Justine Bolle. Study on the color changes of cyanotypes during and after anoxic treatments.

The extent of fading of cyanotypes under anoxic pest control measures was investigated with regard to either temporary or permanent color loss even after returning to an oxygenated environment. Specially produced and selected historical cyanotypes were treated anoxically for four weeks. After anoxic treatment under controlled conditions, the color values of the cyanotypes regenerated to a degree comparable to the naturally occurring color difference of the unaged reference samples. From this it can be concluded that short-term anoxic treatment of cyanotypes is possible without permanent color change. However, anoxic treatments should generally be avoided for pre-damaged cyanotypes in order to avoid any risk of color changes. Dark storage under oxic conditions can generally restore the color values to the previous state.

Presentation information: Justine Bolle and Bill Landsberger. Cyanotypes and anoxia: Investigations on the color changes of cyanotypes during and after anoxic treatment. talk at the conference: Integrated Pest Management for Cultural Heritage 18–20 September 2024, Humboldt Forum Berlin, Germany, Sept. 19 (https://ipm2024.org/program/).

Esther Hannemann. Application possibilities and application techniques of benzotriazole and tetrabutylammonium bromide on copper pitting damaged paper.

Application possibilities of the complexing agent benzotriazole (BTA) and the antioxidant tetrabutylammonium bromide (TBAB) on copper corrosion-damaged papers (gelatine-sized and unsized) were investigated. Chemical and mechanical stabilization was tested with a mixture of Klucel^® G and the treatment reagent. Also, Nanorestore^® gel as a poultice for use with BTA was tested. The BTA treatment proved to be effective with sized and even more so with unsized sample papers. In the combined mechanical and chemical stabilization, admixtures of BTA (1, 3, and 5%) and an admixture of TBAB (1%) produced good results. Treatment with a chemically modified remoistenable tissue proved to be more effective than a freshly applied, chemically modified adhesive. The Nanorestore^® Gel loaded with a BTA-ethanol solution gave moderately acceptable results. Apart from a yellowing of lead white, BTA showed no negative effects on ten color pigments that were both exposed to light and thermally aged after BTA treatment. In summary, it can be said that the various application options, especially BTA, but also TBAB, showed good results in the treatment of copper corrosion. BTA has some advantages due to its easy application and good effect, but also disadvantages such as yellowing and crystallization under certain environmental conditions. Remoistenable tissues with the chemically modified Klucel^® G showed promising results.

Philipp Mattausch. Structure from Motion as a tool for documenting the condition of art on paper.

The photogrammetric Structure from Motion method was considered as a tool for the virtual representation of paper topographies and tested for its suitability for the visualization of deformations on paper artworks. Three paper samples with different surface textures were tested. This revealed a strong dependence of the model quality on the structure and color of the object. The model creation was based on the workflows for generating terrain models using aerial photographs. To create the comparative models, three image sets were processed in five different workflows, thus testing the range of factors influencing the quality of the resulting models. The method proved to be suitable for mapping surface models with an accuracy of less than one mm. The surface comparison revealed deviations of up to 0.3 mm, particularly at the edges of the sheets. The reproducibility and deviations from a reference model created with a strip light scanner compared favorably. Models photographed with wide-angle lenses showed a smaller deviation than those photographed with longer focal lengths. By using the method to document the movement of one of the sample papers as an example, the deformation of the paper could be visualized using a surface comparison.

Miyon Schultka. Mounting of works of art on paper. Effects of adhesive selection, adhesive application and climate fluctuations on load-bearing capacity and deformation behavior. 

The influence of different adhesives and application techniques on the deformation behavior and shear strength of hinges on paper was investigated. The shear strength of bonded joints was tested in a room climate using a tensile testing machine until breakage occurred and at increased relative humidity (70–90% RH) in a climate chamber with weight-loaded hanging (140 g). The deformation of the bonded joints was evaluated after exposure in a fluctuating climate (5 days cyclic 40% and 60% RH) via photographic documentation. Three different sample papers (gelatine-sized rag paper, heavily calendered machine paper, PE-coated photographic paper) were hinged with Japanese paper on which adhesive (heat-activated: Lascaux© HV 498; liquid: Klucel™ G in ethanol, 2.5% and 4% methylcellulose, 1:5 wheat starch:water, 20 % Aquazol^® 500) was applied either over the entire surface, as a microdot with a stamp or Velcro tape (hook tape) or as a narrow line. The non-aqueous adhesives produced less deformation than the aqueous adhesives, but the use of microdot significantly reduced the deformation of the aqueous adhesives. Bonds with methylcellulose were more resilient than bonds with wheat starch paste, even after several days of exposure at 90% RH. The application method showed an increasing load-bearing capacity of hook tape → stamp → line → full-surface. Overall, it was found that the microdot stamp can withstand a high load that is sufficient for most standard mounts.