January 2002 Volume 24 Number 1

Conference Review

The History and Treatment of Works in Iron Gall Ink

September 10-14, 2001.

An iron gall ink workshop was hosted by the Smithsonian Center for Materials Research and Education, Suitland, MD between September 10-14. Dr. Johan (Han) Neevel and Birgit Reissland of the Instiuut Collectie Nederland (ICN), were the principle speakers and instructors for the workshop. Their information was supplemented by eleven lecturers and additional demonstrations such as "simmering" technique by Julie Biggs and powdered ink by Elissa O'Loughlin.

The first day was organized as an introduction to the science, history, manufacture, and variety of iron gall, or metal gallotannate, inks. The second day held demonstrations and activities to identify and treat materials with this ink. A separate lecture day rounded out the workshop.

Research into the mechanism of cellulose and iron gall ink has been conducted at ICN during the past few years. Phytate solutions are the latest promising treatment method for iron gall ink. Phytates occur naturally in grains and help protect seeds. Phytate solutions interrupt the cycle of iron oxidation and acid-catalyzed hydrolyses at a site known as the Fenton reaction taking the more reactive iron (II) molecules and converting them into less reactive iron (III) molecules. As used in conservation treatments, residual phytate forms white crystals (an indication of the completely bound water in the system). A way to produce a non-aqueous phytate solution is also being investigated at ICN.

Phytates have been observed to quickly grow mold in solution. Scott Homolka, a graduate student at Buffalo State College, has done some research regarding the susceptibility of phytate-treated samples to grow mold. Using Aspergillus niger, the research indicated increased mold growth on phytate-treated samples that were incubated at very high relative humidity levels. However, additional research investigating different kinds of mold and exploring lower relative humidity levels needs to be done for a better understanding of the potential for this occurrence.

The message I got from the workshop is when treating iron gall ink, do all or nothing. Elmer Eusman's research indicates that humidification either in a cold chamber or with Gortex™ felt has moved inks detrimentally by introducing water which drives the acid-hydrolysis and iron-oxidation cycle. This is also true of water washing. If you are going to treat, do so thoroughly. Calcium carbonate solutions seem to work best, but are difficult to get into aqueous solution. Magnesium containing solutions (e.g. magnesium bi/carbonate) are believed to be detrimental to the ink, however the mechanism is not yet understood. Tests by many researchers have indicated the ink turns paler brown tones after treatment. Aqueous calcium hydroxide was found to be an inconsequential treatment for the ink, although helpful to many papers. "Simmering" (formerly known as "boiling") technique is being used in Europe. The method appears to effectively remove iron (II) ions, but there are questions regarding the effects of high temperature on removing the paper sizing and potential shrinkage of overall dimension. Combinations of these techniques, such as immersion in a preparatory ethanol bath, simmering, then calcium phytate followed by calcium carbonate wash baths are being tried. All methods mentioned here are still under investigation.