Top of page

Image of photographer Toni Frissell holding her camera surrounded by children
Toni Frissell, sitting, holding camera on her lap, with several children standing around her, 1945

Launching Units with Primary Source Phenomena: Micro-Scale Fade Testing

Share this post:

This post is by Jacqueline Katz, the 2022-2023 Albert Einstein Distinguished Educator Fellow at the Library of Congress.

What do you observe about this folder? What does it make you wonder?

Image of Blue folder with fading sections
Faded Folder by Jacqueline Katz

When my colleagues at the Library of Congress showed me this folder, we immediately started to talk about sunlight and degradation, and then transitioned into thinking about primary sources and preservation. This led me to visit the Library’s Preservation Research and Testing Division (PRD). It just so happened that Cindy Connelly Ryan, a Preservation Science Specialist, was testing a series of images to determine the risk of light degradation when exhibited. Cindy uses a micro-scale fade testing system (MFT), which combines optical fibers and lenses to focus light on a small segment of pigment or paper and a spectrophotometer to quantify the changes that occur.

Preservation Research and Testing Division’s MFT equipment for testing light sensitivity of primary sources. This 18th century watercolor is being assessed for inclusion in an upcoming exhibit.
Preservation Research and Testing Division’s MFT equipment for testing light sensitivity of primary sources. This 18th century watercolor is being assessed for inclusion in an upcoming exhibit. Image by Jacqueline Katz

A quick conversation with experts from the Library’s Prints and Photographs Division told me that not all primary sources were protected like the images Cindy was working with. Some photographs from the Toni Frissell Collection had been light damaged prior to arriving at the Library. Frissell’s collection contains over 440,000 items from her 40-year career as a photographer.

Image of small child in the snow
Swiss Children. Toni Frissell, 1948
Little boy with large red lollipop and small dog
Boy with Dog and Large Lollipop, Toni Frissell, 1948

Present students with these two photographs from the Frissell collection and ask them to observe, reflect, and question. Guide students to focus on the composition of the photograph rather than the content. Students will likely notice that the photograph labeled “Swiss Children” has a pink tint. Challenge students to hypothesize what might be causing the discoloration.

Students can test their hypotheses in the lab. Provide students with supplies to design their own experiment such as, different colored paper, different types of paper (computer, photograph, newspaper, tissue paper), various light sources (UV, LED, florescent, sunlight), printer, water, thermometers, card board boxes, etc. Student experimentation might result in the conclusion that certain dyes fade faster than others when exposed to light. In the Frissell collection photographs three dyes are present, yellow, red and blue. To create the pink tint that is observed in the “Swiss Children” photograph, it is likely that both the yellow and blue dyes degraded faster than the red either due to light exposure or time. To extend on this activity, students might conduct additional research to determine why certain dyes are more stable than others and practices that can be employed to avoid color degradation of photographs. These topics might fit well in a chemistry unit about light or chemical properties.

You can read more about PRD’s light sensitivity testing work in posts from the Library’s Guardians of Memory blog:

Preservation and conservation of primary source documents provide an interesting application of the concepts students learn in chemistry and physics. How might infusing primary source analysis in your classroom help to engage students?

Do you enjoy these posts? Subscribe! You’ll receive free teaching ideas and primary sources from the Library of Congress.

Add a Comment

This blog is governed by the general rules of respectful civil discourse. You are fully responsible for everything that you post. The content of all comments is released into the public domain unless clearly stated otherwise. The Library of Congress does not control the content posted. Nevertheless, the Library of Congress may monitor any user-generated content as it chooses and reserves the right to remove content for any reason whatever, without consent. Gratuitous links to sites are viewed as spam and may result in removed comments. We further reserve the right, in our sole discretion, to remove a user's privilege to post content on the Library site. Read our Comment and Posting Policy.


Required fields are indicated with an * asterisk.