Long-term archiving: digital photography’s Achilles’ heel
Electronic photographs don’t have the staying power of older photography styles. How can you make sure your digital photo archive will last?
Published: June 20, 2011
Any system of archiving that depends on the regular interaction of the archivist is doomed to failure. So is there a failsafe way to store images? Using traditional photographic methods there is, but will digital last as long as your Kodachrome slides and properly fixed negatives? With CDs, DVDs, high-density hard drives, and now the “Cloud,” why should you worry? (See adjacent chart to start worrying.)
This chart illustrates the estimated lifetimes of different media. Click to enlarge.
The St. Maries River Railroad in northern Idaho ceased running log trains like this one in 2009. How long will this digital image documenting their operation in October 2008 survive?
Photo by Scott Lothes
All imaging media degrade and may disappear eventually, but some media disappear much faster than others; some within our lifetimes. Photographic and railroad technologies were invented and developed almost contemporaneously, and so we have a fairly comprehensive, well-preserved archive of railroad pictures dating back to almost the earliest railways, circa 1850. Pictures impressed on glass and metallic plates can still be viewed after a century and a half because their substrates and emulsions have deteriorated slowly. However, as photography has progressed from paper prints to today’s encoded digits, invisible to the naked eye, our expectations have diminished that digitized railroad images will still be readily available and viewable even a few decades from now.
The U.S. National Institute of Standards and Technology has studied recordable CDs and higher-density DVDs of the kind you record in your home computer. While mass-produced commercial disks encode data by creating dimples in the metal foil encased in a plastic package, your home variety encodes data via a photosensitive dye layered on aluminum foil. It may be digital, but it’s still a photographic medium.
The institute found a wide variance among disks, noting, "There was no guarantee that the media would last more than 10 years, … however, some failed within five years."
The reasons: The disk’s polycarbonate substrate may last forever, but its thin aluminum layer can oxidize or become lunch for microbes and its dyes will fade, especially if exposed to ultraviolet light. Higher-priced “gold” disks won’t oxidize, but advertised century-long lifespan doesn’t solve dye and mechanical issues. As for DVDs, the jury is still out. These disks’ higher densities will amplify any issues that occur with CDs.
This daguerreotype of Philadelphia & Columbia Railroad’s 1848-built Tioga remains a clear record of railroad in its earliest iterations.
Photo by Center for Railroad Photography & Art
Handling disks produces micro-fractures (you do use hard “jewel” cases to prevent bending, right?). While the data are somewhat redundant, with enough micro-fractures, content can become unrecoverable.
However, there is a more critical archiving issue for any “active” media (stuff that uses electronics or mechanics to be read) compared to “passive” media (things a human can see without electronic help). Electronic media depend wholly on plugs and sockets, and inscrutable computer programs and encoding algorithms. Standards change faster than diesel locomotive models, and there is no assurance that decades from now the multiplicity of often proprietary digital codes will be readily decipherable at reasonable costs, or at any cost.
Such planned obsolescence does not bode well when your great-great grandchild railfan opens your box of CDs or hard disks (or worse, a bunch of teensy camera chips) and has no clue as to what is on them, or what to plug them into. Videotapes made only a half-century ago cannot be read today by any working machine on the planet, and some early digital media can only be read by the machine that produced them (you keep all your peripherals in working order, no?). Compare that to 35mm motion picture film, which has not changed substantially in format in over a century, and can be at least scanned by the human eye. That is, if the film itself hasn’t completely disintegrated due to bad storage practices.
Lately, Web buzz has been all about the Cloud, online storage that will let someone else, for a fee, take the worry about digital files off your hands. The good news is that the Internet has evolved so you can store all your digits in cyberspace with one click and retrieve anything anywhere there is an active, accessible high-speed connection. The bad news is that you can store all your content in cyberspace and retrieve it anywhere there is an active, accessible high-speed connection, and so can anyone else who can hack the system. When the Cloud folks work out the details of security, up-time accessibility, and perpetual costs, this might be worth revisiting. Right now, we wouldn’t touch it for anything long-term.
The long-defunct Chicago North Shore & Milwaukee interurban passes 6th and National in Milwaukee. Black and white prints like this one hold their archival quality for decades.
Photo by Richard J. Solomon
So what do we recommend for archiving? Use multiple technologies for redundancy and insurance: a combination of hard drives and silver-based, passive, visual media.
Why hard drives and not tape? Magnetism will last millions of years, but tape substrates deteriorate quickly. With hard drives, if the mechanism isn’t damaged, data may be good for hundreds if not thousands of years — with this major caveat: you must keep everything in the chain. The (working) computer that wrote the data, the cable, plugs and software, and documentation in common language as to what is there and how to use it, must survive with it.
Black and white film on proper substrates (not nitrate), archivally processed and appropriately stored can last for a very long time (off our chart). And surprisingly, Kodachrome, including its original 1935 emulsions, and post-1988 Ektachrome have been shown via simulated aging tests to be stable for more than 40,000 (simulated) years. Assuming they are kept in the dark and frozen at minus 4 degrees Fahrenheit. But even at just above freezing, these films can last for thousands of years without degradation.
For your best photos, make archival prints, platinum or selenium-toned for black and white, or large-format silver-based color-separation negatives. Certain silver and digital color print processes, such as recent Kodacolor, Cibachrome, and pigment inkjet, can last for hundreds of years if stored in the dark. It is important that the papers must not incorporate “brighteners” that re-radiate ultraviolet rays.
Canadian National 4-8-4 6218 leads a fantrip through Quebec in October 1964. The slide is in mint condition, and is virtually unchanged from the day it left Kodak’s processing lab.
Photo by Richard J. Solomon
The bottom line is, if you really care about the long-term, store multiple copies of everything with full interfaces in different locations. Fire, water, earthquakes, and tornados are more destructive than bad plugs and media microfractures. And you can’t plan on copying content over and over again forever, which is why you want to archive it right the first time on media that will last as long as possible.
For more information on long-term storage, go online to:
Clark E. Johnson, Jr., is a physicist and magnetics expert, having developed some of the more advanced technologies in use today for high-density storage. He is a director of the Iowa Pacific, and operates the Caritas private car as High Iron Travel. |
Richard J. Solomon is on the research faculty at the University of Pennsylvania’s Moore School of Electrical Engineering, designing advanced electronic imaging systems. He maintains a full photographic darkroom as well as a digital color printing setup, and still prefers film over digital for archival railroad photography.
Johnson and Solomon are members of the Center for Railroad Photography & Art.
Full disclosure: the authors, along with colleagues at Creative Technology LLC, hold several patents and patents pending on advanced electronic imaging, spectroscopic, and networking technologies, and are actively pursuing the construction of an innovative, long-term digital and imaging storage apparatus. Stay tuned.