AIC's 53rd Annual Meeting

In this session, members of the core group of the AIC Ethics Core Documents Review Task Force will present the process followed to revise the AIC Code of Ethics, Guidelines for Practice, and Commentaries, and will host a discussion on this process. The core group was initially tasked with identifying areas in the core ethics documents that needed updating and forming subgroups to address these areas. Presenters will explain how we identified the subjects for updates, selected the subgroup topics, and chose subgroup members. The presentation will detail how subgroups approached their revisions, how feedback from the subgroups was incorporated into the first draft of the new AIC ethics core documents, and the subsequent process of gathering feedback from AIC membership. The session will consist of a presentation and ample time for questions and discussion.

This event is free and open to all attendees

The corrosion of historic organ pipes continues to be a major problem for older historic organs in Europe. This is particularly true in the pipe feet of the larger bass pipes which are made primarily of lead. Corrosion in the pipe foot reduces the load-carrying capacity of the pipes, and makes them more difficult, if not, impossible to tune as corrosion eats away at the pipe wall and eventually breaks through. A number of recent major research projects including the EU COLLAPSE project and a project in Bremen, Germany indicate that the cause is corrosion of lead by acetic and formic acids emitted from the wooden windchest. Several measures have been suggested for dealing with the problem including neutralizing or removing residual acid in the corrosion product, coating the insides of the pipe feet, or replacing the feet with lead-tin alloys. 

This research has been primarily chemical in nature. While it provides evidence for the cause of corrosion, the proposed measures have a number of logistical and conservation ethics problems. The production of the acids is continuous, which means that pipes have to be treated regularly with some kind of aggressive solution. Coatings must be regularly maintained and replaced. Given that the affected pipes are usually the large bass pipes in a complex organ structure, such treatments would be a difficult operation to carry out regularly. Furthermore, the proposed measures only treat the symptoms and not the source of the problem, the acid emission into the pipes. 

It was noted in the previously mentioned projects that corrosion tended to be worse in organs which were not played as often, and in silent pipes. This led to a multidisciplinary pilot study conducted by the Cultural Heritage Agency of the Netherlands (RCE) to investigate the possibility of venting the pipes when the organs are not played. A team including an organ expert, a Dutch organ builder, chemists and fluid mechanics experts is studying the airflow through pipes as they are played, to see if that correlates with the corrosion in the pipe feet. Three-dimensional (3D) computer modelling and high-speed smoke visualization techniques are being used to determine the airflow within a transparent organ pipe, and locate eventual “dead” zones where corrosive gas concentrations may be higher. Endoscopic techniques are being used to determine the location of the corrosion in pipe feet. A sensor is being developed to measure the acid concentrations in the air in pipe feet.

The results of the fluid mechanics studies and initial endoscopic work indicate that corrosion correlates with dead air zones in the pipe foot. Venting the pipes is possible, and would be best accomplished by reversing the air flow in the pipe, that is, in the opposite direction to playing. Further work is planned to determine how often venting is required, and the most efficient way of doing this using the existing blower, as well as dealing with the fact that the organ will be continuously producing tones while being vented.

Research into the Deathwatch Beetle infestation on HMS Victory led to a unique collaboration between The National Museum of the Royal Navy (NMRN), Cranfield University and The Zoological Society of London (ZSL): London Zoo. Deathwatch beetles are woodboring beetles that are pests to historic timber structures whose lifecycles can span anywhere between 1-13 years. Historic investigations into Deathwatch beetles made use of live cultures of the beetles for observation and experimentation. However, the cultures were never maintained beyond the course of each research period, much to the detriment of our understanding of the species.

A PhD research project was jointly funded by NMRN and Cranfield University to enhance understanding of the Deathwatch Beetle infestation on HMS Victory and explore methods of communicating complex conservation information to the public. During investigations into non-invasive methods of larval detection, it became clear that a live culture for study was sorely needed. There seemed little point, however, to starting a culture, only to have it die out once the research was concluded. The main issue is that the culture needs care and facilities to ensure it is maintained and monitored. Enter London Zoo.

London Zoo is equipped to maintain a culture long-term, and it fits within the normal remit and activities. The presence of specialist knowledge for the establishment and long-term development of the culture is essential. Having the culture in a central location with suitable resources and a vested interest in the long-term survival will enable the future research into Deathwatch Beetle activity and behaviour, but it can also serve as a means of public engagement with a wider audience. Remarkably little is known about the Deathwatch beetle, and knowledge gained from the culture would be useful for NMRN, but also other sites dealing with Deathwatch beetle infestations. Research and investigations could be conducted by students of Cranfield, strengthening existing, and establishing new, research ties. Displaying the culture, with explanations, to the public will bring heritage science research and HMS Victory to the attention of a wider audience that would not usually come across it.

For the Zoo, the use of a wood-boring beetle notorious for its cryptid nature to develop non-invasive means of detection, means that techniques and methods can be investigated and tested on a non-threatened species before being used to detect endangered species, like the Fregate Beetle. Wildlife and heritage conservation, and the science and research behind them, can greatly benefit each other.

Lead and lead contaminated materials can be a danger in art. It can be obvious or hidden, for example: lead-containing primers, pigments, sculpture substrates, corrosion products, pigments, or art that contains contaminated synthetics. Identifying lead-containing materials can significantly change the treatment strategy, require additional safety precautions, and increase costs. However, even with the commercial availability of highly sensitive spot testing kits, determining if the artwork poses a “real” risk is not a straightforward process. Conservators at Monumenta and MoMA recently found themselves in a confusing world of false positives, opaque and uncooperative technicians at testing laboratories, and misleading thresholds. It suddenly became hard to answer the simple question “does the sculpture contain an unsafe level of lead?” using readily available testing materials.

Lead spot-testing kits available for home use range widely in precision, accuracy, and sensitivity, and are marketed for a variety of use cases. Scant comprehensive research available on the efficacy and suitability of commercially available lead spot-testing kits for conservation purposes further exacerbates the challenge of parsing out the differences between tests, making it difficult for conservators to make informed testing decisions. Further uncertainty follows because many laboratory test results offer only "presence or absence" reporting; the identification of lead does not necessarily indicate unsafe levels of lead, only that lead exists in the sample. Additionally, Federal and State standards for the total amount of unsafe lead in parts per million are inconsistent and not well delineated compared to contamination from the environment or another source. Commercial environmental testing solutions also do not provide the interpretation of test results owing to liability concerns.

