In addition to an item list, it is important to record, wherever possible, how and when a collection was acquired and any conditions affecting the HER's rights over its contents, such as copyright, database right or licences for making reproductions of the material for third parties. These conditions may be set out in a deposit licence or through an exchange of letters between the HER and the originator of the material, whether reports, plans, drawings, photographs, digital data, written notes or simply a letter.
The guidance for paper and plastics is relevant to photographic materials but an added problem is that the layers react differently to changes in relative temperature and humidity and can separate. Light is especially damaging as the image-bearing emulsion continues to react chemically, and over time the image may be lost. Chemical deterioration of the base material is another problem:. plastics are unstable and poor washing of photographic prints can leave chemical residues in the paper base which cause decay. The gelatine in the emulsion contains nutrients which, in poor conditions, can be used as a food source by fungus, insects and even rodents. Photographic materials should never be stored in the bags or packages in which they come from photographic printers (these are made of lowgrade papers and absorb processing chemicals).
When cataloguing it is important to consider the lifespan of the collection, that is, how long do you anticipate that the HER will retain the material? If the material is destined for permanent storage as archival material, HER managers are recommended to consider whether the original material should be deposited at a museum or record office and a copy retained for HER use. For materials that the HER does retain, those with the longest lifespan should be treated to the best possible storage conditions. Some items may have a fixed useful life, for example a map series may be superseded by a later edition, these items may be stored to lower standards and removed when no longer required. Continuing to store items beyond the end of their useful life can have an adverse impact on the management of higher-priority collections.
For items that may be 'borrowed' from the HER for any period of time it is also important to have some form of movement control. At the simplest level this means maintaining a signing-out book and monitoring this to make sure that items such as library books or lecture slides are returned.
Shelves are conventionally used to store books, pamphlets, magazines and other materials. These must be loaded carefully so that material is evenly distributed both across the length and from top to bottom. Overloading the top shelves causes instability. Packing items too tightly on a shelf can cause damage through friction or distortion.
Large books may be better stored on their sides and fully supported by the shelf. Be aware that heavy stacks may cause undue pressure on those items at the bottom. Books that are stored upright are best supported by a bookend when shelves are partially filled. Pamphlets, thin booklets and photographs may be grouped together in archive or magazine file boxes.
Maps, plans and drawings are best stored flat resting horizontally in drawers or shelves. They may also be suspended in plan chests but this form of storage is better avoided as it can cause stretching or distortion.
Wooden drawer units may be in use but HER managers should be aware that these are a potential fire hazard. Another disadvantage is that acid from the wood can have a detrimental effect on paper materials stored within the drawer units.
Filing cabinets are conventionally used in HERs to store parish and supplementary files, correspondence and photographs. As with shelves, these should be loaded evenly and care taken to avoid overfilling.
Arrangements should be made for the storage of the digital outputs of archaeological fieldwork and research so that they can be effectively managed and preserved, ideally with a trusted repository. Archaeological Grey Literature, for example, can be added to OASIS http://oasis.ac.uk from where it will be deposited with the Archaeology Data Service http://archaeologydataservice.ac.uk/ and made available in the Grey Literature Library http://archaeologydataservice.ac.uk/archives/view/greylit/. At the same time, provision should also be made for the other digital outputs of fieldwork. For specific advice see Section B.10.7 Digital archiving below.
Archivists use conservation-grade 'acid-free' paper to wrap or separate paper archives. These papers are treated during manufacture to provide a neutral buffer that protects the archive from dirt and other environmental pollutants. HER officers should note that paper that is described as 'wood-free' cannot also be assumed to be 'acid-free'.
Polyester sleeves are also used to offer protection against dirt, but if used, these should be of conservation-grade materials. PVC is not a suitable storage material for films or photographs as it is chemically unstable and will cause damage to archives.
Care should be taken in fastening archives together. Archivists use brass clips as normal office paper clips, pins and staples are made of steel and rust over time. Sticky tapes and glues are best avoided as they are chemically unstable and deteriorate over time, causing stains.
