AIC's 47th Annual Meeting

Titanium dioxide was the white pigment of the 20th century. Non-toxic, inexpensive, and with high covering power, it was everything that zinc and lead white pigments were not. Although synonymous with ‘modern art’ (roughly from the 1860s to the 1970s), close assessment of titanium dioxide can provide dating information because changes in manufacturing chemistry altered the compositions of available pigments in well-defined ways. The first titanium white pigment produced in the United States was the anatase form co-precipitated onto barium sulfate (1916). The anatase form co-precipitated onto calcium sulfate was introduced by 1925, and pure anatase itself was widely available by 1927. The rutile form, which has a higher refractive index and greater coloring power, was at first more difficult to manufacture, co-precipitated rutile pigments were introduced in 1941, and the pure rutile species in 1957. Anatase co-precipitates were reportedly phased out in the 1940s, while production of the rutile calcium sulfate co-precipitate continued until the 1970s. Accordingly, the crystal form of the titanium dioxide, which is easily and non- or minimally- destructively determined by Raman spectroscopy, provides some dating information. Determining whether the pigment is co-precipitated would allow more precise dating, but mere co-detection of barium or calcium sulfate with titanium dioxide is inconclusive: sulfates are commonly used fillers that might be mechanically added to titanium dioxide paint. Fortunately, some titanium dioxide pigments bear within them trace elements that can serve as markers for the source of the titanium ore and their method of manufacture. Recent technical studies on abstract expressionist paintings at the Museum of Fine Arts, Houston, the Menil Collection and the Metropolitan Museum of Art revealed a luminescence signature from titanium white paints whose pigment had been manufactured by co-precipitation with calcium or barium sulfate. We propose that trace neodymium, a rare earth element present in some ilmenite (FeTiO3) ores, can become trapped in the sulfate during co-precipitation, generating a luminescent marker characteristic of both the ore and the process. The luminescence is linked to a specific ilmenite source used in historic Titanox® pigments manufactured in the USA, permitting identification of the mineral source (similar to trace element analysis of obsidian, marble, or lapis lazuli). The signature is not present in pigments produced by more advanced chemistries, allowing identification of the manufacturing method. Facile Raman-based detection of this luminescence along with characteristic peaks of the sulfate and rutile or anatase can unambiguously identify the titanium white pigment and narrow its manufacture date range. A survey of 109 paintings of known provenance created between 1926 and 1986 reveals that the manufacture dates inferred from the luminescence are consistent with the production dates for these works. The luminescence frequently occurs in paintings by well-known artists including Franz Kline, Hans Hofmann, Barnett Newman, Andy Warhol, Robert Rauschenberg, and Jackson Pollock, artists whose works currently sell for millions of dollars and are targets for forgers as illustrated by the recent Knoedler Gallery scandal. This luminescence, therefore, represents a new, valuable tool for assessing the age and origin of an artwork.

For over 15 years, the conservation staff at the Isabella Stewart Gardner Museum has been carrying out treatments with a neodinium laser (Nd:YAG, 1064 nm), a tool increasingly recognized for its unique cleaning potential. More recently, an erbium laser cleaning system (Er:YAG, 2094 nm) was gifted to the Gardner’s conservation department with the express purpose of using it to learn more about its potential for cleaning works of art. Previous studies have shown that an Er:YAG laser works well in removing some types of aesthetically unappealing surface layers from art works in a more controlled and beneficial way than other cleaning techniques. Hydroxyl or OH-containing molecules absorb the erbium energy particularly well, or a solution containing a hydroxyl group, such as water or alcohol, can be added to a surface that does not already contain it. Energy absorption is restricted to the upper surface layer, and the unwanted material is broken down so that it can then be reduced or removed with gentle swabbing. The Gardner Museum staff and other local colleagues continue to test options for using this new tool and will review some successful Er:YAG cleaning applications on both objects and paintings. For instance, darkened and intractable layers, such as bronze powder (copper-alloy metal flake) paints and waxes that are often a challenge to remove from delicate gilt surfaces, appear to respond well to cleaning with the Er:YAG laser. Use of the Er:YAG laser can significantly reduce the amount of mechanical action required to clean these fragile surfaces. Similarly, darkened and oxidized varnish layers on a late 18th century oil painting that required strong solvent mixtures for reduction were targeted with the Er:YAG laser and then easily reduced with isopropanol. In addition to reducing abrasion of the paint film, there are also health benefits to working with less toxic solvents. The Gardner Conservators have also found that the Er:YAG laser can work in partnership with an Nd:YAG laser for certain applications. Nd:YAG lasers are commonly used to remove black pollution crusts from stone surfaces, however, a darkened appearance is often revealed below the crust. The Er:YAG laser system was extremely effective in reducing this appearance on an ancient marble sarcophagus after pollution crust removal with an Nd:YAG laser system. The Er:YAG laser was also employed for select cleaning in areas of pollution crusts that were either known or suspected to be obscuring original ancient pigment and gilding. In these areas the Nd:YAG laser might remove any original paint, however, the Er:YAG laser system could slowly reduce pollution crust in thin layers, exposing original pigment and gold in several locations. The Nd:YAG laser has become one of the essential tools in the Gardner conservation toolbox – like a scalpel or a swab. In these early stages of working with the Er:YAG laser, it appears possible to add another tool to that box, which has great potential for controlled and safe cleaning of artworks in the museum’s collection.

