Monday, November 30, 2015

Preservation/Conservation

Preservation:
Activities associated with maintaining library, archival or museum materials for use, either in original physical form or in some other format. Preservation is a broader term than conservation: conservation activities form part of a total preservation program. Preservation includes both activities taken to repair or treat damaged materials (retrospective) and activities taken to prevent or delay material becoming damaged (preventive preservation). 

National Library of Australia. Library Prevention Glossary

Conservation:
The use of procedures to preserve and repair the physical structure of an item. All processes ideally should be reversible. 

National Library of Australia. Library Prevention Glossary

Causes of deterioration include

  • Changes in papermaking and binding practices
  • Acidity
  • Environment
  • Insect pests
  • Rodents
  • Fungus
  • Use and abuse by people
Changes in papermaking
Parchment: The split skin of an animal, usually a sheep, goat, or young calf, bleached, stretched, scraped, and prepared for use in bookbinding or as a writing or painting surface, from about the 2nd century A.D. until well after the invention of movable type.

Vellum: A thin, fine parchment made from the skin of a newly born lamb, kid, or calf, dressed and polished with alum for use as a writing surface and in bookbinding, before paper came into use in the 15th century.

 Reitz. ODLIS.

Paper

  • Early papers made from cotton and linen rags
  • 1830’s introduction of alum-rosin sizing replacing gelatin and gelatin-alum sizing
    • Breaks down over time to produce sulfuric acid which eventually causes paper to deteriorate and become brittle
Size (sizing)
Chemicals added to paper and board during manufacture to make it less absorbent, so that inks will not bleed, and the image will have better definition. Sizing can also be used to strengthen weak papers. Rosins, gelatin, starches and synthetic resins are used as sizing agents.. 

National Library of Australia. Library Prevention Glossary

Alum/rosin size
Chemicals added to paper and board during manufacture to make it less absorbent, so that inks will not bleed, and the image will have better definition. Sizing can also be used to strengthen weak papers. Rosins, gelatin, starches and synthetic resins are used as sizing agents.

National Library of Australia. Library Prevention Glossary


  • 1850 replacement of rag pulp paper with wood pulp paper
    • cellulose fibres of wood 10 times smaller and much more fragile than those of textiles

Acid paper
Paper which has a pH value lower than seven. An important factor in the preservation of printed materials, acidity causes paper to yellow and become brittle over time. To solve this problem, publishers are encouraged to use acid-free or permanent paper in printing trade books.

Reitz. ODLIS

Acidity
Paper can develop an acidic nature because of:

Preservation methods include:

  • Protective enclosures
  • Deacidification
  • Reprographic services
  • Digitization
  • Alkaline paper
  • Shelving
Protective enclosures
An example of a protective enclosure includes a phase box.





Double-tray box also known as a drop-spine or clamshell box.


Acid-free folders.



Encapsulation




Deacidification:
A common term for a chemical treatment that neutralises acid in a material such as paper, and that may deposit an alkaline buffer to counteract future acid attack. While deacidification may increase the chemical stability of paper, it does not restore strength or flexibility to brittle materials.
National Library of Australia. Library Prevention Glossary

Mass deacidification



  • No "ideal" mass deacidification process
  • Current systems and their users include:
Battelle Swiss National Archives
National Library Leipzig
Eschborn, Germany
Bookkeeper Library of Congress
Libertec Berlin & Munich State Libraries, Germany
Neschen State Archive of Lower Saxony, Germany
National Archive, Berlin, Germany
Wei T'o National Library of Canada

Reprographic services
  • Microfilming
  • Photocopying
    • least expensive
  • Photography
Digitization
Electronic digitization

Electronic digitization refers to the capture of the document in electronic form through a process of scanning and digitization. The scanned image can be made over the Internet, or stored electronically, usually on magnetic or optical storage media.


Wooden vs. metal shelves

From the perspective of preservation, it is best to store collections on metal shelving, since wood shelving can give off damaging pollutants. If wood shelving must be used, shelves should be sealed with polyurethane. Oil-based paints and stains should be avoided. In addition, shelves can be lined with museum board, polyester film, glass, Plexiglas, or an inert metallic laminate material to prevent materials from coming into direct contact with the wood.


