Conservation Strategies for Palm-Leaf Manuscripts from Yunnan, China
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Yan Li
,
Guanghui Yang
Abstract
Palm-leaf manuscripts served as a primary documentary medium across South and Southeast Asia prior to paper’s ascendancy. China’s Yunnan and Xizang regions preserve significant collections of these cultural artifacts; however, standardized conservation protocols remain underdeveloped. This investigation pioneers systematic analysis of incised palm-leaf manuscripts in Yunnan repositories, establishing a novel typology for damages and corresponding customized conservation strategies. Through empirical examination, five characteristic types of deterioration were identified. Aiming at restoring the structural integrity and functionality of palm-leaf manuscripts, the conservation strategy integrates damage classification, cleaning and stain removal, repair and reinforcement, flattening, binding restoration, and protective housing. The results demonstrate that composite fillers (palm-leaf’s powder, pulp, fiber strip, and infills) with chemical composition and physical properties matching those of the manuscript, ensure the compatibility of the repair materials. Additionally, the adhesives used in this study can be safely removed under specific conditions, effecting the reversibility of the intervention. These materials have sufficient durability under standard preservation conditions, ensuring the long-term stability of the restored areas. This study not only provides a feasible technical path for the conservation of palm-leaf manuscripts in Yunnan but also offers important guidance and references regarding conservation and preservation research for institutions worldwide that collect engraved palm-leaf manuscripts.
Zusammenfassung
Palmblattmanuskripte dienten in ganz Süd- und Südostasien als primäres Dokumentationsmedium, bevor sich Papier durchsetzte. In den chinesischen Regionen Yunnan und Xizang werden bedeutende Sammlungen von Palmblattmanuskripten aufbewahrt, standardisierte Restaurierungstechniken sind jedoch noch nicht ausreichend etabliert. Diese Untersuchung leistet Pionierarbeit bei der systematischen Analyse von Palmblattmanuskripten mit eingeritzter Schrift in Yunnan, indem sie eine Schadensklassifizierung und entsprechende, maßgeschneiderte Erhaltungsstrategien entwickelt. Durch empirische Untersuchungen konnten fünf charakteristische mechanische Schadenstypen identifiziert werden. Mit dem Ziel, die strukturelle Integrität und Funktionalität von Palmblatthandschriften wiederherzustellen, umfasst die Restaurierungsstrategie die Aspekte der Schadensklassifizierung, Reinigung und Reduzierung von Verfärbungen, mechanischen Verstärkung, Planlegung, Wiederherstellung der Bindung und Verpackung. Die Ergebnisse zeigen, dass die Kompositfüllstoffe (Palmblattpulver, Zellstoff, Faserstreifen und Intarsien), deren chemische Zusammensetzung und physikalische Eigenschaften denen von Palmblattmanuskripten entsprechen, die Kompatibilität der Ergänzungsmaterialien gewährleisten. Außerdem sind die in dieser Studie verwendeten Klebstoffe reversibel und können unter bestimmten Bedingungen sicher entfernt werden, wodurch die Rückführbarkeit der Restaurierungsmaßnahmen gewährleistet ist. Diese Materialien haben eine ausreichende Haltbarkeit unter üblichen Aufbewahrungsbedingungen, sodass die langfristige Stabilität der bearbeiteten Manuskripte gewährleistet ist. Diese Studie zeigt nicht nur einen umsetzbaren Ansatz für die Restaurierung von Palmblatthandschriften in Yunnan auf, sondern bietet auch wichtige Anhaltspunkte und Referenzen für die Restaurierung und Konservierung von Palmblatthandschriften mit eingeritzter Schrift in Institutionen weltweit.
1 Introduction
Palm-leaf manuscripts (PLMs) originated in ancient India and subsequently disseminated to South Asia and Southeast Asia. In the 7th century, they were introduced to the Dai region of Yunnan and the Xizang autonomous region in China (Huang and Zhang 2020). These manuscripts exemplify the outcomes of cultural exchange and integration and constitute a significant component of ancient literature. The Yunnan province, situated at the confluence of the Chinese cultural sphere and the South Asian and Southeast Asian cultural spheres, occupies a unique geographical position. It serves as an important gateway for China’s engagement with South Asia and Southeast Asia and functions as a geographical nexus for the three major linguistic systems associated with Chinese Buddhism, Tibetan Buddhism, and Theravada Buddhism. The diverse cultural and religious milieu of Yunnan has rendered palm-leaf manuscripts not only crucial repositories of Buddhist scriptures but also records of the region’s political, economic, and social life. These manuscripts hold significant historical and cultural value, and their preservation and continuation are of great importance.
Xishuangbanna in Yunnan is the principal center for the preservation and continuation of PLM production techniques. This craft was inscribed as a national intangible cultural heritage of China in 2008. PLMs in Yunnan are predominantly written in the ancient Dai script, which incorporates both the indigenous Dai language and Pali language. The content primarily centers on Theravada Buddhist scriptures. These manuscripts are chiefly housed in local Theravada Buddhist temples and continue to be utilized for ritualistic purposes, thereby fully reflecting their dual significance in both religious and cultural contexts. The content of these manuscripts encompasses a wide range of disciplines and serve as indispensable primary sources for academic research. Many of these manuscripts are rare editions with significant documentary value (Zhang et al. 2022a; Lyu and Zhang 2020).
