By SYLVIA ALBRO and JULIE BIGGS
The focus on new research and methodologies for iron-gall ink treatment at the Library of Congress has resulted in an array of practical tools for use by conservators in libraries, archives and museums worldwide.
Iron-gall ink was the primary writing ink used from 12th through the 19th centuries in the Western world. Popular with artists, architects and mapmakers, iron-gall ink is found in abundance in paper-based collections at the Library of Congress.
The Manuscript Division holds many seminal documents by the Founding Fathers written in iron-gall ink and it is well represented in other collections, such as maps in the Geography and Map Division; art and architectural drawings in the Prints and Photographs Division; scores by famous composers in the Music Division; and ancient manuscripts in the African and Middle-Eastern Division. Some of the documents are featured in the Library’s new exhibition, “Creating the United States.” (See story on page 95.)
By the end of 2007, many important artifacts received treatment including the following items that will be displayed in the Library’s exhibit spaces in the Jefferson Building and the new Capitol Visitors Center:
- George Washington’s annotated draft of the U.S. Constitution
- Benjamin Franklin’s copy of the First Continental Congress Petition to the King
- Two copies of William S. Johnson’s annotated drafts of the U.S. Constitution
- Thomas Jefferson’s copy of Franklin’s Articles of Confederation
- Thomas Jefferson’s 1801 Inaugural Address
Recipe for Disaster
Many different recipes for iron-gall ink are recorded in historical texts; the most common ones had four main ingredients: oak-tree galls, iron sulfate, water, and gum arabic. The galls were mixed with water to release tannins, which reacted with iron sulfate to form a dark-colored solution.
Gum arabic was then added to ease the flow of ink in quill pens and later, in metal-nib pens. The relative proportions of these ingredients, along with other additives, determined the ink’s stability over time. Often the amount of iron added to the solution was in excess of what was needed for a balanced chemical formula, resulting in ink corrosion, a degradation process that involves two chemical reactions: iron-catalyzed oxidation and acid hydrolysis.
Paper artifacts affected by ink corrosion are acidic, discolored, brittle, and sometimes even riddled with holes. Iron-gall ink corrosion is seen in huge numbers of historical artifacts in museums, archives and libraries around the world and corroded artifacts are difficult to access without further damage or potential loss.
Beginning in the late 19th century, various treatments were utilized to combat ink corrosion, such as lining the item with paper or silk cloth, or lamination with cellulose acetate. Although well-intended, they were largely methods to reinforce the damaged paper but did not address the chemical corrosion of ink, and often resulted in treated items becoming even more fragile in the long term. Later attempts to treat the ink focused on reducing acidity but did not deal with the bigger problem of iron-catalyzed oxidation.
The Library of Congress’s Conservation Division has spent the last six years investigating condition problems associated with iron-gall ink-inscribed artifacts. The work was prompted by the emergence of exciting new research results from Europe, the need to evaluate this new research, update conservation procedures at the Library, and where appropriate, adopt or develop new tools and innovative treatments for iron-gall ink on paper.
Within the last decade, several international groups have studied iron-gall ink corrosion and methods to treat it. Researchers from the Netherlands Institute for Cultural Heritage (ICN), in particular, developed a spot test for iron that aids in assessing the stability of historical iron-gall ink, and introduced a breakthrough chemical treatment for ink corrosion that combats both oxidation and acidity in ink-inscribed paper.
A significant technological advance was the commercial introduction of multi-spectral imaging systems, one of which the Conservation Division purchased in 2005. These systems have different wave bands on the light spectrum that can be used to identify iron-gall ink non-destructively, to determine the condition of historical ink, to evaluate treatment, and to enhance faded and illegible texts.
In 2002, the Conservation Division invited the ICN researchers to present their work at the Library, which shortly thereafter initiated its own research project by establishing the Iron-Gall-Ink-Corrosion (IGIC) Group. This group, comprised of staff conservators and a scientist from the Preservation Research and Testing Division, tested commonly used Conservation Division treatment protocols alongside the recently developed European protocols. While awaiting the conclusions of the research, conservators delayed the treatment of many important iron-gall ink-inscribed artifacts. The first phase of the project was completed in mid-2005 and the Group approved a variety of successful treatment options that could be used for typical Library of Congress artifacts, depending on the chemical makeup of the collection item and its physical condition.
The Protocols for Iron-gall Ink Treatment (PIT) Group was formed in 2005 to develop a package of examination and treatment guidelines for staff to use on iron-gall ink-inscribed artifacts. The group studied the research results, proposed different methodologies that conservation staff members were invited to test and evaluate, formulated decision-making flowcharts called “Treatment Trees,” and provided written instructions and training for staff on approved procedures. In this way a unified approach to the preservation of iron-gall ink artifacts in Library of Congress collections was adopted and consistent practices are now being followed and documented for the historical treatment record.
Library of Congress conservators have successfully presented their work at American Institute for Conservation conferences in 2004, 2005, 2006, the Institute of Conservation conference in Edinburgh, Scotland, in 2007, and the American Institute for Conservation conference in Denver in April 2008.
As the Conservation Division’s iron-gall ink initiative progresses, it has ongoing relevance not just for the Library’s collections but also for conservators who are responsible for historical iron-gall ink collections internationally.
Sylvia Albro and Julie Biggs are senior paper conservators in the Conservation Division.