Microfilm Preservation in a Digital World

Digital technology opens archival materials to worldwide access, but it may not stand the test of time. Issues of life expectancy, authenticity, initial cost, and ongoing cost remain unsolved for digitized documents. Archives are responsible for long-term collections care, so must choose preservation strategies wisely. For most repositories, including the Hoover Institution Archives, microfilm is still the best medium for long term preservation.

The U.S. National Archives and Records Administration (NARA) continues to use microfilm for preservation purposes because

Hoover Preservation Officer Gary McLerran works on digitizing microfilm

Microfilm is a low-cost, reliable, long-term, standardized image storage medium. The equipment needed to view microfilm images is simple, consisting of light and magnification. The medium has a life-expectancy of hundreds of years. Digital images, on the other hand, consist of a wide variety of machine codes that require computer hardware and software to be made visible. To avoid the obsolescence of changing computer technology, digital images must be reformatted periodically. The cost of maintaining microfilm is small compared with that of digital images. Microfilm only needs shelving in a cool, dry place for a very long period of time. 1

Life expectancy. Most U.S. preservation officers agree “digitization does not constitute preservation.” 2 The Library of Congress (LC) is retaining microfilm or paper copies of digitized documents until it is confident that digital data will last as long as the analog version. 3 Digital information has 1/100 the life expectancy of microfilm (5 years vs. 500). 4

Authenticity. Digital documents are vulnerable to accidental or deliberate change, corruption, or erasure, and they have no history of legal acceptance. They “are continually at risk of inadvertent or intentional alteration, and such alteration may not be readily perceptible.” 5

Initial cost. Digitizing appears to cost more than microfilming, though accurate cost figures are hard to find. 6 Existing cost estimates vary widely and depend on variables such as the original material format and digital specifications, but a study that averaged costs of NARA, LC, and other digitization projects found an adjusted average digitizing cost of $17.65 per image, with an average of 25 images produced per day. 7 Digital conversion, metadata creation, and other activities (including quality control and administration) each account for about one-third of the total. Current Hoover microfilming costs are about $0.40 per image. 8

Ongoing cost. After creation, the “costs of preserving electronic records will be high and will extend over a long period.” 9 In the first ten years, maintenance costs for one set of offline master files and online access files is 50 to 100 percent of the initial investment. 10 It is clear that for digital preservation to be affordable, new business models are needed. 11

Access. Digital technology is universally viewed as a method for improving access. 12 Hybrid digital/microfilm projects that use each technology to its best advantage are the most viable approach. 13

For additional information please contact Preservation Officer Gary McLerran at (650) 723-5018 or by e-mail mclerran@hoover.stanford.edu.

Endnotes

1 All documents accessed March 18, 2004.
NARA , “Microfilm.” Available at http://www.archives.gov/preservation/archival_formats/microfilm.html .

2 Janet Gertz, “Selection Guidelines for Preservation,” Joint RLG and NPO Preservation Conference: Guidelines for Digital Imaging, September 28-30, 1998 . Available at http://www.rlg.org/preserv/joint/gertz.html .

3 LC, Preservation Reformatting Division, “Principles and Specifications for Preservation Digital Reformatting.” Available at http://lcweb.loc.gov/preserv/prd/presdig/presprinciple.html .

4 Steven Puglia, “Analog vs. Digital for Preservation Reformatting,” NARA 18th Annual Preservation Conference: Preservation Reformatting: Digital Technology vs. Analog Technology, March 27, 2003. Available at http://www.archives.gov/preservation/conferences/papers_2003/puglia.html .

5 International Research on Permanent Authentic Records in Electronic Systems (InterPARES), Authenticity Task Force Report, n.d., p 2. Available at http://www.interpares.org/display_file.cfm?doc=ip1_atf_report.pdf .

6 Gertz, “Selection Guidelines for Preservation.”

7 Steven Puglia, “The Costs of Digital Imaging Projects,” RLG DigiNews 3 , no. 5 (October 15, 1999). Available at http://www.rlg.org/preserv/diginews/diginews3-5.html .

8 Conversation with Hoover Preservation Officer Gary McLerran, March 18, 2004.

9 Shelby Sanett, “The Cost to Preserve Authentic Electronic Records in Perpetuity: Comparing Costs across Cost Models and Cost Frameworks,” RLG DigiNews 7 , no. 4 ( August 15, 2003 ). Available at http://www.rlg.org/preserv/diginews/v7_n4_feature2.html .

10Puglia , “Analog vs. Digital for Preservation Reformatting.”

11 Library of Congress and National Science Foundation, “It's About Time: Research Challenges in Digital Archiving and Long-Term Preservation,” August 2003, final report, Workshop on Research Challenges in Digital Archiving and Long-Term Preservation, April 12-13, 2002, p. ix. Available at http://www.digitalpreservation.gov/repor/NSF_LC_Final_Report.pdf .

12NARA , “Microfilm,” and Gertz, “Selection Guidelines for Preservation.”

13Puglia , “The Costs of Digital Imaging Projects.”