The manuscripts are crafted according to traditional local techniques, encompassing both those made from talipot palm leaves and those produced on paper. Paper-based manuscripts are exclusively written by hand, whereas leaf-based manuscripts are engraved. The production of engraved manuscripts primarily utilizes talipot palm leaves as the main raw material and involves a series of intricate processes, including trimming, boiling, cleaning, drying, punching, flattening, engraving, inking, and binding (Yu et al. 2024). This study focuses on engraved PLMs from Xishuangbanna, which are created using a stylus-like instrument to inscribe text onto the palm leaves.
Due to their organic composition, PLMs are susceptible to a variety of challenges during long-term preservation (Nichols 2004; Sharma and Singh 2018). These challenges include substrate deterioration, biological attack, physical damage, improper handling or transportation, particularly in the humid and hot climate of South and Southeast Asia, where environmental conditions accelerate the deterioration of PLMs. Common types of damage such as staining, infestation, tearing, material loss, and fraying fibers significantly impede both their usability and long-term preservation (Lyu and Zhang 2020). Contamination refers to surface stains on PLMs caused by improper storage conditions or external contact. Typical contaminants include water stains, oil spots, mold growth, and microbial residues. While water and oil can infiltrate the fiber structure, they do not alter the fibers’ cohesion in the same way as mold and fungi. Biological contaminants, particularly mold and fungal growth, can secrete extracellular substances that bind fibers together, leading to adhesion between leaves. In advanced stages, this process may cause fiber degradation, ultimately compromising the structural integrity of the manuscripts. These contaminants not only impair the readability of the manuscripts but may also penetrate the fiber structure, causing the leaves to adhere to one another and, in severe cases, damaging the fibers and reducing the physical integrity of the manuscripts. Pests such as booklice, termites, and borer cause small areas of loss in the PLMs, creating irregular perforations that compromise the structural integrity and readability of the PLMs and may further exacerbate their fragility. Cracks are usually the result of aging or external forces, leading to material deterioration of the PLM leaves which may result in cracks or breakage. If not promptly repaired, these cracks may expand, leading to the loss of textual content. Material losses are often caused by biological attack (including rodent feeding and insect damage) or external mechanical forces, typically manifesting as frayed edges. This not only affects readability but also detracts from the aesthetic appearance of the manuscripts. Material aging or external friction result in fraying, i.e., fiber splitting and curling, which form filamentous structures. Fraying fibers further compromise the integrity of the manuscripts and increase the complexity of conservation efforts. To address these damages, appropriate materials and methods should be carefully selected based on the specific condition of each manuscript to maximize the restoration of both functionality and aesthetic value.
Currently, the conservation efforts for PLMs in China primarily concentrate on their collection, organization, cataloging, and reproduction, as well as the preservation of relevant traditional craftsmanship associated with PLM production. However, there is a notable deficiency in the literature concerning theoretical, experimental, and practical conservation techniques and material selection for PLMs. In this work, the experiences and accomplishments of research in India, Europe, and America on the conservation of similar cultural heritage materials could provide valuable insights and guidance for the conservation of PLMs in China. The public reports and research studies are mainly focused on the following aspects:
Areas of loss: When repairing areas of loss in PLMs, smaller areas are typically filled with mulberry tissue paper and adhesives such as methyl cellulose (MC), followed by additional reinforcement with Japanese paper (Agrawal 1984). Larger areas may require blank palm leaves and polyvinyl acetate (PVAC) adhesives for repairing (Harinarayana 1995). In cases of severely damaged PLMs, a leaf-casting machine can be utilized in conjunction with colored pulp, while for slightly damaged PLMs manual pulp filling is viable (Joshi 1989; Jurkiewicz 2017).
Cracks and tearing: When mending cracks and tears in PLMs, Japanese papers such as Kozo and Mitsumata papers are frequently employed along with adhesives like methyl cellulose (MC), starch paste, ethylene-vinyl acetate copolymer (EVA), and isinglass. The repair paper is customarily dyed to match the original manuscript as needed (Takagi et al. 2006; Jacobs 2010; Wiland et al. 2023). Silk gauze, chiffon, or tissue paper, in combination with acrylic rubber, acrylic emulsion adhesive, or starch paste are also used for conservation purposes (Sah 2002). Another method involves mixing new palm leaf powder with polyvinyl acetate (PVAC) to create infill material for repairing damaged leaves (Wiland et al. 2023). Additionally, sewing, a traditional Asian method, is commonly employed for the conservation of damaged PLMs (Wiland et al. 2022).