A new bonding system for the reinforcement of paintings made on textile supports will be presented. These are self-supporting, flexible meshes produced of a series of pure and well-established conservation adhesives. The main focus will be set on methylcellulose. Technically, the procedure involves positioning of the mesh in dry state, activation with controlled supply of moisture or solvents, and application of pressure to trigger the bonding. This approach enables an exceptionally precise application, thus minimizing the risks related to conventional use of liquid solutions, namely shrinking, stiffening and darkening of textiles. Furthermore, compared to hot-seal adhesives, methylcellulose meshes are particularly suitable for paintings that are sensitive to heat as no elevated temperatures are required for the activation. Adhesive meshes were developed particularly for the bonding of canvas, providing a regular, permeable adhesive pattern. Despite the lack of a carrier material, the meshes have a certain stiffness that allows to access detached layers through gaps or slits. Based on the successful application of sturgeon glue meshes (Konietzny, 2015), the method is now being complemented with meshes made from methylcellulose. This cellulose ether is among the most constant, ageing-resistant (Feller and Wilt, 1990) and, compared to popular synthetic polymers, sustainable adhesives used in conservation. Reliable adhesion has already been reported for canvas (Sindlinger-Maushardt and Petersen 2007, Bosshard-Van der Brüggen, 1972), wood (Döll, 1997) and leather (Gottsman, 2009) among other materials. The technique excels by its controllability and reversibility, when compared to other current practices. Unlike the common application in solution at low concentration, methylcellulose meshes are implemented as a solid that is activated with water or moisture, assuring the adhesive to discretely remain in the joint and create a mechanical bond without penetrating the textile. By varying the activation parameters, notably the amount of water, adhesion can be manipulated up to a remarkably high strength that was empirically found to be as strong as Beva® 371 films of 65 µm thickness. Meanwhile, the technique is being deployed by renowned institutions like the Swiss Institute for Art Research and the Swiss National Museum in Zurich (Switzerland) as well as the Doerner Institute in Munich (Germany). Detailed examination of adhesive mesh bonding and the development of meshes made from other materials such as acrylic adhesive to be used for water-sensitive works of art are the objectives of a current research project [Innosuisse No. 27510.1]. It is based at the Bern University of Applied Sciences (Switzerland), carried out in cooperation with APM Technica AG (Switzerland), the Dresden University of Fine Arts (Germany) and is financed by the Swiss Federal Innovation Agency. This paper aims at introducing methylcellulose meshes by presenting two case studies including strip lining and re-adhesion of a detached lining. Different activation strategies by water spray or a humidified capillary non-woven fabric will be demonstrated, both leading to convincing results. Moreover, perspectives of ongoing research and potential implementations in different fields of conservation will be addressed.

In an artwork, authenticity is the core quality that makes it valuable and unique. It is essential to the artwork’s identity, meaning and values, and remains the main driver of how the artwork will be experienced, understood, treated and displayed, or whether it will even be preserved at all. Evolving contemporary art conservation theory embraces J. Dewey’s aesthetics that the artwork is rooted in what the physical object and information does within human experience. This later echoed in C. Brandi’s idea that an artwork, in contrast to other physical objects, exists not only potentially, but actually when it is experienced, and is re-created every time by the beholder. As experience, it reaches beyond the present, back into the past authentic condition, and forward into future possible affordances. Consequently, the authentic condition may be fluid and different in different moments and contexts. In conservation decision making, identification of the authentic condition is a fundamental, but also very challenging task, where it is hard to reach a consensus among multiple stakeholders. Through the discursive lens, the paper explores methodological issues identifying the authenticity of condition in a group of weathered paintings by Edvard Munch associated with his “kill-or-cure remedy”, where the artist engaged the elements of nature as part of his technique that led to weathering and degradation of his paintings. With the focus on Munch’s paintings, the paper explores the issue of authenticity of condition in a context of contemporary art and draws parallels with Julian Schnabel’s weathered canvases that echo the “kill or cure remedy”, but also ephemeral art by Yoko Ono, Damian Hirst, Joseph Beys and others that embrace mutation of condition as part of their creative process. When treating ephemeral art, identification of the authentic condition(s) is critical for the treatment choices, and the decision-making process must encompass both material and non-material aspects of the artwork that may extend beyond the artwork materials and, perhaps even the original artist’s intent. Contemporary art conservation theory does not offer any straightforward methodology on how to deal with such situations. The paper emphasizes the importance of a holistic decision-making process to find a balance point where the artwork is continues to speak in its own voice, and not having that voice subjugated by evidence of the passage of time. While it may not be possible to reach a consensus among the stakeholders and avoid the dangers related to misinterpretation of the authenticity of condition, engagement in a broad discursive dialogue will greatly and significantly reduce these risks