In response to this need for a reliable lead-testing practice, Conservators aim to develop a lead-testing protocol that includes both interpretation of in-the-field spot testing followed by comprehensive (qualitative) analytical testing using environmental laboratories all to ascertain a creditable risk. This work includes evaluating commercially available spot testing kits for their usefulness, surveying state and federal thresholds for lead-containing coatings, cultivating relationships with toxicologists, and developing strategies to communicate with environmental testing laboratories that are reluctant to interpret data for liability reasons. A summary of research to date will be presented, which represents only the beginning of much-needed research on this crucially important safety topic.

Paper conservators working with different concentrations of agarose gels have observed that stain removal efficacy increases as the gelator concentration is increased. Although the exact process(es) contributing to this increase in efficacy have not been studied previously, many physical phenomena are thought to play a role, including diffusion and capillarity processes involved in the transport of solvent and solubilized components to and from a substrate placed into contact with a gel. We propose that the process of adsorption plays an important role in the sequestration of water-soluble products once they have migrated into the gel. The adsorption of solubilized components by the gel network essentially purifies the bulk solvent in the gel, increasing the uptake of more material and preventing redeposition. 

Adsorption measurements of solid agarose indicate that it could remove 90% of crystal violet (hexamethyl pararosaniline chloride, C25N3H30Cl) from an aqueous solution rapidly. Even when engaged in a gel network, agarose is capable of functioning as an adsorbent. Critically, a gelator can do more than act as a vehicle to deliver solvent: it can also trap solubilized components via adsorption onto its polymer chains. By adding a range of additional adsorbents, including microcrystalline cellulose powder and silica gel (200400 mesh), at 1 wt% into agarose gels, we have shown we can increase the adsorption rate and total cleaning capacity of these systems. One consequence is we can reduce the amount of gelator required for a treatment.

If the mechanisms at work within gels are better understood, it may be possible to design systems that amplify the effects of stain removal treatments while reducing the need for expensive and/or unsustainable materials. Agarose, a component of the algal extract agar, is costly due to the purification process involved in isolating the polymer and the limited availability of the algae from which it is derived.[1] However, agarose is often preferred for gel treatment of paper due to its minimal deposition of residue and the good aging properties of those potential residues.[2] This research offers an approach to decrease the quantities of this important resource needed to carry out a conservation treatment. The applicability of adsorbent-bulked agarose gels in hands-on conservation practice is being tested, and the effectiveness of specific adsorbents for certain applications is being investigated. Through the close collaboration between scientist and conservator, conservation practice informs scientific experimentation, and analytical results can impact treatment methodologies.

[1] Santos, R., Melo, R.A. Global shortage of technical agars: back to basics (resource management). J Appl Phycol 30, 2463–2473 (2018). https://doi.org/10.1007/s10811-018-1425-2

[2] Warda, J., Brückle, I., Bezúr, A., & Kushel, D. (2007). Analysis of Agarose, Carbopol, and Laponite Gel Poultices in Paper Conservation. Journal of the American Institute for Conservation, 46(3), 263–279. https://doi.org/10.1179/019713607806112260

In recent decades, conservators and conservation scientists have proposed additions and refinements to the conservation cleaning toolkit, drawing inspiration from allied fields and leveraging expertise from industrial chemists and soft matter scientists. As a result, the field has seen continued progress toward options with improved control and specificity while also favoring materials and techniques that are more sustainable and safer for the practitioner and the environment.

Inspired by conservators’ creative adaptations of rigid physical hydrogels and the working properties of chemical hydrogels adopted by the field in recent years, this paper describes the development of physical hydrogels that are thermoreversible, optically clear, cohesive, flexible, and conformable with surprising elasticity and gel strength. Drawing from food science, haute cuisine, and traditional foodways, the shared formulations are based on the synergistic binding of xanthan gum and konjac glucomannans modified with a second network of agar or agarose. These versatile, cost-effective gels are simple to produce and are compatible with typical aqueous preparations used in conservation cleaning. Additionally, these hydrogels provide options for delivery of small proportions of organic solvents and microemulsions capable of swelling and removing tenacious coatings and overpaints with minimal mechanical action. Analogous formulations substituting other glucomannans or galactomannans and selecting agar instead of agarose offer flexible decision-making favoring economic and environmental sustainability by sourcing materials native to many regions around the globe.

The development of xanthan-konjac/agar gels and their analogs has been informed by early tests in several cross-specialty professional workshops and academic courses, providing key insights into how this versatile addition to the cleaning toolkit complements our established range of rigid gels, viscous polymeric solutions and spreadable gels, viscoelastic gels, and chemical hydrogels. Case studies from collaborators will be shared in another proposed submission.

A unique partnership comprising focal points from academia, chemical industry, non-profit, and private practice was carefully curated with specific expertise, capabilities, and priorities to advance safer solvent identification and education for cultural heritage use. The work highlighted within is a continuation of the “Safer Solvent Selections for the Removal and Application of Synthetic Resins” paper presented at the 2024 RATS Specialty Session of the annual AIC meeting.  The work justification and vision is unchanged from last year: conservators seek solvents for the application and removal of polymeric resins that a) are no/low-odor, b) have minimal health and environmental impacts and c) achieve the necessary solvation and film properties.

Previous work identified solvent blends that met rigorous GHS-defined safety criteria and demonstrated ranges of solvency for Laropal A81, PARALOID™ B72, and PARALOID™ B44. This presentation will provide the next stage of research with advanced solvent blend considerations, characterization of polymeric films properties casts from select blends, and Greener Solvents project partner feedback on test evaluations.  A dialogue with the AIC community is critical to bring this research into practice over time. We look forward to productive discussion that moves the field towards safer solvent alternatives that work.

Collaborations among scientists, conservators, and curators have been fundamental for understanding and conserving objects like from fine and modern arts. Those collaborations have been successful in many cases, but in others, have been limited especially due to challenges associated with team dynamics. Professionals from different fields may use different terminologies and have different understandings of how cultural items should be used, conserved, and studied. The challenges are intensified when considering the engagement with non-academics, who have other terminologies and may be personally and culturally attached to the cultural items. For example, collaboration with local non-academic Indigenous people may be vital when scientifically investigating cultural items of communities still practicing their traditions. But when, why, and how scientists can or should cooperate with them?

