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Daguerreotypes are on average 150 years old. Examples that have withstood the ravages of time are extremely rare. Yet a daguerreotype lasts much longer than most contemporary photographs. At least if it is protected from certain influences. Air and water, corrosion, mould, insects and above all people can represent a threat to the daguerreotype. The Nederlands Fotomuseum’s conservation studio is familiar with all sorts of forms of damage.
weaknesses
Photographs, including daguerreotypes, are primarily objects of practical use. Daguerreotypists and the makers of the cases did not regard the material as sacred. Not everyone dealt with a daguerreotype as though it were a museum piece. Even collectors, museum assistants and conservators did not always employ an ethics of restraint. However careful you are, it is crucial to know how vulnerable a daguerreotype is or can be and where its weaknesses lie. Damage can arise in three ways: mechanical, biological or chemical.
scratch away the silver
Mechanical damage is caused by physical force. Of course a daguerreotype can fall, so that glass and wooden parts break and the plate becomes deformed, but it can also be actively damaged. First of all, wear and tear are inevitable. In addition, many plates are scratched, probably because owners wanted to wipe them clean. Fingerprints regularly appear on the plate. Yet mechanical damage does not always have to be caused by a person. The deterioration of paper and glass can cause tiny particles to be deposited on the plate, penetrating the surface. Or the sharp edges of a mat can scratch away the silver unnoticed.
Mechanical damage to a portrait of an unknown person | Photographer unknown | Museum Joh. Enschedé, Haarlem
erosion of the cassette
Biological damage refers to organisms. Insects and mould can damage a daguerreotype, for example by eroding the cassette or by causing stains. Some organisms even lodge on the plate. (Strangely enough, man does not count as biological damage.)
substances and gases
Chemical influences, finally, form a major threat. They are difficult to perceive, are active almost everywhere and difficult to influence. ‘Ordinary’ air contains substances and gases that react with all sorts of material, certainly with paper, wood and metal. Oxidation, discolouration and dehydration are the result. The materials used for the housing can also include harmful components, such as acids or glue. Finally, treatment with the wrong substances can seriously damage a daguerreotype. It is a relatively short time ago that daguerreotypes were restored with ‘silver dip’ (thiourea), which in the long term could form a milky film on the image.
Results of a thiourea treatment on a portrait of an unknown woman | Photographer unknown | Private collection
the original form
The Nederlands Fotomuseum tries to restore damaged and changed daguerreotypes as much as possible to their original form. Unfortunately this is not always possible since it is difficult to determine the original condition. In addition, original cassettes usually have harmful and deteriorated parts which thus have to be replaced. The conservator then tries to change the outward appearance of the daguerreotype as little as possible. Modern materials are only used when absolutely necessary, which make the intervention clearly visible. The conservator thus prevents he object from being wrongly taken for an original.
electric current
When it is necessary to clean a plate, that is done at the Nederlands Fotomuseum by means of electrolysis. This involves laying the plate in a solution of ammonia through which a regulated electric current is then led. Electrolytic cleaning separates corrosion from the silver. Oxidation stains and other interventions with ‘silver dip’ can be removed almost entirely. If the plate has been painted or has not been gold toned (See the web article in this dossier under the title About the process), it can only be cleaned in a different way.
Construction of a preservation cassette | Nederlands Fotomuseum, Rotterdam
made to measure
In order to preserve the object in the best possible way a so-called ‘preservation cassette’ is made to measure. This consists of acid-free materials and ultra-violet resistant glass. The parts of the original cassette are usually combined with new parts which are hardly visible but provide much greater stability. Finally, the casing is sealed so as to keep out harmful gases.
compromise
Since daguerreotypes usually consist of a lot of different materials, a compromise has to be made when preserving them. What is best for the plate is less desirable for wooden or paper components of the housing. One of the least harmful solutions is to preserve them at a constant temperature of 18º C and a relative atmospheric humidity (RH) between 45 and 50 per cent. These are the ideal preservation conditions for paper and cardboard. What is also important is that a daguerreotype should always be stored flat and with the image side facing downwards. This should prevent any results of the decomposition of the glass from causing irreparable chemical damage to the plate.
meeting place
The conservation studio is a meeting place for photographic phenomena. Also for daguerreotypes. Owners of daguerreotypes, both public and private, turn to the Conservation and Restoration Department of the Nederlands Fotomuseum in order to have their collections of daguerreotypes preserved. The plates and their cases can differ greatly in appearance and quality. Having collected these divergent characteristics for many years, the department has established a source of information that is of international importance for research into daguerreotypes.
An example of the Daguerreobase interface | Nederlands Fotomuseum, Rotterdam
every detail
The Nederlands Fotomuseum began developing the Daguerreobase in 2004. This is a digital registration system specially for daguerreotypes, whereby each object’s external appearances and historical characteristics can be accurately described. During conservation daguerreotypes are generally taken apart and carefully documented. This is done in the museum both photographically and in writing. The conservator or registrar can now enter all the details that come to light directly into the Daguerreobase where they are stored centrally.
of unknown origin
For each component, however small, a separate description can be made. Every detail could include important information about the genesis of the object. Similarities between daguerreotypes from other collections, perhaps even originating from other parts of the world, can then be retrieved with a simple search operation.
attribution
To give an example: a conservation studio in the Netherlands is attending to a daguerreotype of unknown origin. It has a conspicuous mat and a hallmark of which little is known. The description of the mat yields similarities in the Daguerreobase with a series of objects from Hungary, all of which also bear the same hallmark. It is possible that the registrar there has a lot more information regarding the origin of the objects, perhaps even the name of the maker and of the person portrayed, a date and an indication of place. Conclusions can already be drawn on the basis of the information collected, as happened earlier with a series of daguerreotypes that could be ascribed to Carl Rensing, one of the first photographers established in the Netherlands.
Group portrait, ca. 1843-1855 | Photograph by Carl Rensing | Prentenkabinet Leiden
gain
The goal of the Daguerreobase is to provide access to the data of as many daguerreotypes as possible at a worldwide level. The Nederlands Fotomuseum regards every addition to the existing information as a gain. Normally speaking, daguerreotypes in museum collections are safely stored away. Unexpected relations between these collections seldom come to light, whereas they could indeed provide a missing piece of the puzzle for researchers. The Daguerreobase is intended to simplify research in the field of the daguerreotype and to offer an overview of this part of our global cultural heritage.
new facts
The Daguerreobase is meant for both interested laymen and specialised researchers. For the latter an independent website will be set up, making it possible to input data. The website of the Nederlands Fotomuseum will contain an extract of the most important information about most of the objects in the databank. Conclusions resulting from research will of course be included.
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