This work, began by Serena Vella in 2008, focuses on The Tarot Garden, the famous sculpture park created, between 1979 and 2002, by the French and American artist Niki de Saint Phalle, on the Garavicchio Estate (Tuscany, Italy). It was inspired by the first 22 Tarot cards and two main parks: the old Park of the Monsters in Bomarzo and Parc Güell in Barcelona. The major sculptures are more than ten metres high and were intended to be inhabitable. They were built in concrete with an iron core and covered by tens of thousands of multicoloured tiles of mirror, glass and ceramic, all locally created by the artist and the ceramist at that time in charge. The material complexity of the sculptures, the environment in which they are immersed, and the weather conditions to which they are subjected, significantly affect the sculptures’ conditions, including the structures and their decorative tiles with chemical, physical, and biological degradation phenomena. The Garden is supported by the Fondazione “Il Giardino dei Tarocchi”, a private and non-profit organization instituted by the artist in 1997 with the aim of preserving the Garden. The sculptures are regularly kept under control by the Tarot Garden team, which is made up by a first group of people who assisted the artist in creating the sculptures and a second group of individuals who started working at the Garden more recently. To date, the daily maintenance procedures has involved the restoration of the structures and their covering tiles, which, when damaged, are usually replaced with identical tiles easily reproduced thanks to the original moulds conserved in the storehouse sited inside the Garden. This means that the artist planned for the substitution of the tiles. However, The Tarot Garden Foundation is now considering the chance to evaluate other possible solutions, directing the work to a more conservative approach, in order to reduce substitutions and to advance the preservation of the original materials. The project will have, not only the aim of proposing materials and techniques for conservation interventions, but, firstly of developing a planned and preventive conservation project with the goal of stopping or at least slowing down the degradation of the sculptures, keeping under control their condition thanks to a constant environmental monitoring of the Garden. The project will be supported by trained conservators and determined by the cooperation of experts working in academic research, in the fields of civil engineering and art conservation in order to: 1) not trigger further degradation phenomena with the use of non-proper products, 2) prolong the time between subsequent interventions, 3) reduce the substitutions of the original materials and ensure that the substitutions will not entirely replace in the long run the original parts realized in the ’80s, 4) replace the current maintenance procedures performed by the local team, guiding and directing them to a more conservative and methodical approach and to an interdisciplinary collaboration.

In response to climate change, cultural institutions are compelled to address their environmental impact by developing sustainable practices. Environmental sustainability goals for cultural institutions can foster innovative solutions for collections care that is independent from air conditioning and energy consumptive HVAC systems to include passive methods and simple technologies. In 2017, the Judd Foundation partnered with the Image Permanence Institute (IPI) to determine the viability of passive environmental conditioning methods for a number of its historic structures in Marfa, Texas. The primary goal of the project was to determine effective and minimally invasive passive methods to improve environmental conditions in each facility. The Judd Foundation preserves Donald Judd’s permanently installed living and working spaces, libraries, and archives in New York and Marfa. From the 1970s into the 1990s, Donald Judd acquired historic buildings in and around downtown Marfa and adapted these buildings as studio spaces and for the installation of art, architectural designs, and furniture. Judd’s original intent for installing works in existing spaces was integral in the design of this project. Marfa is a high desert climate and the historic Judd Foundation properties experience interior temperatures too hot during the day time for comfortable public access and for overall collections care. HVAC systems for the structures were rejected due to projected energy consumption, the number of sensitive historic structures in need, potential impact to Judd’s permanent installations, and understanding that mechanical solutions would be visually intrusive and difficult to maintain locally. Also, with the goal of sustainability, the Judd Foundation decided to consider other methods to improve the collection environments while working with, not against, the local climate. The IPI team inspected the properties and consulted with SCHAUM/SHIEH Architects to identify structures that were originally designed to use passive methods to condition the spaces and to determine if those systems were still viable. The team also examined alternative, unobtrusive measures that may be used in some of the structures. The diverse range of structures examined included former residences, office buildings, a former bank, and former military buildings. At every step, special attention to the buildings’ aesthetics was necessary so as to not interfere with Donald Judd’s original intent and the aesthetic he had created for each structure. A number of solutions were identified. A plan was created for each property utilizing a mix of passive measures and mechanical features to help improve the environmental conditions in the facilities. The measures included installing shades, creating passive air flow with vents and exhaust fans, and installing a localized air handling unit. In the end, the team of Judd Foundation, IPI, and SCHAUM/SHIEH Architects created a holistic plan to improve the environmental conditions of the buildings for the long-term preservation of the collection and the comfort of public tours that pass through without increasing energy consumption.