In my research group, we are investigating a still unknown blue colorant among technical art historians and conservation scientists (https://doi.org/10.3390/heritage7090222). Such colorant has been prepared by the Tikuna/Magüta people, who live in the Amazon Forest near the borders of Brazil, Peru, and Colombia. The ethnologist and anthropologist Curt Nimuendajú described in his book, published in the 1950s, that "the juice of one fleshy fruit (T., na’inku) furnishes a dark violet which, upon contact with iron, changes into a clear blue." To investigate materials like this, scientists usually select cultural items from museums for analytical investigation, try to make the colorant using the historical recipe, or get a sample of the colorant directly from the community. All those options consider the publication of the results in scientific journals, which are usually investigator-driven and academically centered strategies that generate benefits mainly for the researchers and their scholarly fields. However, the Tikuna/Magüta people are a living culture, still producing colorants from natural sources, and it is vital to consider their collaboration in the research for mutual benefits.

Among the different approaches for community-engaged research, we have been exploring community-based participatory research (CBPR). CBPR has social justice and empowerment at its foundation and considers community members' participation from formulating research questions to developing methods and collecting, interpreting, and using data. It considers power-sharing with the community members, is based on the community's strengths and resources, promotes reciprocity and mutual learning, considers the outcomes' sustainability, and disseminates results for all interested parties and partners. In these kinds of research, Indigenous members can participate as collaborators instead of subjects or sources of materials.

CBPR has been employed in fields like healthcare, archaeology, and education. Still, it has yet to be explicitly and systematically explored in technical art history and conservation science. In this presentation, I will address the challenges and benefits of CBPR in the context of technical art history and conservation science, based on our case study of the Tikuna/Magüta blue colorant and experiences of CBPR in other fields from different authors. With our work and this presentation, I also aim to stimulate discussions about how we can promote more socially responsible and inclusive practices in technical art history and conservation science.

Historically, museums are perceived as repositories for definitive knowledge on the objects they exhibit. As a result, artworks that conservators and curators have the most questions about often remain in storage and out of public view. At the Walters Art Museum (WAM), a shift towards showcasing objects with unresolved histories has fostered engagement and curiosity from visitors.

The unexpected results of a recent technical study of a Chinese lacquer screen prompted a reassessment of whether and how it could be displayed. Inscribed with the date 1681, the four-panel screen depicts the hermitage of fourth-century scholar Xie An. This type of lacquerware was popularized during the Kangxi period of the Qing Dynasty (1661-1722). Kuan cai, meaning “incised colors,” refers to the technique in which compositions are carved into a smooth lacquer surface and filled with colored paints. Kuan cai screens were first produced for the domestic market in Southern China in the seventeenth century. They are commonly known in the West as “Coromandel screens” or “Bantam work,” referring to two popular European-run trading ports in Southeast India and Indonesia from which they were first exported. 

Kuan cai screens are made from a complex layered system of wood, clay-based grounds, fabric and paper preparatory layers, lacquer, and oil-based paints. Due to their composite nature, damage from fluctuating environments, mechanical forces, and light is common. The WAM screen entered the collection in 2012 but has never been exhibited. Prior to acquisition, it underwent multiple restoration campaigns which now partially disguise the original surface. The goal of this technical study was to determine the composition of the screen’s original and restoration materials to draw inferences on dating and historic context. Multiband imaging, microscopy, radiography, fiber optics reflectance spectroscopy (FORS), x-ray fluorescence spectroscopy (XRF), scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDS), pyrolysis gas chromatography/mass spectrometry using tetramethylammonium hydroxide (THM-Py-GC/MS), and cross section analysis were completed.

While the screen was initially attributed to the seventeenth century, our results support the hypothesis that it was created during a later period. Radiography revealed an atypical construction with numerous nails attaching six horizontal cross bars on the verso. XRF showed the presence of zinc white in areas of white polychromy, while barium was detected in several passages of the screen in a variety of colors. Barium-based pigments were not available until the eighteenth century, raising questions about the screen’s dating and the extension of restoration. The absence of vermilion, orpiment, copper-based, and other commonly reported pigments was curious. 

WAM has established a precedent for displaying objects with pending questions. In the 2024 exhibition “Objects of Curiosity: What Will We Discover?,” visitors engaged in an ongoing conservation and curatorial investigation of artworks whose origin, authenticity, or utility were unknown. Taking inspiration from this exhibition, to tell the story of the lacquer screen we are developing didactic materials that reveal its layered history of use and repair. This approach to telling the stories of artworks situates visitors as active participants, rather than passive receivers of resolute information.

Recent discoveries of Patent yellow (also known as Turner’s yellow) a brilliant yellow lead-based pigment, in collection objects from The Colonial Williamsburg Foundation initiated research into the history and use of this under-researched colorant and an exploration of the most suitable analytical methods for its identification. Patent yellow’s precise introduction date and narrow window of use (1781 – ca. 1830) make it an important benchmark for dating and contextualizing objects, while recent documentary research shows it was an important and widely used inorganic yellow that may have been produced in the United States as early as 1783. However, it is little-known and rarely reported in conservation or art historical literature, possibly because lead (in the form of lead white) is ubiquitous on most historical painted surfaces, and chlorine, especially in the presence of lead, can be challenging to detect with techniques common to most conservation science laboratories such as XRF and SEM-EDS. Efforts to find and obtain reference samples of this pigment were fruitless, and attempts to synthesize it have, to date, been unsuccessful. These and other conditions can make this yellow frustratingly elusive to confirm. 

Collaborative analyses carried out at Colonial Williamsburg using cross-section and polarized light microscopy, XRF, and SEM-EDS, with further analysis using XRD and Raman spectroscopy at the Smithsonian Natural Museum of Natural History and the University of Delaware Microscopy and Microanalysis Laboratory have contributed to a better understanding of this pigment and challenges to its identification. Findings indicate its chief component is lead oxychloride (Pb7O6Cl2), consistent with Lorettoite, a (now-discredited) lead mineral, although other lead-oxide-chloride phases may be present. Raman and new XRD data for Patent Yellow have been obtained through this research, which has not previously been reported elsewhere in heritage science literature.  Photomicrographs of Patent yellow paint dispersions collected from case studies illustrate some previously unreported optical and morphological properties and demonstrate the effectiveness of polarized light microscopy in identifying this pigment, as it exhibits unique microscopic characteristics compared to other yellows, making optical microscopy a critical, simple, and effective first step in identification. Patent yellow case studies include varied decorative and fine art objects such as a painted coffeepot, a drum, a chair fragment, an easel painting by a Baltimore portraitist, and, most recently, a period room at the Museum of Early Southern Decorative Arts. This research suggests that Patent yellow/lead oxychlorides may be more common in painted surfaces than previously documented. It is hoped these findings can facilitate the identification of this pigment in other collections to better understand its broader use, properties, and role in late-eighteenth and early-nineteenth-century painted cultural heritage.

