 | Back to 2. General Preservation Factors |
 | Up to Table of Contents |
 | Ahead to 4. Photographic Materials |
|
|
|
This group, with the greatest diversity,
contains the oldest materials. They are accessible with the naked
eye and the majority are made of materials which have the capacity
to last for a long time if cared for correctly. Many of the standards
cover a range of materials, and include details of the best storage
conditions.
The options for preservation range from
appropriate stable environmental conditions, through boxing and
packing, copying on to some other medium, to conservation. The
latter is the most expensive solution and can only be afforded
for a small number of items of particular importance. Each institution
or organisation will have to make its own list of priorities and
decide how best to afford appropriate protection to every category
of material. Basic protection, such as good housekeeping, training
staff to handle items with care, or storing them on shelving rather
than the floor does not cost much money and should be part of
every programme for preservation.
Microfilms can provide both an access
copy of original documents and also a safeguard against loss through
decay or disaster. If high fidelity microfilms are made, they
can also be used as the source for making digital copies.
Paper
Both Oriental and Western papers are
made using cellulose (vegetable fibre or materials made from such
fibres such as rags) and water, the former being beaten into a
pulp, dispersed in water and then drained through a tight mesh
mould. Once the water has drained away, the film of pulp remaining
on the mould is transferred to felts, dried and pressed to produce
a sheet of paper which may require further treatment depending
on the proposed use. While the original ingredients were relatively
pure the paper maintained good strength and longevity. However,
the introduction of wood pulp in the nineteenth century to satisfy
the increasing demand for paper led to a deterioration in quality.
Additives in the shape of alum, or alum rosin, chlorine, sulphate
of soda or other chemicals designed to speed the production of
the paper, or counteract the natural acidity of the wood, caused
more damage by breaking down the fibres which in consequence embrittled
the paper.
The reasons for the decay of nineteenth
and twentieth century papers are well known, but until recently
few solutions have been proffered. The adoption of rigorous standards
in the manufacture of paper intended for long term use is the
solution for the future survival of paper documents but does nothing
for those which already exist. Good storage, which includes boxing
archive and library material whenever possible, maintaining stable
environmental conditions, excluding light, keeping the store rooms
clean and dry and handling the material carefully contribute to
the overall preservation of these materials. The range of temperature
and relative humidity will vary according to the area of the world
but it is particularly important not to exceed 65% relative humidity,
the point at which mould growth is triggered. Specialist conservation
work, which involves treatment of the material, should be left
to trained conservators who will be able to assess the problems
of individual items. Mass de-acidification is used in some archives
and libraries but is not practised universally and is expensive.
Some modern papers used for copying or faxing are coated and
retain the text for a very short time only. These should be copied
as soon as possible using good quality paper.
Parchment
Parchment is made from the skin of an
animal, usually sheep but calf skin is also used. It consists
of collagen fibres, arranged in three dimensional bundles, which
are themselves proteins composed of long chain amino acids. The
skin is turned into parchment during a long process which involves
the removal of the fur and flesh with the use of lime, scraping
the skin, stretching it on frames to dry under tension, polishing
it and finally rubbing it with French chalk to provide a good
writing surface. It was the most common writing medium of the
Middle Ages in Europe, superseding papyrus by the third or fourth
century AD, until the invention of printing in the fifteenth century
increased the demand for a lighter, more flexible medium.
It is a very tough and versatile material
which, due to its nature, is hygroscopic. It reacts to external
temperature and humidity which must, therefore, be kept as stable
as possible. Excess relative humidity endangers the parchment
from both mould growth and deterioration but, by contrast, if
the parchment is too dry, the ink is likely to flake off. The
ink is also susceptible to being abraded by rough handling or
tensions induced by unstable environmental conditions. The range
of conditions for the survival of parchment are similar to those
required for paper.
Palm Leaves and Birch Bark
These materials are cellulose based,
being vegetable fibre. As natural materials, without the processing
involved in paper making, they are quite hard wearing but are
susceptible to cracking. The inks used are frequently carbon based
and may be endangered by incorrect storage, environmental conditions
or handling. The standards for these are similar to those for
paper and parchment
Standards
ISO NP 11799 | Storage requirements for archive and library materials |
ISO WD 11108 | Archival paper requirements for permanence and durability |
ISO/TC46 SC10 | Storage requirements for library and archival materials |
ISO/TC46 SC10 | Requirements for binding of books, periodicals, serials and other paper documents for archive and library use. Methods and materials |
ISO DIS 11800 | Information and documentation - Requirements for binding materials and methods used in the manufacture of books. |
ISO CD 14416 | Information and documentation - Requirements for binding of books, periodicals, serials and other paper documents for archive and library use - Methods and materials |
Reference Literature
Dureau, JN and Clements, DNG
Principles for the preservation and conservation of library materials
IFLA Professional report no 8 1986
Preservation of Historical Records
Committee on Preservation of Historical
Records, of the National Research Council of the National Academy
of Sciences. National Academy Press, 1985
Ellis, J
Keeping Archives
Thorpe and Australian Society of Archivists;
1993
Favier, J, Neirinck, D
La Pratique Archivistique Francaise
Paris, Archives Nationales, 1993
Ritzenthaler, ML
Archives and manuscripts
Society of American Archivists, 1993
UNESCO RAMP studies in general.
Available in Arabic, Chinese,
English, French, Russian and Spanish.
Also see the publications of the Commission
on Preservation and Access (Washington D.C. USA) and the European
Commission on Preservation and Access (The Hague, The Netherlands).
|
|
|