Master thesis abstracts 2021 / publication information

Lisa Behrens. Ink corrosion on parchment: investigation of different treatment strategies using aqueous solutions.

Ink corrosion on parchment is a phenomenon that, in contrast to its counterpart on paper, has so far been little researched. The same applies to the possibilities of conservation treatment. In order to gain clues for conservation treatment and also suggestions for possible further research, five different water-based treatment methods were investigated: calcium phytate (adjusted to pH 5.3 or 3.0), type B gelatine, phytic acid and calcium phytate in combination with gelatine. These selected substances were tested in appropriate treatments on 70 samples prepared by the researchers themselves, consisting of velour calf parchment inscribed with a laboratory-prepared iron gall ink, and on 36 samples from an early modern document that had been inscribed with an ink proven to contain iron. The treated samples were analysed by UV/VIS spectroscopy, the bathophenanthroline test and ATR-FTIR spectroscopy. The shrinkage temperature of individual samples was determined to supplement the results. None of the tested treatment methods reliably inhibited ink corrosion. Apart from a moisture-catalysed acceleration of degradation reactions, no adverse effects were observed. There was evidence to suggest that oxidation is more important than hydrolysis in ink erosion on parchment.

Franziska Leidig. Cold storage of front- and back-mounted photographic art: investigation on the effect on composite mounting materials.

In order to investigate the effect of cold storage on the material compound of face- and back-mounted photographs, six large-format samples and one damaged original artwork were exposed to alternating cold and warm temperatures. The temperature inside the cold storage was set at 8°C, while the room temperature outside fluctuated depending on the prevailing weather conditions. In a 24-hour rotation over five weeks, the test materials were exposed to strong and rapid fluctuations in order to assess possible effects on the chemical and physical stability of the composite materials. The samples were examined daily for changes and the surface temperature, and the expansion behavior of the acrylic glass and its backing were measured. Taking into account the material-specific thermal conductivity, it was estimated how the temperature spreads within the composite to understand prevailing stress conditions. Due to the high stress, also resulting from test duration and temperature fluctuations, irreversible deformation occurred. Further, localized stains between the acrylic glass and the photograph emerged, possibly caused by chemical degradation processes within the photographic emulsion. In addition, incipient delamination was observed on the pre-damaged original artwork. An unavoidable exceeding of the dew point temperature resulted in condensation and led to extreme soiling of the acrylic glass surfaces. Overall, the findings of this work underline the importance of stable climatic conditions for the storage of face- and back-mounted photographs.

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