In 2023 the National Portrait Gallery in London (NPG) reopened to the public after undergoing the most extensive transformation of the building since the Gallery first opened its doors in 1896. The project, known as Inspiring People (IP), comprised a complete redisplay of the Collection, significant refurbishment of the building, the creation of new public spaces, a more welcoming visitor entrance and public forecourt, and a new learning centre.

One of the key aims of the building project was to enhance the visitor experience by the controlled re-introduction of daylight into spaces where windows had previously been blocked. At the same time, the new displays diversified the type of artworks on display, incorporating significant numbers works on paper and photography in the permanent galleries alongside paintings and sculpture. 

The engineering and design consultants Max Fordham were engaged to support the new vision for the Gallery. They created solar maps or ‘digital twins’ of the galleries simulating the natural light over a year using existing measured data as well as predicted future climate data. 

The modelling used a limiting illuminance (lux) and an annual exposure limit for artworks (klux.h per year) related to the light sensitivity of objects categorised as: 

2- Low responsivity (e.g. oil and tempera painting, wood, ivory) with a 200 lux limiting illuminance and 600 klux.h per year exposure limit, and 

3- Medium responsivity (e.g. prints and drawings, manuscripts, miniatures with a 50 lux limiting illuminance and 150 klux.h per year exposure limit). 

The use of annual exposure limits was new to the conservation team and required a shift in thinking as it did not align with the existing light sensitivity categories and exposure limits for objects at the NPG.

The digital twins allowed different methods of daylight control to be tested, including UV film, blinds, scrim and alternative settings for existing louvres. A range of different solutions were designed for different galleries, allowing curators to position category 2 light sensitive objects within the general gallery spaces. 

While modelling and planning was extensive, re-introducing and managing increased daylight across a range of differing display spaces is a complex undertaking requiring ongoing re-evaluation and adjustment. After opening, light monitors were placed into the galleries where category 2 objects were on display in spaces with natural light. Positioning of the sensors was a balancing act between aesthetic considerations for the re-displayed collection, and effective data gathering. With a year’s worth of data gathered since re-opening, these measurements can now be compared to the modelling by Max Fordham to assess the accuracy and review the parameters if necessary. 

This paper will discuss the challenges posed by the new approach to light management at the NPG and also the role of cross-team collaboration in the management and delivery of lighting projects.

Artifacts need to be stored somewhere, but there’s always a range of options from dirty basements to scorching attics with pests, mold, lead, and all sorts of other hazards and issues. It doesn’t happen in everyone’s career that they have to move an entire artifact collection, but usually when it does, they don’t get a choice on where the artifacts will be stored. Once in a great while, you get the opportunity to have a brand new custom storage facility, and if you’re REALLY lucky, then you’re included in the project to be able to advocate for the collection and how it will be stored. This was one of those times.

This was a construction project for a fully-roofed and insulated, three-hour fire-rated climate-controlled collection storage building inside of a “temporary” warehouse built in 1941. (We can see how well that temporary thing went.) To complicate this build further, this was to be done on a highly secure Naval base in Newport, RI. This complicates the process of finding contractors, getting people on base to do the work, getting construction equipment on the base, and what can even be ordered to be used for the project.

Thankfully, a trained conservator was brought into the project at the very beginning stages of it, making sure that every need was considered for the space to function best for the artifacts. Temperature, humidity, lighting, conservation equipment, sinks, door heights, exact high-density storage needs, fire suppression systems, office areas, etc. were all able to be considered in the beginning, instead of at the end, or not at all.

This talk will cover the struggles and triumphs from the very beginning of the project, through its completion. Unforeseen problems along the way will be discussed to help others in the future for their own considerations when completing a similar project. Conservators aren’t, generally speaking, also construction specialists, so hopefully, this talk will give some helpful tips to be considered in other collections’ construction projects.

On October 10th, 2019, at 8:30am, I started my job as Natural History Conservator at the Yale Peabody Museum. That same day at 11 o’clock, I had a meeting on how to protect the Age of Reptiles and Age of Mammals murals by Rudolph Zallinger during construction. This need for conservation knowledge and expertise continued for the remainder of the project, which ended in the spring of 2024 with the reopening of the entire museum after four years of closure.

Work during construction involved liaising with construction workers, architects, and engineers, as well as with museum leadership and colleagues. The conservation staff consisted of only me and one fellow initially focused on moving collections (and later on, on treatment of Anthropology objects). Partnerships with other departments that were not able to carry out their normal duties due to the pandemic, as well as with museum assistants made the work manageable and delegation of tasks possible. During this time, my lab at the museum was demolished and I had to move all my operations to the Shared Conservation Lab at Yale’s West Campus, as well as to a small museum classroom that was not to be renovated until the new Conservation triage space was to be built. In addition, object lists were being completed and exhibit layouts were being held by Exhibits with curators and collection managers, and me.

In 2022, I was asked a crucial question: what do you need? Being alone at the time, I answered: interns. In November of that year, the museum hired for the first time two pre-program interns for one year (positions that were later on extended). Their job was to be trained in the treatment of objects and specimens, to work on their portfolios, to have the experience of being in a renovation, and to learn what it is like to work in a museum. With my team in place, we started the impossible task of condition reporting and treating hundreds to thousands of objects and specimens with ever-changing object lists and gallery priorities.

This renovation taught me many things. As a colleague, it taught me to anticipate the needs of others. As a liaison, it taught me to speak in many other languages to get points across and to make those working with me get a sense of belonging. As a manager, it taught me that the more involved my team is in every aspect of the project, the more they will understand the bigger picture. As a mentor, it taught me to prioritize the education of the interns over the goals of the project. As a conservator, it taught me that you can always do more, but you have to learn to stop.

The Yale Peabody Museum reopened its doors in the spring of 2024 with a newly renovated museum. Conservation was involved early enough in planning but being new, I had to build trust with every person at the museum. To this day, I continue to work on this.