Material Loss: There are three main methods for filling areas of loss in PLMs. The first method involves the use of handmade paper for repair, with Japanese paper and Thai mulberry tissue paper being the most widely used materials. These papers are layered to match the thickness of the palm leaf, making them suitable for repairing both small and large areas of loss (Wiland et al. 2023). During the conservation process, these papers are often combined with adhesives such as polyvinyl acetate emulsion (PVAC) (Agrawal 1984), polyvinyl alcohol (PVA), ethylene-vinyl acetate (EVA) (Sah 2002), methyl cellulose (Takagi et al. 2006), and wheat starch paste (Poirier 2020). The repair paper can also be dyed to enhance the aesthetic appearance. The second method involves attaching pieces of palm leaf to areas of loss with a 2 mm overlap (Wiland et al. 2022) or inlay (Zhang et al. 2022b), and combined with adhesives such as EVA, PVAC (Agrawal 1984), PVA (Sah 2002), and Cascamite® (an ureaformaldehyde resin) (Wiland et al. 2022). The third method involves the use of bark materials, such as birch bark (Wiland et al. 2023) or the inner layer of mulberry white bark (Nichols 2004), which are cut according to the shape of the area of loss. During the conservation process, two layers of wood bark are overlapped, with a layer of Japanese Kozo-shi paper (Crowley 1969) in between, or covered with Japanese Mitsumata paper (Jacobs 2010), and fixed with adhesives such as acrylic emulsion, wheat starch paste and PVA.
Fraying fibers: When stabilizing fraying fibers, various toned Japanese papers of different weights are used, along with adhesives such as wheat starch paste, methyl cellulose, fish glue, or isinglass (Wiland et al. 2022, Wiland et al. 2023). Historically, pressure-sensitive tape was occasionally applied for such repairs; however, its long-term stability issues, including adhesive degradation and staining, have led to its discontinuation in professional conservation practices.
Other types of damage: In cases of aged and brittle PLMs, materials such as silk gauze, chiffon, and Japanese paper are commonly used for backing, and adhesives such as PVA (Sah 2002), wheat starch paste (Agrawal 1984) or acrylic emulsion (Crowley 1969) are employed. These materials and adhesives are still widely used in contemporary conservation practices. In contrast, historical methods such as cellulose acetate lamination, the use of solvents like acetone for single-sided lamination, and thermal lamination techniques at temperatures between 60 and 70 °C (Gupta 1974) are now largely discouraged due to their irreversible nature and potential to cause long-term structural damage.
Although the conservation methods for PLMs described in literature are diverse, they lack standardized criteria and guidelines, thereby limiting the effectiveness of their implementation. This limitation is particularly evident in the mismatch between repair materials and the original materials of the PLMs. Moreover, the long-term stability of certain repair materials is a significant concern. For instance, adhesives such as acrylic emulsion, acrylic rubber, and Cascamite® ureaformaldehyde resin exhibit limited reversibility after curing, thereby increasing the risk of the adhesive being difficult to remove. Additionally, existing methods are not classified according to the specific types of damage to the PLMs, resulting in a lack of targeted repair measures. Therefore, it is of great practical significance to develop methods that can effectively restore the visual balance of the PLMs while ensuring long-term stability. To conclude, this study explores conservation strategies that match the structure and appearance of PLMs and formulates corresponding repair strategies for different types of damage, thereby addressing the aforementioned issues.
In response to the identified deficiencies in existing conservation techniques, this study has undertaken a comprehensive analysis of prevalent conservation methods and has formulated targeted improvement strategies. These strategies are detailed as follows:
Long-term ageing characteristics and reversibility of used materials: Some suggested materials, such as acrylic emulsion, acrylic rubber, and Cascamite®, exhibit limited reversibility after curing (Sah 2002; Wiland et al. 2023), potentially introducing uncontrollable risks during long-term preservation. To mitigate this issue, this study has identified materials that maintain reversibility under high-temperature and high-humidity conditions. These materials can be safely removed under specific conditions, thereby ensuring the reversibility of the conservation process. Moreover, under conventional preservation conditions, these materials provide sufficient durability to guarantee the long-term stability of the treated areas. Furthermore, this study has utilized conservation materials that closely replicate the original materials of the manuscripts. These materials have been subjected to rigorous processing protocols to precisely match the chemical composition and physical characteristics of the original materials. This meticulous approach ensures optimal compatibility and long-term stability between the conservation materials and the original manuscripts, thereby preserving their integrity and performance.
Filling in small area losses: Existing conservation techniques, such as those utilizing paper pulp made from mulberry paper and methyl cellulose (Agrawal 1984), can effectively fill in small areas of loss and cracks. However, it may be difficult to achieve perfect color and texture matching to the original PLMs with these materials. To address this limitation, this study employs palm leaf pulp, leaf powder, and leaf fiber strips as conservation materials. These materials not only maintain visual consistency with the original manuscripts but also provide adequate physical support to ensure the stability of the treated areas. Additionally, they facilitate a natural transition in texture and appearance with the original manuscript.
Filling in large areas of loss: For filling in extensive areas of loss, existing methods typically rely on paper or bark materials for filling (Crowley 1969; Jacobs 2010; Nichols 2004). While these materials can offer some physical support, they are limited in their ability to restore visual effects and the original appearance. To better match texture and appearance of the manuscripts, this study opts to use palm leaf materials that are consistent with the original. Through meticulous dyeing treatments to adjust the tone, the infills match the color and texture of the original manuscripts. By integrating leaf pulp and leaf powder, seamless integration between infill and the original material is ensured, effectively restoring the integrity of the manuscripts.
