The 2020 Virtual Poster Session on Tuesday, July 21 featured nine authors presenting their research. Click on the title to read the corresponding abstracts before downloading.
The Effect of Various Aqueous Bathing Solutions
Careful tailoring of aqueous solutions for paper bathing has long been part of paper conservation. Previous research (Bogaard and Whitmore 2001; Hanson 1939) has revealed that calcium content within paper promotes better aging qualities (e.g. retention of strength and reduced yellowing with age), thus calcium has been used to enrich bathing solutions. However, the comparison of different bathing solutions and their quantifiable effect on the calcium content of paper has rarely been discussed. Therefore, answers were sought to the following questions: In aqueous paper bathing procedures, how much is the inherent calcium content of the paper affected? Does the use of chelators remove calcium from the paper? When paper is bathed with calcium-enriched water, is calcium successfully incorporated into the paper substrate?
A series of baths was designed to emulate common bathing, cleaning, and rinsing solutions. Atomic absorption spectroscopy (AAS) was used to quantify the calcium content of historical paper with inherent calcium content. Calcium content was measured before treatment, after one round of bathing (including chelators, DI water, pH adjusted water, and calcium-enriched water), and after a second round of rinse-bathing with a variety of calcium-enriched solutions.
The AAS results after the first round of bathing revealed that all of the solutions reduced the inherent calcium content significantly, including the calcium-enriched solution. Depending on which chelator is used and their respective pH and conductivity, additional calcium was also extracted. The second round of bathing revealed that the calcium-enriched solutions were unequal in terms of reintroduction of calcium back into the paper. Some of the paper samples were left with much less than their original inherent calcium content, while other solutions restored the content and imparted a calcium reserve.
Based on the results of this preliminary study, it appears that some of the common assumptions of aqueous treatment may warrant closer scrutiny. This study found that bathing solutions leached calcium out of paper, and the calcium-enriched solutions did not always reintroduce enough calcium back into the paper to return the content to its original level. Future studies could examine alternate methods of re-introducing calcium to paper and methods of adjusting chelators to spare calcium content. Ultimately, further study on a larger scale is necessary to fully understand the effect bathing solutions have on the calcium content of paper.
Bogaard, John, and Paul M. Whitmore. 2001. “Effects of Dilute Calcium Washing Treatments on Paper.” Journal of the American Institute for Conservation 40 (2): 105-123.
Hanson, Fred S. 1939. “Resistance of Paper to Natural Aging.” The Paper Industry and Paper World 20: 1157-1163.