As museums across the country are redefining and diversifying their collections, curators and conservators are increasingly seeking new approaches to forging cultural relationships and community building aiming to decentralize Western perspectives and foreground Indigenous and community voices. Much like textiles, Indigenous or community-centered cultural materials have been marginalized, undervalued, and misrepresented within museum collections and the broader art historical narrative. Textiles are often deeply embedded in sacred spaces and communal practices, serving as repositories of spirituality, identity, and memory. These parallels position textile conservators to approach cultural collaboration with a unique understanding, compassion, and respect that can influence the wider conservation practices.  

Traditional museum practices present that the care of an object is commonly predicated on its “value and significance” in the greater art historical narrative. This approach requires a fundamental shift when considering community-centered cultural material, where significance is deeply tied to cultural and spiritual identity. Such a transformation involves not only revising traditional conservation methodologies but also rethinking institutional language and everyday interactions with these objects. Therefore, fostering a deeper connection with communities that created these artworks is essential to long-term preservation strategies. 

Textile conservators, through their specialized skills and historical perspective, are uniquely equipped to lead institutions in integrating Indigenous knowledge and perspectives into conservation and museum practices. By foregrounding cultural knowledge keepers as experts and decolonizing institutional language and procedures, textile conservators can help ensure that the conservation efforts respect and honor cultural practice. This includes recognizing contributions of the “nameless” artists or “Once Known Weavers” and “Once Known Artists”, whose historical significance has been obscured over time.  

This presentation explores the distinct role of textile conservators in fostering community relationships and reshaping institutional practices. It argues that textile conservation, with its long history of collaboration and sensitivity to cultural context, offers broader lessons for the conservation profession as a whole. By embracing cultural perspectives and incorporating them into conservation protocols, textile conservators can help museums establish deeper connections with communities and create more inclusive narratives. 

Drawing on examples from the work being undertaken at the Toledo Museum of Art, this presentation will demonstrate how these strategies are being implemented to build meaningful connections with Indigenous communities. Through collaborative efforts, we are amplifying community voices, enhancing transparency, and creating a greater sense of belonging within the institution. This presentation invites the broader conservation community to reflect on how these practices can reshape the future of conservation, ensuring that cultural preservation is as much about people and relationships as it is about objects.

For centuries, museums have been the accepted authority on Indigenous cultural materials and have acquired and amassed indigenous cultural items for their own use and benefit with minimal consideration from source communities. This structure is built on the foundation of colonization that show the public a version of history that is often disconnected from descendant communities and Indigenous ways of knowing. Further, the heart of every museum is its collections, which are expressed through avenues of conservation, stewardship, education, exhibition, and research. The values expressed in museum collections stewardship resonate throughout an entire institution and set the tone for how an institution operates.  

In 2021, the Indigenous Collections Care (ICC) working group was established to advocate for approaches that privilege Indigenous knowledge and respect and recenter concepts of culturally appropriate care for items in museum collections. These conversations transpired to the creation of the ICC guide, with its members consisting of diverse backgrounds, both Indigenous and non-Indigenous museum and academic professionals, tribal historic preservation officers, collections staff, and NAGPRA coordinators. The ICC guide is rooted in Indigenous perspectives and priorities, as well as practical applications. The document will not instruct museums on how to specifically care for each item, since protocols vary among communities, but will offer scalable considerations of culturally appropriate collections stewardship, with questions and talking points to address during a consultation, and with templates and case studies for use in implementation, advocacy, and the creation of policies and procedures. 

In dialogue with the conference theme, this paper focuses on years of collaboration between indigenous and non-indigenous museum collection professionals and source communities to develop the Indigenous Collections Care (ICC) guide. The development of the ICC guide is currently funded through an IMLS National Leadership Grant for Museums, under the School for Advanced Research (SAR). The guide will be available by 2026 and will be a free reference tool for preventive conservation and collection professionals that interact regularly with indigenous collections. Overall, the museum field has expressed a need for this resource. In a recent survey conducted by the Indigenous Collections Care (ICC) working group, 84% of collections professionals from a range of art, history, archaeology, historic preservation, and university backgrounds said an ICC guide would be highly beneficial to their institution. 

Museums can be places where ancestral connections are reawakened and relationships are built that create space where diverse Indigenous cultures and values are lived, protected, and respected.  The aim of conservation is the preservation of cultural heritage for future generations and should emphasize the rights of indigenous peoples to maintain and strengthen their own cultural traditions. In conclusion, reaching a larger museum audience in the conservation community, the presenters will discuss some of the foundational concepts of the ICC guide's content, and the process of the collaborative review sessions. Attendees will understand the value of culturally appropriate care, how the values expressed in collections and conservation stewardship resonate throughout an entire institution, and a pathway of how to incorporate these values into their daily work.

Solely focusing on Western Care for an Ethnographic Collection can be detrimental for the Relatives’ Belongings housed therein. 

The oldest belongings in Native American ethnographic collections are meant to be in use. These belongings, collected during a time when Native people were transitioning to a sedentary and oppressive life on reservations, were often traded for Western supplies required for survival in a new settler-colonial world.  

Much thought and intention went into the making of these Relatives’ Belongings. Designs and color choices unique to the tribal nation were chosen specifically for the wearer. 

With intention and thought embedded in the materials, the connection between the maker, the wearer, and the land is made. As most Native people believe that they are part of the land and the Earth is their mother/grandmother, this connection is representative of that relationship, that kinship.

Traditional care most often includes smudging (using medicinal plants important to Native people and gathered directly from the land) and feeding (sharing food and nourishment at community gatherings with relatives and with the Relatives’ Belongings, symbolically). 

In an active collection, community member visits add to the spiritual and physical care of a collection. Community members, relatives, will often sit with, talk with, and cry with their Relatives’ Belongings in a collection. They are allowed to hold their Relatives’ Belongings without gloves as a barrier. This contact with the Belonging creates connection. 

We have a partnership between the anthropology, facilities, safety, and collections stewardship departments to practice traditional care, including smudging in collections storage and reviewing historical pesticide treatments of Relatives’ Belongings.

Community members assist the Science Museum of Minnesota with the care of their Relatives’ Belongings. By including community members in the museum’s stewardship efforts, this museum and their collections staff are putting in work towards reparative actions. The museum does not own these Relatives’ Belongings. By acknowledging this fact, and speaking it aloud, the museum, more specifically the staff, can find common ground with community members. Most Native people are governed by values that they strive to meet in their everyday lives. With humility being a commonly held virtue, staff members practicing this belief does a tiny amount of bridging and acknowledges the very colonial nature of collecting institutions like museums. Traditional care of an Ethnographic collection challenges Western ideas of ownership and can minutely encourage shifts in perspective within museum culture. 