Through these enhancements, conservation methods developed in this study are designed to surmount the limitations of traditional techniques, particularly in material selection and conservation outcomes. It is our expectation that this approach will effectively rehabilitate the physical integrity of palm-leaf manuscripts and safeguard their historical and cultural significance to the greatest possible extent.
Based on the foregoing analysis, this study aspires to offer an adequate conservation strategy for Yunnan PLMs. By conducting in-depth research into the types of damage and integrating international best practices, a comprehensive set of conservation solutions with local, cultural, and practical relevance will be formulated. It is our hope that this study will provide a robust theoretical foundation and technical support for the conservation of Yunnan PLMs. Moreover, this work aims to offer fresh insights and practical examples for institutions in China, South Asia, Southeast Asia, and globally that collect comparable PLMs.
2 Comprehensive Conservation Strategy
2.1 Theoretical Basis and Core Principle
The conservation strategy proposed in this study is firmly grounded in the core principles of manuscript conservation, namely “restoring the document as its original state prior to damage, intervening minimally, prioritizing reversibility and ensuring safety” (Lin, Zhou, and Zhang 2012). Building on this foundational framework, this study has developed bespoke conservation strategy tailored to the specific damage conditions of each palm-leaf manuscript, considering their material characteristics and long-term preservation requirements. This strategy is designed to ensure that the conservation meets stringent scientific standards while also honoring the cultural and historical significance of the manuscripts.
Firstly, to ensure the targeted and effective nature of the conservation work, this study conducted a detailed classification of the types of damage of the PLMs prior to implementation of conservation measures. This classification was based on specific types of damage present on each manuscript, such as material losses caused by pests and rodents, cracks resulting from external forces or aging, losses due to biological attack, or fractures and fiber fraying caused by aging and friction. The classification also considered the characteristics of the materials and their preservation needs. Consequently, tailored measures restore the visual balance of each manuscript, accounting for the different types of damage, ensuring the suitability and appropriateness of the conservation strategies and avoiding the use of a one-size-fits-all approach, thereby enhancing the efficacy of the conservation work without compromising the effectiveness of the treatment.
Secondly, the principle of “restoring the document as its original state” emphasizes the importance of maintaining the historical accuracy of the document throughout the conservation process. In alignment with this principle, this study prioritizes the use of materials identical to the PLMs themselves to ensure the preservation of their historical and cultural significance. Additionally, this study pays attention to retaining the original binding form of the manuscripts. In order to achieve that, the conservation process strictly adheres to traditional craftsmanship to ensure the integrity and completeness of the manuscript.
Thirdly, the principle of “minimal intervention” emphasizes the importance of preserving the original appearance of the document during the conservation process. To this end, this study conducts a detailed classification of the types of damage, adopts targeted conservation measures according to different types of damages, and strictly controls the amount of materials used to minimize the degree of intervention on the PLMs. This approach not only ensures the authenticity of the document but also avoids potential secondary damage that may be caused by any additional harm from excessive intervention.
Lastly, the principle of “prioritizing reversibility and ensuring safety” plays a crucial role in manuscript conservation. To ensure the reversibility of the conservation measures, this study selects adhesives that may be easily reversed in high-temperature and high-humidity environments. This deliberate choice not only ensures that conservation treatment can be safely undone under specific conditions but also minimizes the potential risks associated with material aging or environmental fluctuations, thereby meeting the essential safety standards for document conservation. These adhesives not only exhibit excellent properties in the short term but also effectively control the risk of damage caused by aging or environmental changes during long-term preservation.
By integrating these conservation principles with practical implementation, this study aims to achieve a harmonious balance between functional restoration and long-term preservation while respecting the historical value of PLMs.
2.2 Selection of Materials
In the conservation process of PLMs, the selection of materials is intrinsically linked to the success of the conservation outcomes and the long-term preservation of these manuscripts. This study has carefully evaluated the unique material characteristics of PLMs and the specific types of damage they exhibit. By adhering to the principles of compatibility, stability, and reversibility in the selection of conservation materials, a diverse range of suitable options has been identified. The following detailed analysis will underscore the key characteristics and advantages of the selected materials.
2.2.1 Selection of Palm Leaf Materials
A variety of conservation materials, including Japanese paper (Crowley 1969), paper pulp (Wiland et al. 2023), palm leaf pulp, and palm leaf pieces have been suggested for treatment of palm leaf manuscripts. The visual comparison highlights the significant advantages of using palm leaf pieces for infills, particularly in ensuring visual consistency between infill and original material (Figure 1). To ensure the compatibility of materials with the original documents, blank, newly processed palm leaf sheets that are made from the same material as historical PLMs were selected. These selected sheets undergo initial processing steps such as trimming, boiling, cleaning, drying, and pressing to retain their natural flexibility and strength (Yu et al. 2024). During the conservation process, special attention was paid to factors such as the type of leaf, leaf surface, and degree of dryness. These factors play a crucial role in the stability of treatment results and long-term preservation. Differences in dimensions, thickness, moisture absorption, and physical properties of different palm leaf sheets, especially their performance during the conservation process, may impact the results. To ensure the stability and durability of conservation materials, suitable palm leaf sheets were carefully selected to ensure their physical properties are stable by strength performance tests, and their dimensions and thickness match the original material of PLMs, thus ensuring compatibility of the introduced materials and the long-term sustainability of the treatment.
