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Photograph Preservation

Behind-the-Scenes of

Deep in the Philadelphia City Archives, in a little clearing surrounded by an almost uncountable number of boxes, sit a couple of tables, a handful of computers, and several dedicated interns. Together with the staff of the Philadelphia Department of Records, these energetic interns are working to preserve Philadelphia's past one photograph at a time. Five days a week, this little space amid the stacks hums with the sound of scanners as the interns digitally preserve each photo by scanning and uploading it to, and then re-housing it in an acid-free envelope.

How does one negative stored in a brown cardboard box on Shelf 2726 make its way onto How does a photograph that sat unseen for decades suddenly become viewable online by anyone with access to an internet connection? Discover why preservation is so important and how you can help the City of Philadelphia to preserve its history everyday. Welcome to the behind-the-scenes world of!

Looking down a long hall of image boxes at the archives.


Challenges and Solutions

Preserving photographs starts with answering one basic question: what do we have? For the Philadelphia City Archives, the answer is a lot of photos! With an estimated two million photographs, the interns have their work cut out for them, but they keep moving forward one box at a time.

Storage Box before scanning.

With literally millions of documents and photographs in the City Archives, it's difficult to ensure that every box is perfectly organized. When the interns open a box of negatives like this one, they must determine how they are arranged. And, no, scattered is not an arrangement! Each negative has an individual number that identifies it as part of a specific group of records such as Public Works, Schools, or Department of Streets. The interns carefully examine each negative and its envelope to find important information about that negative.

Collectively known as "metadata", the information from the envelope can include the date, title, photographer, and location where the photograph was taken as well as the record group and number of the negative. The interns create a record on for each negative and then enter all the metadata relating to that negative. While not all of the photographs have every piece of information, many of the envelopes note where the photo was taken. Geocoding (entering the location, i.e. longitude and latitude, into a mapping feature on makes it possible to search for that photograph by address - one of the most helpful and unique features of the website. After entering all the available data, the interns scan the photo and upload it to the previously created record on Then, with one simple click of a button, a photograph that was buried in the archives for decades is suddenly available on the internet around the world.

The digital preservation of the photograph does not end there. In addition to placing the photo online, the interns convert the original scan of the photograph into high resolution and medium resolution versions. They store the medium resolution on a server that is accessible by the City Hall Photo Unit, the group that processes purchase requests for photographs. The high resolution images are burned onto CDs which are then labeled and carefully stored on shelves at the archives. The photograph now exists in three different digital forms, ensuring that the image is safely preserved and easily accessible.

Storage Box after scanning.

After successfully digitizing the photograph and placing it online, the interns also tend to the preservation of the physical negative. They place the negative in a new archival quality, acid-free envelope that contains all the information from the old envelope and then file the envelopes numerically in archival quality, acid-free boxes. As demonstrated here, the finished product is a well-organized, labeled, and easily locatable box of negatives.

These boxes are then stored in a temperature and humidity controlled, secure environment. The image is now both digitally and physically preserved and protected from deterioration and destruction.


Photographic Triage

Sometimes, though, the interns are too late. The passage of time has already done its damage. Negatives capture one quick moment of life, but without the proper preservation measures, they are at risk for irreparable deterioration.

Time-damaged negative.

Dating from the 1950s, this negative is made from a substance called cellulose acetate film or safety film. When acetate film came into use in the early twentieth century, it was seen as a great improvement over the previously used nitrocellulose film - a film type which had a tendency to spontaneously combust! Acetate film, however, has serious deterioration problems as shown by this negative. In a process called channeling and shrinkage, the layers of the photograph separate and start to buckle and bubble. Even storage in the temperature and humidity controlled rooms at the City Archives can only slow rather than stop the deterioration of this negative that is less than sixty years old.

How do we save the image on this negative? Despite its appearance, this negative is still stable enough to be digitally preserved. With utmost care, the interns scan the negative, place the image on, and then save digital copies of the image in two different locations for safe-keeping. The bubbling on the negative will cause faint white lines on the scan, but the creation of a digital version of the photograph ensures that the negative now exists in a form that can never deteriorate.


PhillyHistory's Crucial Role and How You Can Help ...
... One Picture at a Time


Intern's work station.

Where does all of this preservation magic happen? Right in the middle of the archives. With just a few computers and scanners, the interns help add several hundred new photographs to every week.

It's a simple enough process.

  1. Open box
  2. Remove negative
  3. Enter data into database
  4. Scan negative
  5. Place negative into new acid-free envelope
  6. Place envelope into new acid-free box
  7. Upload photograph onto
  8. Save scanned image at a medium resolution
  9. Save scanned image at a high resolution
  10. Repeat
  11. Repeat
  12. Repeat ... ...

One photograph at a time, the interns of are shining a bright light on Philadelphia's past and giving a new level of accessibility to an amazing archive of history. But the users who purchase photographs from the website also help with this monumental task. Indeed, the funds collected from photograph sales on the website go back into the project to ensure that the interns can continue scanning the nearly two million images in the City Archives collection. is a crucial part of the preservation of the photographs. By digitizing the negatives in their collection, saving the scanned photos on servers and CDs, and re-housing negatives into an acid-free environment the Philadelphia City Archives is guaranteeing that this visual record of the city's history remains safe and accessible to the public. Besides helping with digital preservation, the interns are also assisting with the preservation of the physical copy of each negative. Without these efforts, the enemies of preservation - light, heat, humidity, temperature change, chemical degradation - would slowly cause permanent damage to irreplaceable photographs.

Thanks to, the Philadelphia Department of Records, the interns, and dedicated users any fears about forever losing the photographic keys to the city's past can be forgotten.

Collections that look like this:

Archive shelf before scanning.

Are being turned into collections that look like this:

Archive shelf after scanning.

And what was once damaged and inaccessible:

Time-damaged negative.

Can now be easily viewed and preserved on

Scanned image from damaged negative
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