Proper packing and storage of objects and associated records is essential for their long-term preservation. Poor storage, involving the containers, shelving, and storage environment, has probably been the biggest factor in the deterioration of many archeological collections over the last hundred years.
In the field, the principal investigator and archeological staff should try to use stable and long-lived materials for initial packing of objects. Often these "temporary" containers house objects and records for years. Consequently, they should also be labeled immediately. Using containers of stable materials, especially those of archival quality, at the start of a project can save time and money that otherwise will have to be spent later on rehousing the collection.
In general, until it is assessed, stabilized, and prepared for permanent storage, an object should be kept in a storage environment that closely resembles its in situ conditions. Records should be kept in a storage environment that minimizes deterioration from significant fluctuations in temperature and humidity, water leakage, and pest infestations.
Once initial analysis and processing of an object, object lot, or group of records is complete, the item, lot, or group should be placed in appropriate long-term housing. For artifacts, an artifact container, such as a bag, box, or sleeve made of acid-free paper or plastic, is the receptacle that holds one object. For associated records, such a container is usually a file folder. A storage container, such as larger boxes, drawers, and cabinets, holds numerous artifact containers or record file folders.
The type of artifact, records, or storage container used is based on a number of criteria. These include:
The type of storage and/or artifact container used may also depend on funding and space limitations. Unfortunately, few repositories have the space or funds for ideal packaging and storage of all the material remains and associated records they manage. At the very least, it is important for all objects to be fully supported and have readily visible, proper provenience data on the containers. In some cases, objects and/or records should not touch each other (see above). For example, never store colored papers, ink, photos, or maps directly next to buffered paper.
Once a storage container is selected to house a number of objects or records and the packing is completed, it may become necessary to remove an item to rehouse it in another sized container. If this is done, it is important to carefully document the removal from the original container and identify the new location.
Below is a table of materials that should and should not be used for packing and storing material remains. In general, containers should be self-closing. Rubber bands, twist ties, tape, string, staples, or heat sealing should not be used to close containers.
Specific Notes on Associated Records
The biggest challenges for associated records involve using the correct storage materials for particular types of records in association with a good storage environment (see also next sub-section).
Paper records should only be stored in archival quality housing, particularly paper, folders, and boxes with a neutral pH. Items should be unfolded and most paper records should be stored vertically in folders within storage boxes. Oversize items should be stored flat to avoid sagging.
Temperature and relative humidity (RH) should be kept within proper ranges in order to prevent mold or the embrittlement of paper. A good temperature range for paper records is between 60-75 °F and a good RH range is between 40-55%.
All metal fasteners (paper clips, staples), rubber bands, and adhesives (post-it notes, tape, adhesive labels) should be removed from individual records. Since the deterioration of such fasteners can leave residues on the records and cause further harm to the material, any damage and loss of information should be carefully recorded.
Different copying and printing processes also require special storage and conservation needs. Blueprints and newsprint should be stored separately from other paper because they are chemically unstable. Older copying processes, such as carbon copies or Photostats, deteriorate and fade rapidly. They should be copied onto archival quality materials. If a record is separated out for any reason, a separation sheet should be inserted that indicates the new storage location.
Packing and storing photographs, negatives, and slides differ somewhat from the methods and materials used for paper records. Photographs should be stored in individual sleeves that are non-buffered, have a neutral pH, and are made of archival quality paper or inert plastics, such as polyethylene. Vertical, supported storage containers should also be used.
Cold storage with a low RH are good for photographic materials that do not require frequent or regular access (no more than once a year) -- an RH between 20-50% and temperatures at 35-40°F. If photographs are placed in cold storage, the temperature and RH must be closely aligned in order to prevent condensation. Also, inert plastic sleeves should not be used to house individual photographs in cold storage.
More specific storage and conservation needs are dependent on the film processes used. Black and white pictures are much more stable than color. Older film, such as cellulose nitrate and cellulose ester films are highly unstable. Nitrate film can also be very combustible. Separate cold storage and copying of these materials is necessary. Badly deteriorated film should be disposed of since it poses health, safety, and fire risks.
The relatively recent widespread use of electronic and digital media, such as computer diskettes, magnetic tapes, and compact discs, have resulted in some interesting research concerning their preservation and storage. Guidelines for the life expectancy of these materials and how best to take care of them are now available. In general, electronic or digital media should be stored in a dust free environment and away from any magnetic fields. Storage in inert plastic containers and in a vertical position are usually the best. These materials are sensitive to temperature and RH fluctuation, especially excessive heat. (CDs are more prone to RH problems.) A range between 62-68 °F and 30-40% RH is acceptable. Tapes should be rewound and refreshed periodically to ensure viability. Magnetic media should be copied at least every five years. Digital media should be continuously migrated to newer file formats in order to be compatible with newer software and hardware.
As Eiteljorg (1998) emphasizes, however, archeological data in digital format may become relatively useless, despite migration and reformatting over time, if the creator of the data does not provide complete and timely supporting documentation about the data and its structure. This includes file names, relationships between files, data standards, the methods used to compile the data, and level of data accuracy. This supporting documentation, called metadata, must be stored with the digital data.
Rapid technological changes also affect digital records. Much electronic and digital archeological data created five-ten years ago are now in non-current formats that cannot be accessed by contemporary hardware and software. Time and funds now have to be spent on migrating data to new formats and purchasing or maintaining compatible hardware and software to read and use the data. When digital records and data are upgraded and transferred to new software or hardware specifications, they should be tested immediately for completeness of the transfer. For magnetic media, playback equipment must be kept in good condition. Because of their short use life and short conservation life span, it is advisable to make copies of magnetic and digital records on other media, such as paper or microfilm. Any copies made should be placed onto longer-lived media than the original.
Here is a table of materials that should and should not be used for packing and storing associated records.