Conservation and restoration of photographs

It is an umbrella term that includes both preventative preservation activities such as environmental control and conservation techniques that involve treating individual items.Both preservation and conservation require an in-depth understanding of how photographs are made, and the causes and prevention of deterioration.Conservator-restorers use this knowledge to treat photographic materials, stabilizing them from further deterioration, and sometimes restoring them for aesthetic purposes.Conservators will try to improve the visual appearance of a photograph as much as possible, while also ensuring its long-term survival and adhering the profession's ethical standards.Their understanding of the physical object and its structure makes them uniquely suited to a technical examination of the photograph, which can reveal clues about how, when, and where it was made.Photograph preservation does not normally include moving image materials, which by their nature require a very different approach.Physical photographs usually consist of three components: the final image material (e.g. silver, platinum, dyes, or pigments), the transparent binder layer (e.g. albumen, collodion, or gelatin) in which the final image material is suspended, and the primary support (e.g. paper, glass, metal, or plastic).Source:[2] 1816: HeliographyThe first person who succeeded in producing a paper negative of the camera image was Joseph Nicephore Niepce.He coated pewter plates with bitumen (an asphaltic varnish that hardens with exposure to light) and put them in a Camera Obscura.1837: DaguerreotypeThe daguerreotype process (named after Louis Jacques Mande Daguerre) produces a unique image, as there is no negative created.1841: CalotypeWilliam Henry Fox Talbot invented the negative-positive system of photography commonly used today.1850: Albumen printThis process, introduced by Louis Désiré Blanquart-Evrard, was the most common kind of print in the latter half of the nineteenth century.1858: Tintype (also called Ferrotype and Melainotype) In this photographic process the emulsion was painted directly onto a japanned (varnish finish) iron plate.The process rapidly spread and became a dominant method in Europe and America by 1894 since it had a visibly different color tone compared to albumen and gelatin silver prints.Vandyketype, or Single Kalliitype, is the simplest type of Kalltype and creates beautiful brown images.[9] Photograph stability refers to the ability of prints and film to remain visibly unchanged over periods of time.[20] Maintenance of a proper environment such as control of temperature and relative humidity (RH; a measure of how saturated the air is with moisture)[7] is extremely important to the preservation of photographic materials.Temperature should be maintained at or below 70 °F (21 °C) (the lower the better); an "often-recommended" compromise between preservation needs and human comfort is 65–70 °F (18–21 °C) (storage-only areas should be kept cooler).[12] Original prints, negatives, and transparencies (not glass plates, daguerreotypes, ambrotypes, tintypes, or other images on glass or metal) should be placed in packaging (archival folders in board boxes in double freezer weight Ziplock bags) in cold storage, and temperatures should be maintained at 1.7–4.4 °C (35.1–39.9 °F).Hanging photographs on a wall can cause damage from the exposure to direct sunlight, or to fluorescent lights.[12] UV-absorbing sleeves can be used to filter out damaging rays from fluorescent tubes and UV- absorbing sheets can be placed over windows or in frames.[12] Foods, drink, dirt, cleaning chemicals, and photocopy machines should be kept away from photo storage, exhibit, or work spaces.Storage materials must pass the ANSI Photographic Activity Test (PAT) which is noted in suppliers’ catalogs.[12] Plastic is not suitable for prints with surface damage, glass or metal-based photographs, nor for film-based negatives and transparencies from the 1950s, unless the latter are in cold storage.Only the positive prints survive, owing to the widespread practice of recycling the original glass negatives to reclaim the silver content.As defined by the American Institute for Conservation, treatment is "the deliberate alteration of the chemical and/or physical aspects of cultural property, aimed primarily at prolonging its existence.Additionally, members of other professions (such as archivists and librarians) who deal with preservation of photographs do so in accordance with their professional organization's codes of ethics.The International Federation of Library Associations and Institutions has published a list of ANSI standards pertaining to the care and handling of photographs.