before 1800
Ancient civilizations used seven metals: iron, tin, lead, copper, mercury, silver and gold as ornamental objects, religious objects and weapons. Metals were important and protective conservation measures taken such as a copper pendant from northern Iraq dating to 8700 BC. C. and the gold objects from 4450 BC. C. from the Varna necropolis in Bulgaria were probably polished and valued as precious metals.[17].
The Roman bronze monument of Marcus Aurelius has several signs of conservation and restoration carried out since its construction in approximately 176 AD. C. .[18].
1800s and early 1900s
Before the late 1800s, treatments consisted of rebuilding and repairing the object by craftsmen familiar with the materials, and corrosion was thought to be a type of bacteria. At the end of the century, scientists began to seek to understand the causes of deterioration and corrosion. In 1888: Flinders Petrie (1853-1942) published an article on the excavation and conservation of small objects and the German chemist Friedrich Rathgen, (1862-1942), became not only the first director of the Chemical Laboratory of the Royal Museums in Berlin but was also the first scientist employed in a museum laboratory. Rathgen used electrolytic reduction to remove corrosive "Patina (copper)") from the Egyptian bronze collection at the Royal Museum to remove chloride salts. At the beginning of the century, the French chemist Marcellin Berthelot (1827-1907) presented several documents to the French Academy of Sciences in which he stated that the deterioration of bronze and silver objects was due to a cyclic process of corrosive chloride salts. Rathgen continued scientific research on bronze disease to understand the chemical conversion of the metal due to the presence of moisture. Rathgen applied a scientific method to the preservation of museum objects and by continuing to research, develop, apply and publish his findings on his physical and chemical methods and formulate guidelines for their application, he became instrumental in the acceptance of the standard. He is considered the founder of the modern science of chemical conservation and wrote the first complete and comprehensive conservation treatment manual to be published. Die Konservierung von Altertumsfunden [The Conservation of Antiquities] was first published in 1898, translated into English in 1905, and is still in print.[19].
During the bombings of World War I (WWI), museums protected their collections by moving them to various locations. Many entered the damp tunnels of London. After the war, the British Museum, which was lucky not to be bombed, reassembled the collection. After two years stored in high humidity conditions, the objects suffered severe damage from metal corrosion, mold, and salt efflorescence. The Department of Scientific and Industrial Research (UK) (DSIR) hired the Scotsman Alexander Scott (chemist) (1853-1947), as director of scientific research at what became the British Research Laboratory in 1920. In 1922, the curator and archaeologist Harold Plenderleith (1898-1997) became the first full-time chemist in a museum laboratory. Together they initiated the first scientific conservation in the UK while studying the instability of rapid deterioration. In 1934, Harold Plenderleith published “The Preservation of Antiquities” which contains vital information on the conservation of metals and the Agents of Deterioration that we know today.[20].
In the 1930s and 1940s, institutions in Western Europe and the United States recognized the need for prevention of objects before treating them and conducted extensive studies. Several large museums were adding research laboratories to their institutions. In 1931, the International Bureau of Museums of the League of Nations held its first conservation conference on applications of scientific methods in Rome. Precedent of the International Council of Museums (ICOM), which in 1946 held its first general conference in Paris in 1948.[20][21].
In preparation for World War II, museums once again placed art in underground tunnels, but this time the boxes were stacked to allow air circulation. The British Museum commissioned a secret climate-controlled tunnel in Aberystwyth to store works of art during the war. Moving and removing works of art and objects to stable and healthy environmental conditions allowed for minimal deterioration compared to World War I. Plenderleith, who treated the objects after the First World War, found no damage to the British Museum collection when they returned from the controlled environment tunnel.[22]
The United States' conservation efforts after the bombing of Pearl Harbor were disorganized and disorderly. Several museum directors believed in conservation and preservation. George L. Stout, founder of the first conservation laboratory in the United States and one of Europe's Monuments Men, was determined to create a long-term conservation standard. In 1949, his talk to the American Association of Museums conference in Chicago, “Long-Term Conservation,” posed the question “Why?” instead of “What? we conserve. This began the spread of a collective consciousness. As a result, in 1950 the International Institute for the Conservation of Historic and Artistic Works (IIC) was formed and Stout became its first president. In 1958, the ICC published an updated edition of H. J. Plenderleith's "The Conservation of Antiquities and Works of Art." One of the first systematic explanations of the mechanisms of deterioration including metals.[20][23].
In 1951, at the sixth session of the general conference of the United Nations Educational, Scientific and Cultural Organization (UNESCO), the Swiss government proposed the establishment of a global institution to promote conservation research and awareness. In 1959 Plenderleith became the first director of the International Center for the Study of the Preservation and Restoration of Cultural Property (ICCROM).[21].
The collective mindset for conservation and preservation changed the way museums and their directors approach collections. Two other metallurgy conservators are:
As a result of scientific research over the last 100 years, conservation has focused more on: preservation of the collection, control of the environment and agents of deterioration. The ICOM-CC metals working group conferences in 1995,[26] 1998,[27] 2001, 2004,[28] 2007, 2010,[29] 2013, 2016 and 2019 focused on metal conservation. These conferences have shed and will continue to shed light on the deterioration of metals. Provide information on the latest innovations in metal preservation and conservation treatment research and interactions with their environment.
The last thirty years have also emphasized minimalist conservation measures, but these treatment methods can often conflict with the use of the objects by visitors and sometimes researchers. The care of a collection is complex and now an interdisciplinary approach of concessions and commitments is needed, taking into account all the criteria with the contribution of everyone.[30].