Evaluation of novel cleaning systems on mock-ups of unvarnished oil paint and chalk-glue ground within the Munch Aula Paintings Project

Abstract

Low-risk removal of embedded surface soiling on delicate heritage objects can require novel alternatives to traditional cleaning systems. Edvard Munch’s monumental Aula paintings (1911–16) have a long history of exposure to atmospheric pollution and cleaning campaigns that have compromised the appearance and the condition of these important artworks. Soiling removal from porous and water-sensitive, unvarnished oil paintings continues to be a major conservation challenge. This paper presents the approach and results of research into the effect and efficiency of three novel systems used for soiling removal: soft particle blasting, CO2-snow blasting, and Nanorestore Gel® Dry and Peggy series hydrogels. Cleaning tests were performed on accelerated-aged and artificially soiled mock-ups consisting of unvarnished oil paint and chalk-glue grounds. Visual and analytical assessment (magnification using a light microscope and scanning electron microscope, as well as colour- and gloss measurement) was carried out before and after mock-up cleaning tests and the results were compared to those obtained using the dry polyurethane sponges employed in the most recent Aula surface cleaning campaign (2009–11). Although the results varied, the Nanorestore Gel® series proved promising with respect to improved soiling removal efficiency, and reduced pigment loss for the water-sensitive surfaces evaluated, compared to dry sponges.

A hypothesis on the initial film formation by deposition from the indoor air on clean filter samples and its relevance for unvarnished oil paintings on canvas

“…As the soiling layer increased, it would also undergo other physicochemical changes -for example becoming harder due to further oxidation, cross-linking and bonding, cementation, and reaction with surface substrates and so on -that would further deteriorate the artwork's surfaces. The result of these processes in the long term has been the variably tacky, acidic, and hydrophilic soiling layers that have been observed to be so di cult to clean from Munch's Aula paintings (Figure 7) 44 . Clearly, more investigations are needed to understand such surface lm development.…”

Minimally Invasive Liquid Microjunction Sampling to Identify Dye on a 17th Century Spanish Illuminated Manuscript

“…However, solvent exposure can generate tidelines (discoloring lines indicative of solvent damage). To avoid adverse surface reactions, optimization is required …”

“…To avoid adverse surface reactions, optimization is required. 11 In this work, colorants painted on a 17th century Spanish illuminated manuscript were studied. Previous XRF analyses had identified inorganic pigments throughout the manuscript illuminations.…”

Non-proximate Sampling and Photoionization for Damage-Free Mass Spectrometric Analysis of Intact Native American Baskets

“…Analyte material cannot be retrieved by bulk vaporization that would remove large amounts of substrate, but neither may a probe or laser visibly pit, discolor, melt, or burn the surface. Water or other solvent exposure can also produce adverse reactions and surface effects in the short- and long-term . Direct analysis of the most sensitive objects requires not only a minimally invasive desorption approach but that the whole item be positioned far from the MS, where it can only be accessed by non-proximate sampling …”

“…Water or other solvent exposure can also produce adverse reactions and surface effects in the short-and long-term. 4 Direct analysis of the most sensitive objects requires not only a minimally invasive desorption approach but that the whole item be positioned far from the MS, where it can only be accessed by non-proximate sampling. 5 There are four models for real time, non-proximate sampling and transmission to a MS: two that transport analyte as ions, and two that transport neutral material.…”