Conservation photodocumentation at the Library of Congress

Today’s guest post is from Gwenanne Edwards, Senior Paper Conservator in the Conservation Division at the Library of Congress. Gwenanne is the current head of the Conservation Division’s Image Documentation Committee, which develops protocols for staff conservation photodocumentation.

The Digital Imaging Workflow for Treatment Documentation, an instructional manual for conservation photodocumentation used in the Conservation Division at the Library of Congress, is now available online.

When special collections materials are selected for conservation treatment, conservation staff first record the object in its current condition through written and photographic documentation. Photodocumentation serves several purposes:

  1. As a tool for examination, where capturing the object in various lighting conditions and wavelengths can highlight certain condition issues and/or help characterize materials;
  2. As a permanent record of conservation treatment, where capturing the object before and after treatment in the same photographic conditions allows for comparison;
  3. For reference during conservation treatment.


Two conservators stand over a table tophotograph an early photograph of Harriet Tubman

Conservators Alisha Chipman and Jennifer Evers photograph the Emily Howland album, containing an early photograph of Harriet Tubman, before conservation treatment. Photo by Shawn Miller.

Although the Digital Imaging Workflow for Treatment Documentation is specific to the setup and equipment in the Conservation Division, the procedures in the manual may be adapted for use in other conservation imaging studios. Inclusion of equipment and supplies in the manual is not an endorsement; in most cases similar materials may be substituted.

The manual is a step-by-step guide used by approximately 40 Conservation Division conservators, preservation specialists, and technicians with a wide range of digital image documentation skill levels and experiences. Created by an internal committee within the Conservation Division, the manual is based on protocols in The AIC Guide to Digital Photography and Conservation Documentation (ed. Jeffrey Warda, 2017, 3rd edition), workshops taught by Jiuan-Jiuan Chen to the Conservation Division in 2016 and 2017, training in conservation graduate programs, and advice from outside consultants. The manual abides by the AIC Code of Ethics and Guidelines for Practice.

The manual is divided into three parts:

The Primary Workflow provides instructions for setting up computer and software preferences, image capture using normal illumination and a digital SLR camera, addition of metadata, post-capture image processing, and archival printing.

The Secondary Workflow describes additional imaging modes using standard cameras, including: raking illumination, transmitted illumination, specular illumination, polarized illumination, UVA-induced visible fluorescence, and slide capture using a digital SLR camera; photomacrography using a stereomicroscope; and photomicrography using a compound polarized light microscope. Raking and specular illuminations record distortions in the surface planarity and topography of an object, while transmitted illumination emphasizes variations in the thickness of an object, revealing characteristics such as watermarks and repairs. Polarized illumination is used to reduce or eliminate surface reflections, while UV-induced visible fluorescence distinguishes and characterizes materials and markers of deterioration.

Two side-by-side images in comparison for conservation treatment

Mary Cassatt, Jeannette and her mother seated on a sofa, 1901, Prints and Photographs Division FP – XIX – C343, no. 177, before conservation treatment in normal illumination (left) and UVA-induced visible fluorescence (right), which captures the extent of staining in the margins of the paper support unseen to the naked eye. If left untreated, this type of staining can become visible over time.

Finally, the Multimodality Workflow describes imaging modes using a modified camera (a standard digital SLR camera with the IR-blocking filter removed), including: visible illumination, reflected infrared, visible-induced infrared luminescence, UVA-induced visible fluorescence, and reflected UVA photography; as well as false color infrared and false color ultraviolet image processing. All of these imaging modes help to distinguish and characterize materials used in collection items, such as colorants, inks, and paper sizing. Reflected ultraviolet photography specifically emphasizes surface coatings and adhesives, while reflected infrared photography can reveal underdrawings and pale or concealed inscriptions.

Multimodal images of a Japanese print (Utagawa Toyoharu, 1767-73, Ukie sakaicho fukiyacho kaomise yoshibai no zu, Prints and Photographs Division FP 2-JPD, no. 1967). From left: visible illumination, UVA-induced visible fluorescence, reflected UVA, visible-induced infrared luminescence, reflected infrared, false color infrared, false color ultraviolet.


Multimodal images of known Japanese printing ink colorant samples. Colorants in historical Japanese prints can be characterized and/or identified by comparing their multimodal responses to those of known colorants.

Both the combined manual and individual sections can be downloaded here.

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