies. Gettens and Stout co-authored Painting Materials: A Short Encyclopaedia in 1942, reprinted in 1966. This compendium is still cited regularly. Only a few dates and descriptions in Gettens' and Stout's book are now outdated.[14]

George T. Oliver, of Oliver Brothers Art Restoration and Art Conservation-Boston (Est. 1850 in New York City) invented the vacuum hot table for relining paintings in 1920s; he filed a patent for the table in 1937.[15] Taylor's prototype table, which he designed and constructed, is still in operation. Oliver Brothers is believed to be the first and the oldest continuously operating art restoration company in the United States.

The focus of conservation development then accelerated in Britain and America, and it was in Britain that the first International Conservation Organisations developed. The International Institute for Conservation of Historic and Artistic Works (IIC) was incorporated under British law in 1950 as "a permanent organization to co-ordinate and improve the knowledge, methods, and working standards needed to protect and preserve precious materials of all kinds."[14] The rapid growth of conservation professional organizations, publications, journals, newsletters, both internationally and in localities, has spearheaded the development of the conservation profession, both practically and theoretically. Art historians and theorists such as Cesare Brandi have also played a significant role in developing conservation science theory. In recent years ethical concerns have been at the forefront of developments in conservation. Most significantly has been the idea of preventive conservation. This concept is based in part on the pioneering work by Garry Thomson CBE, and his book Museum Environment, first published in 1978.[16] Thomson was associated with the National Gallery in London; it was here that he established a set of guidelines or environmental controls for the best conditions in which objects could be stored and displayed within the museum environment. Although his exact guidelines are no longer rigidly followed, they did inspire this field of conservation.

The Lunder Conservation Center. Conservation staff for both the Smithsonian American Art Museum and the National Portrait Gallery are visible to the public through floor-to-ceiling glass walls that allow visitors to see firsthand all the techniques that conservators use to examine, treat and preserve artworks within a functioning conservation Laboratory.

Conservators routinely use chemical and scientific analysis for the examination and treatment of cultural works. The modern conservation laboratory uses equipment such as microscopes, spectrometers, and various x-ray regime instruments to better understand objects and their components. The data thus collected helps in deciding the conservation treatments to be provided to the object.

Many cultural works are sensitive to environmental conditions such as temperature, humidity and exposure to visible light and ultraviolet radiation. These works must be protected in controlled environments where such variables are maintained within a range of damage-limiting levels. For example, watercolour paintings usually require shielding from sunlight to prevent fading of pigments.

Collections care is an important element of museum policy. It is an essential responsibility of members of the museum profession to create and maintain a protective environment for the collections in their care, whether in store, on display, or in transit. A museum should carefully monitor the condition of collections to determine when an artifact requires conservation work and the services of a qualified conservator.

Work of preventive conservation in a rock wall with prehistoric paintings at the Serra da Capivara National Park. The work consists of filling the cracks to prevent the fragmentation of the wall.

Furniture conservation – Re-glueing loose element of solid nut marriage chest (probably Italy, 19th century)

Antique conservation – Re-painting of the frame by museum employee

A teaching programme of interventive conservation was established in the UK at the Institute of Archaeology by Ione Gedye, which is still teaching interventive conservators today.[24]

A principal aim of a cultural conservator is to reduce the rate of deterioration of an object. Both non-interventive and interventive methodologies may be employed in pursuit of this goal. Interventive conservation refers to any direct interaction between the conservator and the material fabric of the object. Interventive actions are carried out for a variety of reasons, including aesthetic choices, stabilization needs for structural integrity, or cultural requirements for intangible continuity. Examples of interventive treatments include the removal of discolored varnish from a painting, the application of wax to a sculpture, and the washing and rebinding of a book. Ethical standards within the field require that the conservator fully justify interventive actions and carry out documentation before, during, and after the treatment.

One of the guiding principles of conservation of cultural heritage has traditionally been the idea of reversibility, that all interventions with the object should be fully reversible and that the object should be able to be returned to the state in which it was prior to the conservator's intervention. Although this concept remains a guiding principle of the profession, it has been widely critiqued within the conservation profession[25] and is now considered by many to be "a fuzzy concept."[26] Another important principle of conservation is that all alterations should be well documented and should be clearly distinguishable from the original object.[17]

An example of a highly publicized interventive conservation effort would be the conservation work conducted on the Sistine Chapel.

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  First archaeological search in the 19th-century layer by French archaeologist and restorer Yves Morvan
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  Painting of the 15th century cleared before restoration
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  Painting after restoration

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  Bacchus, the painting originating from the Workshop of Leonardo da Vinci, seen here before restoration.
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  Bacchus after restoration with colors closer to original and details better visible again.

Conservators and restorers use a wide variety of materials - in conservation treatments, and those used to safely transport, display and store cultural heritage items. These materials can include solvents, papers and boards, fabrics, adhesives and consolidants, plastics and foams, wood products, and many others. Stability and longevity are two important factors conservators consider when selecting materials; sustainability is becoming an increasingly important third.[33] Examples of sustainable material choices and practices include:

• Using biodegradable products or those with less environmental impact where possible;
• Using 'green solvents' instead of more toxic alternatives, or treatment strategies that use much smaller amounts of solvents - for example, semi-rigid aqueous gels, emulsions or nano materials;[34][35]
• Preparing smaller amounts of material (e.g. adhesives) to avoid waste;
• Observing recommended disposal protocols for chemicals, recyclable materials and compostable materials, particularly to avoid contamination of waterways;
• Choosing protective work wear that can be washed or cleaned and reused, rather than disposable options;
• Tracking stock quantities to avoid over-buying, especially for materials with expiration dates;
• Using durable materials for packing that may be washed and re-used, such as Tyvek or Mylar;[36][37]
• Repurposing consumables such as blotting paper, non-woven fabrics, and polyester film when they are no longer fit for their original purpose;
• Using locally produced products whenever possible, to reduce carbon footprints;
• Reusing packaging materials such as cardboard boxes, plastic wrap and wooden crates;[38]
• Using standard sizes of packaging and package designs that reduce waste;

These decisions are not always straightforward - for example, installing deionised or distilled water filters in laboratories reduces waste associated with purchasing bottled products, but increases energy consumption. Similarly, locally-made papers and boards may reduce inherent carbon miles but they may be made with pulp sourced from old growth forests.

Another dilemma is that many conservation-grade materials are chosen because they do not biodegrade. For example, when selecting a plastic with which to make storage enclosures, conservators prefer to use relatively long-lived plastics because they have better ageing properties - they are less likely to become yellow, leach plasticisers, or lose structural integrity and crumble (examples include polyethylene, polypropylene, and polyester). These plastics will also take longer to degrade in landfill.

Many conservators and cultural organisations have sought to reduce the energy costs associated with controlling indoor storage and display environments (temperature, relative humidity, air filtration, and lighting levels) as well as those associated with the transport of cultural heritage items for exhibitions and loans.

In general, lowering the temperature reduces the rate at which damaging chemical reactions occur within materials. For example, storing cellulose acetate film at 10 °C instead of 21 °C is estimated to increase its usable life by over 100 years.[39] Controlling the relative humidity of air helps to reduce hydrolysis reactions and minimises cracking, distortion and other physical changes in hygroscopic materials. Changes in temperature will also bring about changes in relative humidity. Therefore, the conservation profession has placed great importance on controlling indoor environments. Temperature and humidity can be controlled through passive means (e.g. insulation, building design) or active means (air conditioning). Active controls typically require much higher energy use. Energy use increases with specificity - e.g. in will require more energy to maintain a quantity of air to a narrow temperature range (20-22 °C) than to a broad range (18-25 °C). In the past, conservation recommendations have often called for very tight, inflexible temperature and relative humidity set points. In other cases, conservators have recommended strict environmental conditions for buildings that could not reasonably be expected to achieve them, due to the quality of build, local environmental conditions (e.g. recommending temperate conditions for a building located in the tropics) or the financial circumstances of the organisation. This has been an area of particular debate for cultural heritage organisations who lend and borrow cultural items to each other - often, the lender will specify strict environmental conditions as part of the loan agreement, which may be very expensive for the borrowing organisation to achieve, or impossible.

The energy costs associated with cold storage and digital storage are also gaining more attention. Cold storage is a very effective strategy to preserve at-risk collections such as cellulose nitrate and cellulose acetate film, which can deteriorate beyond use within decades at ambient conditions. Digital storage costs are rising for both born-digital cultural heritage (photographs, audiovisual, time-based media) and to store digital preservation and access copies of cultural heritage. Digital storage capacity is a major factor in the complexity of preserving digital heritage such as video games,[40] social media, messaging services, and email.