Comparison of different conservation materials on damaged PLMs. (a) palm leaf pulp and (b) palm leaf pieces.
To achieve this effect, newly processed, blank palm leaf pieces are dyed to better integrate with the original documents. However, the decision to dye infill materials should be made judiciously, considering the specific requirements of the conservation project and its long-term preservation objectives. In the dyeing process, different techniques such as black tea, Chinese painting pigment, and artificial aging treatment were compared. The results demonstrate that the use of Chinese painting pigments for dyeing yields the most effective results (Figure 2). Drawing inspiration from dyeing methods employed in the conservation of traditional Chinese ancient books and paintings, pigments such as ochre, gamboge (藤黄) and Chinese indigo (花青) were utilized along with ink and alum size. Ochre is a mineral pigment with good stability, excellent coverage, and resistance to fading. Gamboge (藤黄) and Chinese indigo (花青) are plant-based pigments with transparent and pure colors, commonly used for base coating and shading. To ensure uniformity and stability of dyeing effects, an alum–gelatin solution was used as a dyeing auxiliary in the research. This solution serves both, uniform toning and enhancing color fixation. Gelatin is a traditional natural adhesive mainly composed of proteins, typically sourced from animal skins or tendons. Gelatin enhances the coloring power of pigments in the conservation process. Its composition and properties make it widely used in Chinese conservation literature, and as a traditional conservation material, it has been proven to be effective.
Comparison of the color between different dying treatment methods. (a) Newly processed palm leaf pieces without inscriptions. (b) Palm leaf pieces treated with black tea dyeing (formula: 40 g black tea + 1500 ml water + a small amount of ink, boiled for 2 h). (c) Palm leaf pieces dyed with Chinese painting pigment (using pigments such as ochre, gamboge (藤黄) and Chinese indigo (花青), ink, and alum size for layer-by-layer toning). (d) Palm leaf pieces subjected to accelerated aging treatment (dry heat treatment at 120 °C for 10 days).
To mitigate any potential harm to the PLMs caused by high concentrations of alum–gelatin solution, strict control over its concentration throughout the dyeing process is essential. The application of multiple layers of pigment through repeated brushing aimed to achieve the desired dyeing effect while safeguarding the integrity of the manuscripts. After coloring with ochre and allowing it to dry, gamboge (藤黄), and Chinese indigo (花青) were applied successively, striving to achieve the same appearance as the original document. Through this process, it can not only preserve the historical authenticity of the document to the greatest extent but also ensure the natural integration of the infills with the original document in terms of visual effects and texture. Although dyeing can effectively enhance the visual consistency of the treatment results, the decision to use this method still needs to be comprehensively judged based on the specific needs of the individual object and long-term preservation goals.
2.2.2 Application of Palm Leaf Powder, Fiber Strips, and Pulp
Palm leaf pulp is formulated by blending palm leaf powder with gelatin (20 %), which provides excellent adhesion and plasticity. Compared to other materials, palm leaf pulp exhibits higher plasticity and superior adhesive properties. After the curing process, it offers robust support, particularly when repairing cracks and small areas of loss. It maintains the stability of the treated area and prevents deformation. Consequently, palm leaf pulp not only ensures the effectiveness of the conservation treatment but also enhances the durability and stability of the treated parts. The primary component of palm leaf pulp, leaf powder, is sourced from leaves identical to the original material of the palm leaf, ensuring effective compatibility with the original material. Palm leaf powder is produced by grinding blank new palm leaves and sifting them through a mesh with 60 or more openings per inch. Palm leaf fiber strips are produced using a 40-mesh screen to select fiber strips measuring 2–5 mm in length. These fiber strips possess strong and resilient qualities, providing effective physical support. In actual conservation processes, palm leaf pulp and powder are primarily used to fill small areas of loss and cracks, while palm leaf fiber strips are employed for larger areas of loss and cracks to establish a supportive framework that enhances structural stability.
2.2.3 Selection of Adhesive: Properties and Long-Term Stability
The choice of adhesives plays a critical role in the conservation of manuscripts, directly impacting the reversibility and long-term stability of the treatment. This study begins by conducting a comprehensive review of relevant literature on manuscript conservation, both domestically and internationally, categorizing commonly used adhesives into three groups:
Animal glues, such as gelatin, fish glue, and isinglass, derived from animal proteins, are known for their excellent adhesion and reversibility.
Plant-based adhesives, including starch paste, methyl cellulose, and carboxymethyl cellulose, sourced from natural plants, are environmentally friendly and biocompatible.
Synthetic adhesives, like acrylic emulsions, acrylic rubber, and Cascamite®, are characterized by high strength and durability, but their lack of reversibility requires careful consideration.
Adhesives are typically selected as either a single type or a combination of two types, such as a blend of EVA and methyl cellulose (MC), or a mix of MC and wheat starch paste. Commonly used adhesives include methyl cellulose, wheat starch paste, and fish glue (sturgeon glue). The fish glue employed possesses reversibility under specific environmental conditions. This means that in particular environments, such as high temperature and humidity, the adhesives can be safely removed, thereby ensuring the reversibility of the repair process. However, under normal storage conditions, these adhesives provide sufficient durability to ensure the long-term stability of the repaired area. The use of animal glues should be evaluated based on cultural context and material suitability. For example, the use of fish glue may be restricted in certain cases (Liu 2018).
A comparative analysis of the color and bonding strength of four adhesives – methyl cellulose, wheat starch paste, fish glue, and cowhide glue – was conducted. Each adhesive was prepared at a 20 % concentration with a curing time of 3 h and was categorized into four levels based on bonding strength: weak (+), moderate (++), strong (+++), and very strong (++++). The results, listed in Table 1, revealed that fish glue has a lighter color and superior bonding strength. Therefore, fish glue was selected, and its concentration was increased to 30 % in this study. The optimized fish glue demonstrates strong adhesion at room temperature, securely bonding conservation materials with the original. After rigorous testing in high-temperature and high-humidity conditions, the adhesive exhibits good reversibility, enhancing the flexibility of conservation operations and ensuring smooth progress in subsequent conservation or adjustment processes. This meets the stringent requirements for reversibility and long-term stability in manuscript conservation.
Performance comparison of four adhesives.
| Name | Type | Color | Strength |
|---|---|---|---|
| Methyl cellulose | Cellulose derivative | Transparent | ++ |
| Wheat starch paste | Plant paste | Milky white | + |
| Fish glue | Animal glue | Light yellow | +++ |
| Cowhide glue | Animal glue | Dark yellow | ++++ |
2.3 Conservation Strategy
The conservation of manuscripts is an intricate process that demands careful planning and execution, tailored to the unique conditions of damage and conservation objectives. The following outlines the specific conservation process:
2.3.1 Damage Classification
Accurate classification of damage is crucial prior to the conservation process, as it enables the implementation of appropriate measures tailored to the specific conditions of damage, thereby ensuring targeted and effective treatment. The types of damage can be broadly categorized into the following five categories:
Small Areas of Loss: These are areas of loss less than 4 mm2, typically caused by insect damage or long-term friction. Although small in size, they may significantly impact the overall integrity and aesthetics of the document when they are numerous, necessitating delicate infills.
Large Areas of Loss: Ranging in size from 4 mm2 to 25 mm2, these areas of loss are usually the result of more severe physical damage or biological attack. Filling large areas of loss should not only focus on filling properties but also enhance the structural stability of the treated areas.
Cracks and Tearing: Longitudinal or transverse cracks on manuscript leaves, often due to the brittleness of the material or external forces. Treatment of cracks and tears involves the use of reinforcement materials to stitch and support the damaged areas to prevent further expansion.
Severe Loss: Severe loss of the manuscript leaf area can significantly impact content, structure, and appearance. Filling in the missing areas is necessary during conservation, ensuring that the physical properties, appearance, and chemical stability of the conservation materials align with the original materials to restore the integrity and visual coherence of the document.
Fraying fibers: The pulling and loosening of fibers at the edges of manuscript leaves, commonly found in long-term exposed areas. This type of damage affects the stability of the document’s edges, requiring organization and reinforcement of fibers during conservation.
2.3.2 Cleaning and Stain Removal
During the conservation process, decontamination and cleaning are crucial in ensuring the quality and efficacy of subsequent conservation efforts. Cleaning is essential for removing accumulated dust and stains, thereby establishing a pristine foundation for repair work. It also promotes optimal adhesion of conservation materials and enhances the stability and overall integrity of the treatment. This study outlines the cleaning process in two distinct steps:
Dry Cleaning: The manuscript surface is carefully wiped with static dust removal paper to eradicate loose dust and dirt. Utilizing static electricity facilitates the absorption of contaminants, mitigating the risk of material damage from friction.
Wet Cleaning: A clean, damp soft cloth is employed for a thorough wipe-down, with a moistened cotton swab or melamine-foam sponge for localized heavy contamination. Throughout the cleaning procedure, particularly for aged and brittle manuscripts, a gentle approach is imperative to effectively eliminate contaminants while minimizing the risk of additional damage to the document material. Especially when using melamine-foam sponge for cleaning, it is necessary to test on a small area without visible marks first, and then apply it cautiously to minimize the potential impact.
2.3.3 Repair and Reinforcement
Repair and reinforcement are pivotal stages essential for reinstating the document’s structural integrity. Tailoring the conservation approach to the specific type of damage is paramount to ensure that the treated manuscript regains its visual balance and physical stability. This study advocates the following techniques for repair and reinforcement:
Small Areas of Loss: A blend of palm leaf pulp and powder proves effective. The fluidity and adhesion of palm leaf pulp enables it to seep into minute crevices, while the finely granulated palm leaf powder seamlessly integrates with the original material, thereby restoring the document’s integrity.
Large Areas of Loss: Use palm leaf fiber strips in conjunction with its pulp and powder for filling in large areas of loss. The fiber strips establish a foundational support structure, strengthening the repair area. Subsequently, the application of palm leaf pulp and powder results in a texture akin to the original material after drying.
Cracks and Tearing: Employ palm leaf pulp and powder to fill small gaps, while larger crevices necessitate an initial layer of palm leaf fiber strips followed by the application of palm leaf pulp and powder to restore mechanical strength.
Severe Loss: Fill in pieces of palm leaf that closely resemble the original in texture, thickness, and color as inserts. After dyeing, these inserts seamlessly adjust to the surrounding material, ensuring visual cohesion.
Fraying fibers: After aligning loose fibers, apply an appropriate adhesive to fix them. Subsequently, fill the interstices between fibers with palm leaf powder to fortify the edges. This comprehensive approach not only restores stability and functionality to the edges but also ensures a seamless integration with the overall document, both in appearance and physical properties.
2.3.4 Flattening Treatment
Upon completion of the repair process, it is imperative to conduct a flattening treatment on the manuscript to reinstate its original smoothness and shape. The method of dampening is typically adjusted based on the smoothness and damage of the palm leaf manuscript, with the precondition that the ink is not easily blurred. Lightly curled palm-leaf manuscripts with stable ink are placed on blotting paper and lightly sprayed with a small amount of water. Water vapor diffusion is used to moisten the surface of the palm leaf manuscript, avoiding excessive wetting or fiber expansion. Subsequently, the palm leaf manuscript is sandwiched between two pressing boards, and a suitable amount of weight is evenly placed on top to apply pressure, ensuring it dries flat. Once the palm leaf manuscript is completely dry, the weights and blotting paper are removed. For palm-leaf manuscripts with more severe curling, the humidity is adjusted, and more detailed treatment methods are adopted as needed to ensure the stability and safety of the repair effect.
This flattening procedure typically involves moistening the manuscript and gently pressing it, utilizing moisture and consistent pressure to gradually flatten the document during the drying phase. The operation is outlined below: begin by positioning the manuscript on an absorbent paper, lightly spraying a small quantity of water onto the paper’s surface. Allow the moisture to diffuse and moisten the manuscript’s surface, taking care to avoid excessive dampness or fiber expansion. Subsequently, sandwich the manuscript between two pressing boards and apply even weights on top to ensure uniform pressure, facilitating its flat drying. Once the manuscript is thoroughly dry, remove the weights and absorbent paper to reveal its restored smooth state.
2.3.5 Restoring the Binding and Protective Housing
Restoring the binding is a crucial step in ensuring the manuscript’s functionality. It is essential to utilize methods and materials that align with the original binding to uphold the coherence and structural integrity of the document. When carrying out the binding process, it is advisable to opt for traditional brown thread or the same material used in the original binding to maintain consistency in both appearance and texture with the restored manuscript. To ensure long-term preservation, proper storage methods and regular inspections are as crucial as the conservation treatment itself. Specific measures include the following aspects:
Protective storage: The restored PLM should be housed in acid-free cardboard boxes, cloth bags, or specialized protective boxes. Storage materials should not be in contact with materials containing harmful components to prevent chemical reactions that could affect the PLMs. In this study, acid-free polyester film, acid-free boxes, and acid-free boards were employed to store the PLMs, effectively isolating them from environmental humidity and acidic substances (Lin, Zhou, and Zhang 2012) (Figure 3).
Temperature and humidity control: Given the high moisture absorption of PLM materials, both high and low temperatures and humidity levels can cause deformation, cracking, or mold growth, thereby affecting their long-term preservation. The storage environment should be maintained within a constant temperature range (recommended between 18 °C and 22 °C) and humidity range (recommended between 45 % and 60 %) to ensure the stability of the PLMs.
Light and UV control: PLMs are highly sensitive to ultraviolet radiation, and prolonged exposure to UV radiation can cause material aging, fading, and embrittlement. Therefore, the treated manuscripts should be stored in an environment that avoids direct ultraviolet radiation. If necessary, UV filters should be used for effective isolation to reduce UV damage to PLMs.
Air quality and insect prevention measures: Treated PLMs should be stored in a pollution-free and insect-free environment. To prevent insect infestation and mold growth, natural insect repellents can be used regularly for protection. The storage environment should maintain good ventilation to avoid moisture accumulation.
Enclosures for PLMs’ fragments. (a) For display (b) For storage.
In addition, regular inspections are a vital measure to ensure the long-term preservation of PLMs. It is recommended to conduct a comprehensive inspection at least once a year, including checking the structural integrity of the storage site, changes in material, color stability, and whether new damage or deformations have occurred. If minor damage or unsatisfactory conservation results are identified, necessary interventions should be carried out promptly.
Based on the inspection results, adjustments can be made to factors such as temperature, humidity, and light exposure in the storage environment to ensure they always meet the optimal requirements for PLM preservation. Additionally, regular inspections should also evaluate the effectiveness of the conservation process itself and adjust or optimize conservation methods as needed.
