Season Tse of CCI reported on collaborative research conducted with co-authors Maria Trojan-Bedynski and Doris St. Jacques. The research was designed to investigate treatment possibilities for an 18th-century Haggadah prayer book from the collections of Library and Archives Canada.
The Haggadah text is written on handmade, laid paper in iron gall ink with decoration and drawings in red and blue pigments and a green copper pigment. The green copper pigment was analyzed and identified as atacamite—not the verdigris they had expected. Over time, both the iron gall ink and the atacamite have contributed to significant deterioration of the paper.
The Haggadah was previously treated at the Library in 1987. At that time, breaks in the paper support were repaired with tissue and a carboxymethylcellulose adhesive. Initially, the treatment was to include treatment with magnesium bicarbonate applied on the suction table. Because feathering of pigments occurred during application, however, this treatment was halted, and the remaining leaves were instead deacidified with WeiT’o.
Although the 1987 treatment slowed ink corrosion, evidence of continued discoloration and breaks resulting from the iron gall ink and green copper pigment convinced conservators that the treatment was insufficient. Research was designed to determine if a non-aqueous antioxidant treatment could provide a safe and effective means to further slow deterioration of the Haggadah.
Test samples were created by applying iron gall ink, an iron-copper ink, atacamite, and verdigris to Whatman paper. All of the samples were pre-aged, then treated with WeiT’o and Bookkeeper alone and in combination with the antioxidants TBAB and EMIMBr.
Following treatment, half of the samples were heat-aged. All of the samples were then tested to identify any change in color, pH, and tensile strength.
Tse was not able to present all of the results in the allotted presentation time, but she reassured the audience that all details will be included in the paper submitted to the BPG Annual following the conference.
Tse first presented the results for the iron gall ink samples. The inks treated with WeiT’o appeared darker and more saturated, while the inks treated with Bookkeeper appeared lighter. Both WeiT’o and Bookkeeper raised the pH of the inks, but neither fully neutralized them. The pH did not fall after heat-aging. Deacidification did improve paper strength, but not enough to be considered sufficient for treatment. The antioxidant treatments did not contribute to an increase in paper strength.
The results of deacidification and antioxidant treatments differed for the atacamite samples. The two samples treated with a combination of an antioxidant and Bookkeeper (TBAB and then Bookkeeper, and EMIMBr and then Bookkeeper) showed the least color change of the pigment after heat-aging. Unlike the ink samples, for atacamite, deacidification did not improve paper strength, while the antioxidant treatment did improve paper strength.
For now, antioxidant treatment has not been undertaken for the Haggadah because Tse and her co-authors determined that neither of the tested antioxidants sufficiently benefitted the acidic iron gall ink. Tears and breaks in the manuscript were stabilized using a remoistenable Berlin tissue coated with gelatin and reactivated with a combination of ethanol and water.