The following is a post by Cassandra Marando, the 2026 Librarian-in-Residence for the Preservation Directorate.
As the Librarian-in-Residence for Preservation, I learn something new every day about preservation techniques at the Library of Congress. I’ve had the opportunity to participate in many facets of Preservation; one section I work closely with is GCCS, or General Collections Conservation. While not a conservator myself, I’ve learned so much about the conservation techniques and processes that we use to ensure our collections are around for years to come.
It was in a conversation with my colleague, Preservation Outreach Librarian Jon Sweitzer-Lamme, that I first learned of the Library’s manuscript marking ink. I was so intrigued by the ink I immediately began to research it. Library staff often meet with other cultural institutions to exchange ideas on preserving and protecting books, and the marking ink came from one such collaboration.
In March 1983, the Library published a Preservation Leaflet from the National Preservation Program Office on manuscript marking. Manuscript marking, or institutional ownership marking, is a preventative measure used by institutions to mark ownership of items to discourage theft. There are multiple ways to mark items, including embossing, punching (as one would do to a ticket), perforating (like punching, but resulting in a small symbol made up of tiny holes rather than a large, single hole), and stamping ink on or in an item. While all of these methods are available, ink stamps do the least amount of damage to collection items.
In a 1976 draft of the 1983 leaflet, the Library first identified a need for a unique, indelible ink formula that was pH-neutral and permanent. Since an ink of this caliber was not commercially available yet, the Library partnered with the Government Printing Office (GPO) to create an ink for public use that fit these parameters. The ink, which we still use today, comes in four colors: black, blue, brown, and red. It cannot be removed with water or other solvents, and it does not fade. According to a post on a conservation email list web archive made by former Library of Congress Preservation Research and Testing Division Chief Chandru J. Shahani, the ink is difficult to remove because the particle size of the pigments “is so small that these pigments penetrate into the fiber structure of paper.”. This innovation in marking ink has helped libraries across the world safeguard their collections using a permanent, paper-safe method.
Currently, the Library is the holding institution for this ink. We provide bottles of it both internally to our staff and globally to any collecting institutions who send in requests. Organizations may submit a request for a, 65mL bottle of black, blue, or brown ink through Ask A Librarian. Detailed use instructions and further information about the ink can be found on the Library’s website.
When we think of libraries, we often imagine reference desks and vast shelves filled with books. While the more services we offer are incredibly valuable, my experience as the Librarian-in-Residence in Preservation has shown me the behind-the-scenes solutions libraries can offer to even the most niche problems. The indelible manuscript marking ink is a library service that I’d never known about before working here. As I am finishing up my residency, I continue to be awed by how much my definition of a library has expanded since I began. Something as small as a 65mL bottle of ink can significantly increase the safety of a collection for years, and it is an excellent example of how innovations by libraries can address larger issues. I hope that learning about the ink has made as much of a mark on you as it has on me.
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Sources:
Library of Congress, Marking Paper Manuscripts, Preservation Leaflet Series (National Preservation Program Office: 1983).
Chandru Shahani, “Library of Congress Manuscript Marking Ink,” Abbey Newsletter 20, no. 2 (Jun 1996): https://cool.culturalheritage.org/byorg/abbey/an/an20/an20-2/an20-210.html.