Traditional care is about access and honoring kinship.

A sizable collection of approximately three hundred Southwest Pueblo wooden figures (often erroneously referred to as “Kachina dolls”) were in a donation to start a Cultural Center – Museum. The figures are organic with wood, fur and feathers. Native Americans and conservators’ beliefs often differ drastically on what a collection piece is and how to treat the piece. The dilemma of the opposing views is visited in this abstract.

Many Indigenous Peoples believe everything has an animistic life force with a life cycle that ends in decay to then start another life cycle. The degree of life energy depends on various factors. Some of the most powerful animate sources are man-made entities made from re-purposed once living organic materials.

Conservation best practices when faced with a fragile fur and feathers collection that are susceptible to agents of deterioration, is to keep them in the dark in a temperature and humidity-controlled environment. Creating an securely enclosed mini-environment box that is light and humidity free, airtight boxes made of archival materials that buffer any extreme fluctuations in temperature or relative humidity would be ideal to preserve these figures. Yet, living animistic creatures want to stand upright, breathe, need light, and do not wish to be alone. The containers could not be regular boxes.

A solution of compromise resulted in the design of Culturally Sensitive Archival Containers.

The containers use all archival materials. Blue board is used to make a three-sided box and cover. UV restricting acrylic thermoplastic creates the front side permitting the entrance of light while restricting harmful light waves. There are breathe holes cut in the sides which are covered with unbleached cotton linen so pests and surrounding environmental factors are deterred. Two-inch plank Etha foam with Tyvek support the figures so they can securely stand and each container has two or more figures so they are not alone.

The container’s design considers the benefits of a mini-environment away from harmful light, pests, and other agents of deterioration while still considering the aspects of a living entity being able to breath in the light and not be alone. While both sides of this discussion compromise in the creation of these containers, the result is a good middle ground.

This journey brought an understanding of the pieces, their energy, and their care from a Native American’s view point while still accommodating the conservator’s ethics of good stewardship in combating the agents of deterioration. As we move forward in collection care, we must learn to listen and communicate. Both sides need to understand and accommodate views different than our own. These containers promote understanding between cultures and ideals. Most Native Americans are open to conservation practices if presented in terms of respect. In preserving collections conservators and stewards can give respect by listening. Maybe you too, will feel and hear the voice of the inanimate thing.

The Victoria and Albert Museum (V&A) has recently implemented a novel lighting policy (discussed in detail in VanSnick & Gaspar, 2024) - seeking to strike a balance between the display of light-sensitive objects and their long-term preservation. This work offers an evaluation of the practical rollout of the policy, refinement of process, and stakeholder uptake.

This policy works by whittling down collection on display to those objects that have the most pressing light vulnerabilities, looking experimentally at those objects, and using that new information to inform how we select vulnerable objects in the future. The first step is determining light vulnerability on a broad material level, flagging objects on display made from materials academically known to be highly light sensitive. These broad strokes are of huge benefit as it ensures that the first action of this policy will target those objects with the potential to be currently undergoing massive light damage. The second phase invites curatorial colleagues to assign a relative value each object in the group of highly light sensitive objects, allowing resources to be targeted in on the most exemplar objects which are materially assumed to be highly light sensitive. Where possible, objects that are highly light sensitive will be rotated out of display in a time period dependent on their rating value. Where rotation is not possible objects are examined experimentally using Microfademetery Testing (MFT).

Objects are unique in their vulnerabilities and these vulnerabilities are not as linear, consistent and predictable as one might expect. Experimentally analysing objects using MFT has the potential to bring their actual current light vulnerability into sharper focus. Given the vast size of the V&A’s collection, it is truly unfeasible to experimentally analyse every object - however this policy allows precise targeting of experimental resources to the places in the collection where they are most immediately needed. The lessons learnt about discrepancies between the assumed light sensitivity and the current experimental reality found are fed back into the initial stages of this process, allowing us to redirect resources to more vulnerable objects. For example, MFT conducted on Chinese, Japanese, and Korean lacquerware as part of this process has found this material to generally be drastically less sensitive to fading in practice than was academically thought. Not only does this mean that these objects can have far greater lifespans on display, improving access and ensuring we are focussing on the collections that need us most. 

This is not a static system - it is a cyclical process that edits and allows a more accurate picture of the collection’s sensitivities to coalesce in each iteration. It allows us to learn about our collection today and to react as the composition and the needs of our collection evolves over time.

The light sensitivity of works on paper is an important issue for any paper-based collection with regular exhibition cycles. The main concern is to protect the media from light-induced color changes, and MFT is a proven in-situ method for predicting these changes. As a substrate, however, white paper and especially rag paper is generally considered to be quite stable, with the exception of wood-containing and colored paper, which are considered light-sensitive according to the lighting guidelines. However, within the broadly defined class of white papers – which have been the most widespread worldwide since their emergence – there are also lignin-free white papers that are affected by moderate exposure to light. Our research group – three conservation scientists and five paper conservators collaborating from a print and drawing collection, a conservation science research laboratory, and two universities – studied typical light sensitivities related to compositions of paper and the ability of MFT to predict light-induced change in a broad range of the most typical white paper compositions.

We prepared nine sets of 37 papers divided into four compositional groups that represent papers across time. Three sets were aged in UV-filtered museum and commercial gallery exhibition-simulated settings (LED, mixed fluorescent/daylight, up to ca. 2.5 Mlxh), four underwent cyclic light-dark aging with or without pre-aging, and two sets were micro-faded by two commercially available MFT devices, one with a xenon source, the other a LED source. Using this test setup, we evaluated the influence of paper components on the color development of the papers during these different natural and accelerated aging conditions and compared them with the MFT results. The color change data of all exposures are given in Blue Wool Scale (BWS) by comparison to co-exposed Blue Wool Standards. 

Most white papers in exhibition simulation fell into the relatively stable BWS 2.5–4, but aged rag papers and papers containing ligneous and OBA papers ranged at BWS 1.–2.5. The predominant color change tended to be fading, but highly optically brightened (OBA) papers of low quality darkened. Groundwood and other high-lignin papers changed to yellowing after initial fading. Iron-contaminated papers without a significant alkaline reserve also tendentially darkened. Previous light-dark aging cycles had an effect on the type of color changes caused by light. Both MFT types and the cyclic light-dark aging predicted the papers’ sensitivity adequately compared to the simulated exhibition exposures and identified the most light-sensitive gelatin-sized rag papers and lignin-containing papers. However, predicting the color change of OBA-containing papers proved to be much less reliable. The color change of the papers that were exposed to LED in the exhibition-simulation was better reproduced by LED-MFT than by xenon-MFT or cyclic light-dark aging.  