Metal shelves should be powder coated electrostatically as other finishing processes may continue to give off fumes.


Environmental factors


  • Different records/media have different optimal environmental conditions
  • Paper usually forms the bulk of a collection of mixed archival materials so…
  • Guidelines for paper set the preservation norm
Environmental factors that can effect materials include:

  • Air quality
  • Dust
  • Light (ultraviolet most damaging)
  • Temperature
  • Humidity
Air quality

  • Primary sources of gaseous pollutants identified in deterioration of archival collections
    • Sulfur dioxide, nitrogen dioxide, ozone
  • Particular pollutants include grit, smoke, dust, etc.
  • Keep doors and windows closed
  • Use materials known to be benign to collections
  • Check and replace air filters/scrubbers regularly
  • Locate air intakes in as “clean” a location as possible
Light

  • All light damages archival material by fading, yellowing and structurally weakening them
  • UV light is more damaging, shorter wavelengths cause greatest amount of photochemical deterioration
  • Sunlight and fluorescent lights the two main UV light sources
  • UV filters e.g. acrylic sheets, film, foils, coatings
  • Storage area
    • Keep materials covered or boxed when not in use
    • Use blinds to eliminate sunlight
    • Apply UV filter film to windows
    • Select fluorescent tubes with low or no UV emissions or use UV filters on tubes
    • Turn lights off when area not in use
  • Storage area
    • Keep materials covered or boxed when not in use
    • Use blinds to eliminate sunlight
    • Apply UV filter film to windows
    • Select fluorescent tubes with low or no UV emissions or use UV filters on tubes
    • Turn lights off when area not in use
  • Exhibit area
    • Monitor area with lux and UV meters
    • Use copies whenever possible
    • Never have archival items on permanent display
    • Use a dimmer switch, lower watt bulbs or move light source further away
    • To reduce heat light source should not be inside or close to exhibition case
Relative humidity

  • Of primary importance in preservation of archival materials is providing a cool and dry storage area
  • In general, with every 5C increase in temperature, reaction rates double, e.g. archival records stored at 20C will have half the life expectancy of those stored at 15C
  • General rule of relative humidity:
    • When relative humidity is halved the life expectancy of the record is doubled
  • High relative humidity levels can lead to growth of mould and mildew, increased chemical deterioration, cockling of paper/parchment, warping of books, increase in likelihood of pest infestations
  • Low relative humidity leads to drying out of archival records making them brittle and susceptible to cracking


Environmental control standards


  • 1999 ASHRAE Handbook re-evaluated environmental standards for museums, libraries, and archives
  • A good compromise for a mixed collection 45% +/- 10% relative humidity and 18°C to 20°C
Other causes of deterioration

  • Insect pests
  • Rodents
  • Fungus
  • People
  • Shelving practices
References
Basic Conservation of Archival Materials http://www.cdncouncilarchives.ca/public_free.html


A Manual for Small Archives: Conservation and Security 
https://web.archive.org/web/20040310154328/http://aabc.bc.ca/aabc/msa/6_conservation_and_security.htm

European Commission on Preservation and Access. A Virtual Exhibition of the Ravages of Dust, Water, Moulds, Fungi, Bookworms and Other Pests. http://web.archive.org/web/20050306230604/http://www.knaw.nl/ecpa/expo.htm


NARA: Preservation http://www.archives.gov/preservation/


National Library of Australia. Library Preservation Glossary. http://www.nla.gov.au/chg/useful-resources/library-preservation-glossary


Reitz, Joan M. ODLIS http://www.abc-clio.com/ODLIS/odlis_A.aspx


Unesco. Safeguarding Our Documentary Heritage. http://webworld.unesco.org/safeguarding/en/


University of Illinois at Urbana-Champaign. Proper Care and Handling of Books and Paper Materials. http://www.library.illinois.edu/prescons/









No comments: