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From the Stacks 

November 3, 2009

Nitrate negatives

A significant aspect of scientific expeditions is visually documenting

a location, people, or specimens. Here in the archive, it is our job

to preserve these images. While these days most scientists and

photographers are using digital cameras, which present their own

preservation issues, our earlier manuscript collections contain

physical photographs and film negatives. There are three types of film

base: cellulose nitrate, cellulose acetate, and polyester. Both

nitrate and acetate can break down over time and the fumes they

release can harm the collections around them. In fact, nitrate film,

first manufactured by Eastman Kodak in 1889 and continued to be made until

the early 1950s, is highly flammable. Nitrate film can be difficult to identify from

other film bases unless it is seriously deteriorated or clearly marked. The North East

Document Conservation Center has a wonderful preservation leaflet

about how to identify nitrate film and how to test if your film is


We didnt need to test this negative because it is marked Eastman - Nitrate - Kodak on the left edge.

We didn't need to test this negative because it is marked "Eastman - Nitrate - Kodak" on the left edge.

So, what can we do to capture the images on nitrate negatives and

still protect our other materials from fumes and possible fire? We are

in the process of a nitrate separation, digitization, and storage

project. As we find nitrate negatives, we digitize them by making a

high resolution Tiff image. This is our archival master image. The

negative is then placed in a paper enclosure and labeled in pencil. A

large group of negatives is put in an archival box, heat sealed in a

Marvelseal wrapper (to prevent moisture from getting in) and then

placed in a ziptop plastic bag. The bag is placed in our flammable material

storage freezer and kept at -20 degrees centigrade. This helps preserve

the image on the negative and protects our other collections from fumes

that nitrate generates as it degrades. So far, there are approximately

6,000 frozen negatives in our freezer and we have another 800

negatives to add to the freezer as part of our most recent project.

The images below are nitrate negatives that have been digitized in the

last year.

Election of Pope Benedict, 1914.

Gustav Eisen negative labeled "Election of Pope Benedict XIV 1914". Thanks to a comment from J.S. Oishi we know that election was actually of Pope Benedict XV.

Ynes Mexia negative of "Lake Mirror. Dawn." Yosemite National Park, 1921.

Danielle Castronovo – Archives and Digital Collections Librarian

Filed under: Archives,Photography — Archives & Special Collections @ 3:17 pm


  1. Great post! I just noticed that there appears to be a mistake in the original labeling of the Gustav Eisen negative: the date is 1914, but that was the date of the election of Pope Benedict XV, not XIV (http://www.vatican.va/holy_father/benedict_xv/index.htm). Benedict XIV was elected in 1740, long before the invention of photography.

    Comment by J. S. Oishi — November 3, 2009 @ 4:30 pm

  2. Glad you liked the post and thanks for letting me know about the Eisen label. Good catch!

    Comment by Danielle Castronovo — November 5, 2009 @ 1:21 pm

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