We hope that the research results of the recently completed project will provide a clearer idea of the role of white paper in predicting the light sensitivity of artworks on paper using MFT. 

Our collaborative project was funded by the Germany Research Foundation 2021–2024.

Preservation Programs at the National Archives and Records Administration (NARA) investigated the characteristics of iron gall ink (IGI) in low or no-oxygen environments. NARA has vast holdings of 18th,19th, and early 20th century documents with iron gall ink. With the 250th anniversary of the Declaration of Independence, conservators and scientists seek to understand more about long-term display of sensitive IGI documents. In the past, NARA has used sealed anoxic encasements for some permanently-displayed iron gall ink documents. However, recent research into IGI behavior in anoxia [1] as well as material and structural differences between the majority of paper-based documents in NARA's holdings and other treasured national records on parchment meant that the use of a low oxygen display environment needed to be examined. 

Scientist Bruce Ford previously demonstrated that fading of iron gall ink is somewhat reversible in the dark but that anoxia diminished this reversion potential. His experiments exposed ink to light levels equal to several decades of display exposure, followed by a period of darkness that allowed ink to revert overnight. We sought to conduct a similar experiment, but with a closer match between typical exposure and rest periods to exhibit conditions. Additionally, we wanted to know if IGI reversion potential could ever be exhausted or would change with past treatment history. Subsequently, we designed experiments using an automated LED MFT (2700K white LED, ~3.1Mlux) in an atypical manner. We repeatedly exposed 19th century, post U.S. Civil War era, non-record samples and paused for reversion periods in the dark on the same spot. We tracked incremental and overall change in color (ΔE00) and L*a*b* color space parameters. We also tracked and controlled temperature and humidity as much as possible to prevent movement during test periods (up to 1.5 weeks) and kept the dose for each exposure as low as possible (0.04-0.4 Mlux-hrs.), only inducing enough change required for reasonable signal to noise ratios. We performed mock de-silking and delamination treatments on historic samples to mimic the condition of many NARA holdings. Treated ink required higher dosages of light to induce the same amount of change as non-treated IGI. We conducted multiple cycles of low-dose MFT both in air and anoxia and were able to reproduce Ford’s result showing reversion in air, and significantly reduced reversion in anoxia. We investigated the nuances of reversion in each of L*, a* and b* under each condition. After several tests in anoxia, we reintroduced oxygen up to 2% concentration which showed a returned ability to revert. MFT results were also compared to an experiment with 2 klux LED lamps (up to 4.5Mlx-hrs) where no visible change was observed. This indicated reciprocal failure, however these results still have important implications for display design options for iron gall ink records.

Works Cited

1. Ford, B. 2014. “The accelerated light fading of iron gall inks in air, hypoxia and near-anoxia.” In ICOM-CC 17th Triennial Conference Preprints, Melbourne, 15–19 September 2014.

Joe Overstreet (1933-2018) was an innovative artist who defied easy categorization. Interested in art from a young age he studied in California at different institutions but by 1958 he felt he had outgrown the West Coast and moved to New York where he became friends with many of the abstract expressionists and color field painters working there. Always politically motivated, many of his works from the 1960s directly referenced the civil rights movement, some such as The New Jemima(1964) are overtly figurative whereas others, such as 16th Street Birmingham (1963) and Strange Fruit (1965), are more abstract. In the late 1960s, urged by Frank Stella and Sam Gilliam, Overstreet began to create shaped, unprimed canvases painted in acrylic with bold geometric patterns that referenced his African and Shoshone heritage. These works, exemplified by North Star(1968) and Justice, Faith, Hope and Peace, presaged his growing interest in the sculptural possibilities of paintings. In his next, perhaps best-known series of works Overstreet freed himself from the stretcher altogether. His mandala paintings, such as Hoo Doo Mandala(1970), retain the geometric patterns of the shaped canvases but are stretched onto the surface of the wall. His slightly later flight patterns incorporate the soak-stain approaches of Gilliam and Frankenthaler and are held in taut geometric shapes through ropes attached to the walls, floors, and ceiling. Overstreet indicated that his use of ropes referenced both construction techniques used by Ancient Egyptians, and the ropes used in lynchings, while his desire to create easily transportable works was an homage to his nomadic ancestors who survived with our art by rolling it up and moving it all over."The founders of the Menil Collection, John and Dominique de Menil had a long association with Overstreet, purchasing The New Jemimaand several flight patterns. Through this connection he was invited by Larry Rivers to participate in the 1971 Some American Historyexhibition and in 1972 Dominique organized a solo show of Overstreets works at the Rice Institute for Arts. In 2025 the Menil Collection will open Joe Overstreet: Taking Flight,which brings together shaped canvases, mandalas, flight patterns and his seminal late series of oil paintings made after visiting Senegal in 1992. This exhibition, and access to Overstreets artworks and studio materials provided by the Eric Firestone Gallery and Corrine Jennings, Overstreets partner, provided an unparalleled opportunity to begin to examine Overstreets materials and methods. Overstreet said that My work has changed every picture I've ever made, because I'm searching for the unknown truth, but how did his materials and methods change over time? Non-destructive analysis by XRF and limited sampling revealed a shift in pigments, and an increasingly complicated painting process as he moved from shaped canvases to mandalas to flight patterns while his Senegal series marks a return to the use of oils, particularly those of the New Holland line. This is the first in-depth study of this seminal artists practice and helps reveal the various ways he sought to express his truth.

Beginning with his Nocturnes, Whistler began diluting his oil paint with a secondary medium he referred to as his “sauce.” Such a fluid medium allowed the artist to work wet-in-wet, and facilitated scraping, rubbing, and scumbling. While there are primary source references to copal being used in his “sauce,” there have been no technical studies that have identified copal as an ingredient that Whistler employed. In the 1980s and 1990s, Stephen Hackney and Joyce Townsend collaborated on a series of technical studies on paintings by Whistler in the Tate, National Gallery of Art, and Hunterian Art Gallery, among others. Their research did not find any evidence of copal, instead determined that turpentine and mastic varnish were added to the oil paint to create the sauce.

