April 1, 2021: Start of the collaborative research project funded by the German Research Foundation Prediction of optical radiation-induced damage of white paper in cultural heritage preservation. The three-year project in collaboration with the Rathgen-Forschungslabor and the
Kupferstichkabinett at the Staatliche Museen zu Berlin focusses on the effect of light on the color changes experienced by historical and selected modern white paper and the significance of white paper substrates in microfading testing (MFT).
We had our first kick-off meeting on April 19, 2021, with partners from the Rathgen-Forschungslabor (RF) and the Kupferstichkabinett Berlin (KK), both at the Staatliche Museen zu Berlin, and the Hochschule für Bildende Künste Dresden (HfBK) and the Staatliche Akademie der Bildenden Künste Stuttgart (abk) (left to right, top to bottom): Thomas Prestel (HfBK), Ute Henniges (abk), Fabienne Meyer (KK), Irene Brückle (abk), Marie Kern (abk), Stefan Röhrs (RF), Dagmar Korbacher (KK), Georg J. Dietz (KK), Giulia Vannucci (RF); Mario Röhrle (abk, not shown).
We have been searching out old fabrics that would be suitable for the lab production of paper sheets mimicking historic handmade paper. Here is a set of unused linen and cotton fabrics dated from the first part of the 20th century and therefore free of optical brighteners.
The procedures of sheet production have undergone testing after selected fabrics were prepared by Gangolf Ulbricht, Berlin, to achieve a pulp quality appropriate for our research.
For our second paper sample set intended to mimic 19th to early 20th century industrial papers, we received two lots of sulfite cooked pulp from hardwood with significant lignin content (left) and low lignin content (right).
In August, we received our microfading tester (MFT) from Fotonowy, Krakow. Here you see Tomasz Łojewski (AGH University of Science and Technology, Krakow), who designed the instrument together with Fotonowy, demonstrating the use of this new-generation, user-friendly MFT. It features an LED (light emitting diode) illumination source. A tiny spot of intense light can be seen at the lower left in the process of being focused on a measuring spot on a piece of paper.
Pulps for the paper samples are doped with different ingredients. Here you see Marie Kern checking pulp in a beaker that has been prepared with calcium hydrogen carbonate to represent an alkaline reserve in the finished paper sample.
We carried out sheet formation in a customized hand papermaking wove mould. It that was equipped with a funnel inset into the deckle (made of Vivak® = PETG polyethylene terephthalate glycol). A polyester sheet over the mould surface prevented the measured fiber suspension that was poured in the funnel from premature drainage. Pulling out the polyester sheet induced sheet formation.
All the sets of paper samples were ready by the end of 2021: each folder contains about 15 sheets that make up a group. Depending on their fiber composition and ingredients added to the pulp, the color of the papers differ from each other. For example, sheets that were doped with iron ions show a yellowish tone. The red and blue markers indicate which sheets are to be sized with gelatin surface sizing, red indicating the addition of alum to the sizing.
We surface-sized the selected papers in a dilute gelatin solution, some of them also included alum as a historical additive. The setup you see here features a stainless-steel tray that holds the sizing solution. It rests in a tub with water that is heated with an immersion heater. The bath temperature is monitored with a thermometer. Presently, a sheet is immersed into the solution.
We preselected 3 red colorants from a selection of 16 commercial graphic arts types. For colorant application, we chose a porous pen with a broad nib that could be filled with the liquid colorant. The colorant was delivered through a square cut out of a polyester film (seen on the left) in the manner of stencil printing. This was tested different papers to check how their absorption properties influenced the colorant delivery.
The colorants chosen for their difference in light-fastness. The red squares of colorants applied to different papers are seen here after they had undergone accelerated light aging as part of the selection process. For one of the more light-sensitive colorants, one can see that the parts not protected with metal foil (flipped to the right side on the photo) are significantly faded.
We also included in our study chromophores that are typical for those found in aged paper. Three of the most common ones – dihydroxyacetophenone, dihydroxybenzoquinone, and dihydroxynaphthoquinone – feature a bright yellow, red, or blue colour in solution and were used to dope filter paper with the goal of observing their color change behaviour when exposed to light.
We spray-applied the dissolved chromophores individually and in a mixture on filter paper and air-dried the samples.
Preliminary result of chromophore light exposure in our Xenon light ageing chamber: a piece of metallized barrier material protected the center of the test panel from light (flipped open to the right). Color changes are evident – fading, but also darkening which includes yellowish color shifts – visible at the edges depending on the type of chromophore exposed.
Berlin, February 2022: Our project partner in Berlin received test panels with the samples (different white papers and red media) created at Stuttgart and mounted for framed display during art exhibitions at the Kupferstichkabinett, National Museums in Berlin
Berlin, February 2022: Above on view the current exhibition: Hell’s Black and Starlight. Dante’s Divine Comedy in Modern and Contemporary Art, 12.02.2022 to 08.05.2022.