Marking archive collections with identification numbers can cause damage. If collections are to be marked then a soft pencil should be used as ink can bleed into paper, and a number written on the back of a document or photograph can become visible on the front over time.
Fireproof safes or cabinets may be used to store computer discs, tapes and other electronic media.
Light accelerates the chemical decomposition of a range of materials, fades inks and dyes and causes plastics to deteriorate. All photographic materials are light sensitive. Both daylight and electronic light contribute to the problem. Windows and other light sources can be screened with UV filters which will need to be periodically replaced as the quality of the filtration decays over time.
Atmospheric pollutants, such as acidic gases, can damage paper and plastics and change colours in pigments. Strong cleaning materials and solvents give off atmospheric pollutants and should be stored well away from collections, particularly plastics.
Biological agents, such as bacteria, insects and mould flourish under conditions of high humidity and temperature. Mice and birds can also get into store rooms and cause obvious damage.
Contact with poor-quality materials may also cause damage: for example chemicals can leach through from a poor-quality mount into a map or print. Yellow stains can be caused by glue or adhesive tapes and these are impossible to remove. In general, combinations of materials (such as plastics and paper) accelerate chemical degradation.
It is recommended that you do not allow people to eat, drink, smoke or use ink pens while they are consulting the HER collections.
Alliance of Museums Libraries and Archives http://almauk.org/
Museum Net (products & services) http://www.museums.co.uk/products/default.asp
Museums Association http://www.museumsassociation.org
Research has been undertaken into the preservation and reuse of digital data by a number of organisations including the ADS. A number of archiving strategies have been identified:
Generally, data archivists consider that migration is the only viable long-term solution to preservation. The costs and implications of long-term digital archiving are considerable. The timescales and the complexity of migration routines together with the need for secure deep storage facilities can only be provided by specialist data-archiving organisations. The ADS is one such organisation that has been set up to ensure preservation and to maintain data access.
Recent thinking is towards moving data into standardised formats based on XML (see B.11.4). The CAMiLEON project developed a demonstrator tool that migrates drawings created with proprietary software into the XML-based SVG (Scaleable Vector Graphics) format. Similarly Xena, open source digital preservation software developed by the National Archives of Australia, undertakes the ‘XML Electronic Normalising of Archives’. Xena uses a plugin architecture to handle various formats.
The use of XML for long-term archiving of digital data is also an objective of the FISH Interoperability Toolkit project (see B.6.4). The MIDAS XML schema which lie at the heart of the Toolkit, have been developed in line with recommendations of the World Wide Web consortium. They provide a suitable XML format for the storage of text data output from typical Historic Environment Records. No special software is required to access XML files: they can be read with standard PC accessories such as Notepad, Wordpad or recent versions of Internet Explorer.
A major archival function is the categorisation and description of datasets. Such metadata (see B. 11.3) is used to describe both the data format/medium and the content of a resource. The former aids preservation strategies while the latter helps in locating and accessing a desired resource. Of late much research has gone into agreeing metadata standards, such as the Dublin Core, in order to promote accessibility and to facilitate the use of distributed resources.
Storage of data, in either digital or printed (hard copy) form, within a records management system such as a HER does not correspond with curating the same material within a recognised archive.
HERs are receiving greater amounts of digital data, such as fieldwork reports in .pdf format, and ever growing quantities of digital images, especially from the increased use of digital cameras. At the same time, HER’s often create digital data, such as word documents, databases, and GIS files, as part of their own projects. These all take up increasing amounts of disc or server space and in turn may merit curation as part of a digital archive to ensure their long-term preservation and accessibility. HER managers should consider which parts of their collections will require digital archiving and may need to seek the advice of their host organization regarding their storage and archiving whilst maintaining access to these files. Alternatively, it may be necessary to look at options for depositing these digital files with appropriate local archives or national bodies such as the ADS, who can host the files as part of their archive and allow access to them via a web link.
FISH Interoperability Toolkit http://archaeologydataservice.ac.uk/fishtoolkit/
RCAHMS digital archives guidelines http://www.rcahms.gov.uk/freedom-of-information.html