The four Nocturnes in the Harvard Art Museums’ collection (1943.171, 1943.172, 1943.173 and 1943.176) were completed over the course of the 1870s. The paintings are significantly understudied, largely due to their inclusion in the Winthrop collection, which stipulates their continuous display in the galleries and prevents their travel. The closure of the museum during the pandemic provided a rare opportunity to study the paintings. This research aimed to contribute up-to-date material analysis to compare with primary sources and build on the work of both Hackney and Townsend.

A small set of samples were taken from each painting and were either prepared as a cross-section or analyzed by thermally assisted hydrolysis and methylation pyrolysis-gas chromatography mass spectrometry. A comparison of the data has revealed some insight into Whistler’s painting materials and technique for this set of paintings. In darker compositions (1943.171 and 1943.173) multiple layers of media rich paint, some of which were unpigmented and all varying in thickness, were applied. This is in contrast to lighter compositions (or areas, 1943.172 and 1943.176) where single, relatively thick, pigment rich layers were applied. In these layers the addition of organic media was observed, in patches or waves, suggesting incomplete mixing. Pinaceae resin, may at the very least be suggested to be part of Whistler’s ‘sauce’ based on the analysis conducted here. Using written accounts as a guide the use of turpentine could be suggested, which would result in a more fluid paint medium which is a characteristic of Whistler’s paint. Analysis also suggests the recipe for Whistler’s sauce was not fixed, with evidence found for the incorporation of bleached shellac (1943.171) and perhaps mastic (1943.172) into the paint in some but not all of the nocturnes.

The Courtauld Gallery’s version of Edouard Manet’s iconic painting Le Déjeuner sur l’Herbe is perplexing. It has long been thought to be a copy created after the iconic large-scale French masterpiece of the same title; a work described as a founding moment of modern art by the last great old master. The Courtauld’s smaller work, painted “in a curiously harsh and hasty style” (Wilson-Bareau, 1986), and the large Musee d’Orsay canvas has long been a subject of scholarly debate. The Courtauld canvas has indeed been considered to be a preparatory sketch, a later replica of the d’Orsay version, or even a copy by a later hand

This Courtauld “sketch” was purported to have been commissioned by a close friend of Manet, Commandant Hippolyte Lejosne. However, according to the Gallery archival records the Courtauld painting was understood to be a gift from the artist to his friend. Following the Commandant’s death, the Lejosne family (of Maison-Lafitte) approached the Galerie Duret, one of Manet’s key dealers in Paris, who took the work on commission. In June 1928, the small sketch was brought to the attention of Samuel Courtauld by his principal art advisor and top London art dealer, Percy Moore Turner. Mr. Courtauld purchased the painting, and later, in 1932, bequeathed it to the newly formed Courtauld Gallery

Although signed by Manet in the lower left, scholarly debate has also extended beyond the painting function and onto questions over attribution. Much has been written about the narrative and symbolic meaning behind the making Le Déjeuner sur l’Herbe but the ambiguous status of the Courtauld work is in no small part due to the fact that the painting had not the focus of a materials investigation, nor had it been painting treated in the Courtauld Conservation studio for over four decades. Now, after an in-depth material investigation and the full conservation treatment this paper endeavours to explore the relationship of the Courtuald’s painting to the largescale signature work housed in the collection of the Musee d’Orsay.

This paper is a typical collaborative story between art history, science and conservation. Working closely with the curator, the conservator and the conservation scientist considered the painting materials and artistic working practice in an attempt to shed new light on the meaning behind the making of Courtauld’s version of Manet’s iconic work. Using new techniques, such as macro-XRF scanning and steadfast archival research methods, it hopes to propose a possible chronology by looking at the notions of the artist’s sketches, working as well as later copies and finally look at the possibility of replicating by another hand.

Red-figure pottery is a type of ancient Greek ceramic that originated in Athens in the later 6th century B.C. It typically features decoration in diluted clay slip that turns black after firing and is painted on a clay body that appears reddish orange. This kind of ware was used in daily life, dedicated in sanctuaries, and placed in tombs. The “red” areas contain hematite (Fe2O3), and the black background contains magnetite (Fe3O4) and hercynite (FeAl2O4). The red and black designs of Attic pottery have been shown to result from a complex firing process involving cycles of oxidation, reduction, and reoxidation. Initially, fine-grained red hematite is reduced to a dense, vitrified layer of black magnetite and hercynite, which resists reoxidation. In the final oxidation step, only the coarse-grained, porous ceramic body reoxidizes to red hematite, creating a sharp contrast between the red figures and the glossy black background (1–3).  

The Harvard Art Museums house an impressive collection of Athenian red-figure pottery. This includes the focus of this study, the so-called Bouzyges krater (1960.345), a 5th century B.C. mixing bowl for wine and water, named after the protagonist of the mythological scene depicted on its front. Although there are areas of well-preserved red-figure decoration on the krater, other areas display various levels of discoloration. The pronounced differences between adjacent sherds suggest that some alterations occurred after the vessel was broken, likely due to its involvement in a cremation burial. In such burials, ceramic vessels, often used as grave goods, were likely thrown onto the pyre and then swept into the burial, leading to the discoloration seen on the krater. Funeral pyres can reach temperatures up to 1000 ⁰C, creating a partly reducing environment due to the evolution of carbon monoxide and dioxide from burning bodies (4). It is to be expected that the temperature and oxidation/reducing environment will vary across the pyre, causing the broken fragments to display different degrees of discoloration. On some fragments, the red ceramic is altered into grey due to the reduction of hematite. On others, the black gloss is partially altered into red, suggesting high-temperature oxidation of the iron oxides occurred in areas of the fire where oxygen was more abundant.  

The disassembly of this vessel as part of its conservation treatment provides an ideal opportunity to study the krater, shedding light on the high-temperature material changes observed from the surface of the slip to the bulk of the ceramic. Using techniques such as SEM-EDS, X-ray diffraction, Raman, and FTIR spectroscopy, this material study will be important for the conservation of similar ceremonial vessels, furthering our understanding of their involvement in ritualistic practices. 

References 

1. R. Jones, Adv. Archaeomaterials. 2, 67–127 (2021). 

2. M. Walton et al., J. Am. Ceram. Soc. 96, 2031–2035 (2013). 

3. S. Balachandran, Arts. 8, 70 (2019). 

4. M. S. Walton, M. Svoboda, A. Mehta, S. Webb, K. Trentelman, J. Archaeol. Sci. 37, 936–940 (2010).