Berlin, Kupferstichkabinett, February 2022: The illumination intensity on the test panel is measured by Fabienne Meyer.
Berlin, Kupferstichkabinett, since March 2022: In addition to the sample set that is repeatedly light-exposed in the museum’s exhibitions, one other set (see red arrow) is placed in the museum lobby for the duration of the research project. In the lobby, the sample set is exposed to a mixed lighting situation that includes natural day light from the windows and, at times, artificial light from the ceiling.
Berlin, Kupferstichkabinett and Rathgen-Forschungslabor, March 2022: The two Berlin teams have installed the data loggers that record the illumination intensity during the display. In this picture, Giulia Vannucci (left) from the Rathgen-Forschungslabor and Fabienne Meyer are seen with the sample set installed in the lobby of the Kupferstichkabinett (see also picture above).
Berlin, Kupferstichkabinett, since March 2022: A third sample set is exposed to a 100 lux artificial lighting situation for the duration of the research project.
Berlin, Kupferstichkabinett and Rathgen-Forschungslabor, early June 2022: The Stuttgart team and the Berlin teams collaborate on measuring the color of the sample set that was light-exposed for a first exhibition cycle at the Kupferstichkabinett Berlin (see above). Seen here are Giulia Vannucci (left) and Marie Kern (right) assisted by a graduate student intern from the Rathgen-Forschungslabor. They are working in one of the rooms of the conservation department at the Kupferstichkabinett.
Berlin, Kupferstichkabinett, June through October 2022: On view the exhibition „Holzschnitt
1400 bis heute”, 03.06.2022–11.09.2022,
August 2022: At Stuttgart, we started to work with our MFT instrument (Fotonovy), which features and LED light source (here, several blank papers are tested). The actual testing spot is much smaller than the spot seen during the instrument adjustment that precedes the actual measurement.
Marie Kern measuring a sample with the MFT that features an LED light source (Fotonovy). She works in a dark room with sparse illumination to avoid undesired light effects during the measurements. The red-colored reflections result from measuring one of the red colorant patches on a paper sample.
Marie Kern (State Academy Stuttgart) documenting the samples in VIS and UVA photography.
October 21, 2022: Giulia Vannucci (Rathgen-Forschungslabor, Staatliche Museen zu Berlin) speaking about results of MFT testing of selected paper samples during the international symposium that we hosted mid-term through our project, organized by Ute Henniges (State Academy Stuttgart).
Kupferstichkabinett, Berlin, November 2022. Current exhibition: Hannah-Höch-Preis 2022. Ruth Wolf-Rehfeldt. Wie eine Spinne im Netz. 02.11.2022 until 05.02.2023
The paper samples are placed in the aging chamber. They are sandwiched between filter papers and barrier films and stacked between tiles.
Three sets of 38 paper samples are laid out on the table for comparison after the first round of accelerated aging. Two sets were exposed to (dark) climate aging, and one of these two sets subsequently underwent light aging. The latter samples are now the darkest. The darkening is most distinctive in the lignin-containing paper samples that are placed close to the camera.
In February and March 2023, two paper conservation students from the Stuttgart State Academy of Art and Design were in Berlin to work on the research project during their spring break. This was also an occasion for members of the Berlin research group to meet and check on the samples displayed since February 2022 at the Kupferstichkabinett at the Staatliche Museen zu Berlin. In the left photo, Fabienne Meyer explains the light exposure of one set of framed paper samples displayed in the museum’s foyer, as seen on the back wall. In the right photo, the framed samples are inspected by the group in the current museum exhibition.
February–March 2023: The group also visited the study room of the Kupferstichkabinett to look at several artworks that feature previous light damage. The photo on the right shows how light damage changes the UV-induced luminescence. This can be seen in one corner of a print seen under the ultraviolet radiation of a handheld UVA-lamp (bluish oval).
February–March 2023: The Berlin group also visited the papermaking studio of Gangolf Ulbricht at the Kunstquartier Bethanien. The papermaker (seen left in the left photo) explained his work specializing in the production of artists’ and conservation papers (seen in the picture are Fabienne Meyer from the Kupferstichkabinett, Giulia Vannucci from the Rathgen Laboratory and Lina Wällstedt also from the Kupferstichkabinett). The group also inspected sets of paper samples produced for the project (seen in the right photo). On the far right is Stuttgart student Inga-Maria Teichert who worked at the papermaking studio in the production of sample papers.
Februry–March 2023: Also at the Kupferstichkabinett, the set of paper samples was documented using multispectral imaging with Multispektral from Xatra (available through Book2net).