Other areas where energy use can be reduced within conservation and restoration include:

• Exhibition lighting - e.g. using lower-energy LED lighting systems and light sensors that switch lights on only when visitors are present;[41]
• Installation of green energy capture systems in cultural organisations, such as solar photovoltaic plates, wind energy systems, and heat pumps;[42]
• Improving the energy performance of cultural buildings by installing insulation, sealing gaps, reducing the number of windows and installing double-glazing:[42]
• Using microclimates to house small groups of climate-sensitive objects instead of seeking to control the environmental conditions of the whole building.[42]

Heritage Preservation, in partnership with the Institute of Museum and Library Services, a U.S. federal agency, produced The Heritage Health Index. The results of this work was the report A Public Trust at Risk: The Heritage Health Index Report on the State of America's Collections, which was published in December 2005 and concluded that immediate action is needed to prevent the loss of 190 million artifacts that are in need of conservation treatment. The report made four recommendations:[43]

• Institutions must give priority to providing safe conditions for the collections they hold in trust.
• Every collecting institution must develop an emergency plan to protect its collections and train staff to carry it out.
• Every institution must assign responsibility for caring for collections to members of its staff.
• Individuals at all levels of government and in the private sector must assume responsibility for providing the support that will allow these collections to survive.[4]

Conservation in Progress note, Victoria and Albert Museum (2014)

In October 2006, the Department for Culture, Media and Sport, a governmental department, authored a document: "Understanding the Future: Priorities for England's Museums".[44] This document was based on several years of consultation aimed to lay out the government's priorities for museums in the 21st century.

The document listed the following as priorities for the next decade:

1. Museums will fulfil their potential as learning resources (pp 7–10).
   • Museums will be embedded into the delivery of education in every school in the country.
   • Understanding of the effectiveness of museum education will be improved further and best practice built into education programmes.
   • The value of museums' collections as a research resource will be well understood and better links built between the academic community and museums.
2. Museums will embrace their role in fostering, exploring, celebrating and questioning the identities of diverse communities (pp 11–14).
   • The sector needs to work with partners in academia and beyond to create an intellectual framework supporting museums' capacity to tackle issues of identity.
   • The museum sector must continue to develop improved practical techniques for engaging communities of all sorts.
3. Museums' collections will be more dynamic and better used (pp 15–18).
   • Government and the sector will find new ways to encourage museums to collect actively and strategically, especially the record of contemporary society.
   • The sector will develop new collaborative approaches to sharing and developing collections and related expertise.
4. Museums' workforce will be dynamic, highly skilled and representative (pp 17–22).
   • Museums' governing bodies and workforce will be representative of the communities they serve.
   • Find more varied ways for a broader range of skills to come into museums.
   • Improve continuing professional development.
5. Museums will work more closely with each other and partners outside the sector (pp 23–26).
   • A consistent evidence base of the contribution of all kinds of museums to the full range of public service agendas will be developed.
   • There will be deeper and longer lasting partnerships between the national museums and a broader range of regional partners.
   • Museums' international roles will be strengthened to improve museum programmes in this country and Britain's image, reputation and relationships abroad.

The conservation profession response to this report was on the whole less than favourable, the Institute of Conservation (ICON) published their response under the title "A Failure of Vision".[44] It had the following to say:

No sector can look with confidence to the future if its key asset is worked harder and harder across an ever broadening range of objectives while the inputs required to sustain it are neglected.

It is of major concern to us that the only part of this section which makes any acknowledgement of the need for greater resourcing is the part which refers to acquisitions. The original consultation paper made quite extensive reference to the importance of collections, the role of new technologies, and cultural property issues, but this appears to have been whittled away in the present document.

Concluding:

When asked by the Commons Culture Media and Sport elect Committee CMS committee what he would like to see as a priority in the DCMS document arising from the 'Understanding the Future' consultation, Mr MacGregor responded 'I would like to see added there the need to conserve and research the collections, so that the collections can really play the role across the whole of the United Kingdom that they should.' So would we.

Further to this the ICON website summary report[45] lists the following specific recommendations:

• A national survey to find out what the public want from museums, what motivates them to visit them and what makes for a rewarding visit.
• A review of survey results and prioritisation of the various intrinsic, instrumental and institutional values to provide a clear basis for a 10-year strategy
• HR consultants to be brought in from the commercial sector to review recruitment, career development and working practices in the national and regional museums.
• A commitment to examine the potential for using Museum Accreditation as a more effective driver for improving recruitment, diversity, and career development across the sector.
• DCMS to take full account of the eventual findings of the current Commons Select Committee enquiry into Care of Collections in the final version of this document
• The adoption of those recommendations of the recent House of Lords inquiry into Science and Heritage which might affect the future of museums.

In November 2008, the UK-based think tank Demos published an influential pamphlet entitled It's a material world: caring for the public realm,[46] in which they argue for integrating the public directly into efforts to conserve material culture, particularly that which is in the public, their argument, as stated on page 16, demonstrates their belief that society can benefit from conservation as a paradigm as well as a profession:

conservators provide a paradigm not just for fixing things when they are broken, but for a wider social ethos of care, where we individually and collectively take responsibility and action.