National Archives conservators: Caroline Whitley and Alana Lee

From the late Middle Ages until the early twentieth century, iron gall ink was the favoured writing and drawing ink in the western world. Most often used on paper or parchment (a writing material made from animal skin), it was indelible compared to earlier inks such as carbon, bistre and sepia. Its use ranged from everyday letter writing to the precious works of Michelangelo, Rembrandt, Bach, Hugo and van Gogh. Additionally, some very significant legal and political documents have been written with it.

As a prominent Australian example, Queen Victoria put her signature to the Royal Commission of Assent, Australia’s ‘birth certificate’ in 1900 at Windsor Castle. Queen Victoria presented this certificate to Australia’s Prime Minister Barton in 1900, along with the table, pen and inkwell she used in the official signing. Ownership of this suite of Federation objects passed from the Parliament of Australia to the National Archives of Australia in 1988. The monarch signed her name with iron gall ink, the same ink with which the document was written. Like many other historic artworks, illuminated manuscripts, maps, musical scores and official documents, the Royal Commission of Assent is endangered because the ink itself has the potential to deteriorate these significant works due to its destructive nature.

The Cultural Heritage Research Centre (University of Canberra) and the National Archives of Australia are carrying out research to better understand the damage that iron gall ink can cause. This research is co-funded by the Australian Research Council, Australian National University and three National collecting institutions; the National Museum of Australia, National Film and Sound Archive and Australian War Memorial.

Hundreds of historic recipes and various methods of preparation for iron gall ink exist. Originally, the ink was simply made in the home, monastery or artist’s studio. The basic ingredients were crushed oak galls (small spherical tree growths containing tannins), iron sulfate (naturally occurring in run-off from iron mines or extracted from rusty iron nails), gum arabic (resin from the Acacia tree) and a liquid (some that were used included water, beer, wine and urine). These ingredients were used in varying proportions and often contained varying contaminants (eg. trace amounts of copper). For added gloss or variation of colour and tone, other compounds or dyes were sometimes added, such as Brazilwood or pomegranate skins. Depending on local tradition, the ink solution was simply mixed and boiled, and sometimes left to ferment. The resulting ink was acidic because the chemical process that formed the black colour also produced sulfuric acid. By the nineteenth century, iron gall inks began to be scientifically formulated and sold commercially by ink manufacturers in efforts to standardise their quality.

Iron gall ink’s perceived permanence was one of the reasons why it was used to write legal documents and official government records. Despite this attribute, the ink has inherent problems that affect paper and parchment differently because paper is cellulose (plant) based and parchment protein (animal) based. Some iron gall inks have a corrosive nature over time, creating a brown halo around the ink lines and at worst effectively eating their way through the support, creating a lace-like effect. On parchment, flaking of the ink may also occur. Additionally, many of the inks have a tendency to change colour from black to brown over time, and often fade quite significantly.

Worldwide, many historic iron gall ink documents, manuscripts and artworks are in danger of severe deterioration, while others remain in excellent condition. This suggests that the particular ink compositions, the type of support used and the conditions in which the documents have been stored may contribute to their deterioration.

Our research in Canberra particularly focuses on the deterioration of the ink on parchment, the materials used almost exclusively for the valuable Federation documents held in the National Archives’ collection, including the Royal Commission of Assent.

After coming to Australia in 1900, the Royal Commission of Assent was on public display for decades at Parliament House under varying, unregulated environmental conditions that included natural and artificial lighting. When National Archives’ conservators thoroughly examined the document in 1988, they discovered it had suffered several forms of deterioration. Queen Victoria’s signature in the top left corner had faded to a pale brown colour. The body of the text had also faded and suffered some flaking of the ink.  Some of the text had been overwritten, and conservators detected the presence of several different inks.

Since 2001, the document has been on public display in the Federation Gallery at the National Archives of Australia in Canberra under strict preservation conditions, which include regulated temperature and humidity and low lighting levels from non-ultraviolet light sources.

Our research will help prevent any future light-induced fading of the Federation documents on display. Based on the lighting used in the Federation Gallery, we have constructed devices for a test situation to accelerate any effects of this lighting on laboratory prepared as well as historic samples of iron gall inks on parchment. The results will help us determine whether this current exhibition lighting could induce fading of various iron gall ink documents and if so, in what timeframe. We are also looking at ways to identify the inks and their composition, and are studying the damaging hydrolysis and oxidation processes they are believed to cause to their parchment supports. The research is currently due to conclude at the end of 2007, and we plan to publicise the full results and conclusions within the next couple of years. Further funding will be sought to continue the project.

This research plays an important role in the worldwide investigation of this enigmatic ink. In order to learn from each other’s research, we remain in close contact with European researchers who are studying the deterioration of iron gall ink on paper supports. We have presented interim results at both national and international conferences in both conservation and scientific fields. An understanding of the damage iron gall ink has the potential to cause is essential for the development of successful conservation treatments, which in turn will help us preserve the Royal Commission of Assent and other precious documents, manuscripts and artworks affected by this process.

A version of this report was originally published in Issue #32 of Memento (NB: PDF download), the magazine of the National Archives of Australia.