February–March 2023: After the samples had been measured and documented, they were reframed and mounted in their third exhibition at the Kupferstichkabinett. This exhibit was entitled “Muse oder Macherin? Frauen in der italienischen Kunstwelt 1400 – 1800“, and ran March 8 to June 4, 2023. In the photo, Stuttgart paper conservation student Janine Nedela is measuring the light intensity across the frame already mounted in the exhibition space.
Kupferstichkabinett, Berlin, March 2023. Current exhibition: “Muse oder Macherin? Frauen in der italienischen Kunstwelt 1400 – 1800“. 08.03.2023 until 04.06.2023
May 2023: In this most recent meeting we discussed new results both from the comparison of different microfading testers, as well as results from measuring the paper sample sets aged both in light and dark-light cycles. In this photo, Giulia Vannucci shares results from the study of the MFT instruments on Blue Wool samples. The photos show (from the top): Giulia Vannucci, Irene Brückle, Ute Henniges, Stefan Röhrs, Fabienne Meyer, and Marie Kern.
July 2023: At Stuttgart, we ended the accelerated aging regime of the paper samples after two cycles were completed. Each cycle included climate aging followed by light aging. Here, we are inspecting the samples laid out on a table.
July 2023: A selection of paper samples was chosen for instrumental analysis. They were shipped to the Universität für Bodenkultur in Vienna, where they will undergo analysis of selected components under the direction of Antje Potthast. Of interest are the lignin content and the content in iron and calcium ions.
August 2023, project meeting in Berlin: The members of the research team assembled in Berlin to discuss their work and to plan an upcoming workshop in 2024. We spent one day at the Rathgen Forschungslabor where we also looked at the setup for the MFT device (from left to right: Stefan Röhrs, Marie Kern, Ute Henniges, Giulia Vannucci, Thomas Prestel, Irene Brückle).
August 2023, project meeting in Berlin, cont’d: We also visited the Kupferstichkabinett where we discussed a selection of light-damaged papers in artworks (from left to right: Ute Henniges, Marie Kern, Giulia Vannucci, Stefan Röhrs, Thomas Prestel, Fabienne Meyer). It was the first time that we had an analogue meeting with the entire group!
February 2024: One of our regular meetings in Zoom. Presently, we are planning a hands-on MFT workshop that will take place in March in Berlin, where we will also show the paper samples and discuss selected light-damaged artworks.
February 2024: In Stuttgart, we are preparing to archive the many sets of paper samples that were analyzed as part of the project. Ute Henniges shows students Jette Jöllenbeck and Anna Sophie Wagner the systematics of the sample collection.
February 2024: Student Lucie Voß prepares the samples for the upcoming workshop in Berlin. Every participant will receive a set of the samples we tested in our research for light sensitivity. These sets can be light-exposed in museums.
March 4, 2024: the exhibition “Die gerettete Moderne” (see below for further information) opened especially for a visit of the workshop participants. The exhibition featured works on paper that had been saved in 1937 by museum curator Willy Kruth from confiscation by the National Socialists. In view here is the light fading test panel. This is its fifth and last museum exhibition display within the duration of the project.
Die gerettete Moderne – Meisterwerke von Kirchner bis Picasso
02.02.2024 bis 21.04.2024
In 1937, numerous works of classical modern art were removed also from the Berlin Kupferstichkabinett as part of the National Socialist “Degenerate Art” campaign. The curator at the time, Willy Kurth, bravely saved hundreds of prints from imminent loss. Based on the 2023 publication “Die Aktion ‘Entartete Kunst’ 1937 im Berliner Kupferstichkabinett”, the exhibition showed selected works to show what escaped confiscation at the time.
March 5, 2024: The Berlin meeting also offered a final welcome opportunity to review some of the collected data
March 30, 2024: Official end of the three-year DFG project. The two Ph.D. candidates Giulia Vannucci and Marie Kern will continue completing their dissertations. The other team members will prepare manuscripts of the completed research for open access publication
May 28, 2024: Thomas Prestel presents his research and results of the project at the conservation colloquium at the Hochschule für Bildende Künste, Dresden.
June 12, 2024: The peer-reviewed journal Heritage Science has launched the Collection „Predicting the light-induced color change of white paper with MFT„. This is where we will submit the results of our collaborative research project.
June 2024: The paper samples handed out at the workshop in Berlin (March 4–5, 2024) are displayed in the conservation department in the Moderne Galerie, Saarlandmuseum in Saarbrücken. The samples are framed and exposed to light, with one half remaining covered and protected from light. This allows the color change of the paper samples to be observed over longer periods of time. Senior paper conservator Ingrid Schwarz guided student intern Marie Hauck from Stuttgart in mounting the samples.
