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Photocopy technology emerged from machines developed
for business purposes and taken up by librarians to
duplicate missing, scarce, and deteriorating materials.
Librarians photocopy materials to replace missing pages
from books and missing issues from periodicals, and
to increase the copies of items in high demand. The
latter practice is, of course, illegal unless the materials
are out of copyright. Photocopying to replace brittle
books, however, is regarded as fair use if the library
owns the titles involved and makes only one copy to
replace the compromised original.
Preservation
photocopy is copy made with a high-quality
machine that is maintained in good enough condition
to produce well-fused images (images that will not smudge
or be picked up when a piece of pressure-sensitive
tape is touched to the surface). The
paper must be permanent/durable
(acid free and buffered), and the image must be the
same size as the original, and on both sides of the
leaf with good registration. When replicating a brittle
book, most expert copiers will construct a paper frame
to obscure the black lines that would otherwise show
around the original page edges and that will center
the image on the copy paper. Generally, the photocopy
facsimile will be bound using double-fan adhesive
techniques with an inside gutter margin of no less than
3.7 centimeters.
Once they are discovered after circulation (see CONSERVATION:
BASIC REMEDIAL TREATMENT: Books), books with brittle
paper are usually replaced by preservation
photocopy unless there are other copies
available (for example, large sets or serials on microfilm,
or reprints or new editions). Few guidelines have been
developed for preservation photocopy beyond ensuring
that the paper will last, the image is stable, and the
final product replicates the original volume as closely
as possible.
Photocopy machines are now available that can produce
accurate color copies and excellent black and white
copies. A color copier can also produce a quality gray-scale
image, rendering an old black and white photograph extremely
accurately. For this reason, quality photocopy is used
increasingly to produce surrogate facsimile copies of
original documents and photographs for readers and for
exhibition. This is important when the original might
be damaged through too much handling or is too light
sensitive to be placed on display.
Older photocopied materials may have badly deteriorated
because of unstable chemicals used in image production
or poor-quality paper. Materials produced by old processes
such as mimeograph and Ozalid wet process are undoubtedly
faded and should be re-photocopied with modern equipment
on good paper. Information on these processes may be
found in the following:
• The Dead Media Project, http://www.deadmedia.org/
• The Early Office Museum(tm), http://www.officemuseum.com/copy_machines.htm
• Peter Graham, "Mimeograph and Its Competitors,"
http://palimpsest.stanford.edu/byform/mailing-lists/exlibris/1995/05/
• Kevin Laurence, "The Exciting History of
Carbon Paper!" 1995, http://www.kevinlaurence.net/essays/cc.shtml
• Melbourne Museum of Printing, Glossary of Printing
and Typography, http://home.vicnet.net.au/~typo/glossary
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Photocopy 