3 Case Studies
This paper empirically implements the proposed methods in specific conservation cases to validate their effectiveness and practicality. Through these case studies, a comprehensive overview is presented regarding the selection of materials, conservation techniques and results for various types of damage encountered during the conservation of PLMs. During the conservation process, steps such as repairing damage, shaping, pressing and fixing, drying and curing are undertaken to prevent further damage and restore the integrity of the document. The primary objective of shaping the infill material is to ensure that the infill fits the area of loss, achieving a tight bond with the original material. Fine-tipped tweezers, scalpels, and other tools are utilized to meticulously shape the infill material, making the seams natural and the surface smooth, thereby ensuring the structural integrity and visual effect of the infill area. The pressing and fixing step aims to ensure that the PLMs are flat. A uniform pressure of 1–5 kg is applied, with the pressure adjusted based on the original strength of the PLM. Pressing not only promotes the tight fit of the repair material but also effectively stabilizes the repair area, preventing material displacement or loosening during the conservation process. It is important to note that anti-adhesive material, such as sheets of Hollytex©, are used to ensure that the infill material does not stick to the pressing surface. The purpose of drying is to ensure the solidification of the adhesive and PLM filler, forming a stable support structure. During this process, the material needs to be dried for 3–24 h to allow the adhesive to cure completely, thereby ensuring the strength of the repair area.
3.1 Repair of Losses
The primary challenge in filling areas of loss is the need to reinforce the strength and structural integrity of the material while preserving the authentic appearance of the PLM. To address this challenge, the present study introduces an innovative treatment approach that strategically employs palm-leaf pulp, fiber strips, and powder for layered filling and reshaping of the areas of loss, resulting in significant improvements. Subsequent sections will provide a detailed breakdown of the procedures and outcomes for both small and large areas of loss, demonstrating the efficacy of this method in practice.
3.1.1 Small Areas of Loss
For filling small areas of loss, a filling and shaping technique was employed utilizing palm-leaf pulp, with the detailed steps outlined below:
Preparation of palm-leaf pulp: Palm leave powder was prepared by crushing and sieving palm leaves. The powder was then mixed with a 20 % gelatin solution in a mass ratio of 1:4 to 1:4.5 to form a uniform palm-leaf pulp.
Filling with palm-leaf pulp: A silicone brush was used to evenly apply the palm-leaf pulp to the area of loss, ensuring coverage without excessive thickness.
Removal of excess pulp: Prior to the palm-leaf pulp solidifying, any surplus material was carefully removed to maintain a consistent thickness in the repair area, either even with or slightly lower than the surrounding area.
Application of palm-leaf powder: A layer of palm-leaf powder was sprinkled over the repair to prevent adhesion, gently pressing it down with a tool.
Small areas of loss on the PLMs were effectively filled with this method. The results shown in Figure 4a and b illustrate that the integrity of the PLMs has been significantly enhanced and that the further expansion of the small loss will be inhibited.
Comparison of small areas of loss (a) before and (b) after treatment.
3.1.2 Filling Large Areas of Loss
The following steps demonstrate the filling and reinforcement approach for large areas of loss:
Application of adhesive: fish glue (30 %) is applied to the edges of the large areas of loss to establish a strong foundation for subsequent infill materials.
Filling with palm-leaf fiber strips: Palm-leaf fiber strips are carefully inserted into the area of loss, ensuring they are closely and evenly distributed to create a stable base for the following layers.
Filling with palm-leaf pulp: Palm-leaf pulp is evenly spread over the fiber strips to further reinforce and fill the area of loss.
Filling with palm-leaf powder: Palm-leaf powder is applied to the surface of the area of loss, ensuring thorough integration with the fiber strips and palm-leaf pulp to establish a sturdy structural support.
Upon comparing the images before and after treatment (Figure 5), it is evident that using this innovative technique, missing areas could be successfully filled in, seamlessly integrating the infills with the original manuscript. Infills exhibit no visible irregularities in thickness, demonstrating the precision of the conservation process. This method not only preserves the integrity of the PLM but also significantly enhances its structural stability, ensuring its longevity and continued preservation.
Comparison of large areas of loss (a), (c) before and (b), (d) after repair (without toning).
For the infill of missing areas, two distinct materials and methods were employed: one involves dyeing to simulate the aged appearance of the historical PLM (Figure 4), while the other employs a “non-aging” treatment based on the principle of artifact recognizability (Figure 5). A comparison of the before and after photos reveals that the new repair method effectively fills the missing areas, with the infilled sections naturally blending with the original piece, exhibiting no noticeable uneven thickness. To further evaluate the treatment result, the thickness and color of the infilled area were measured. Experimental results indicate that the thickness of the infilled area does not differ by more than 0.5 mm from the original document, and the total color difference does not exceed ΔE of 2. Specifically, ΔE values between 0 and 0.25 indicate very small or no color difference, having the ideal match; ΔE values between 0.25 and 0.5 indicate minor color differences, falling within an acceptable range; ΔE values between 0.5 and 1.0 indicate minor to moderate color differences, acceptable in some applications; ΔE values between 1.0 and 2.0 indicate moderate color differences, suitable only for specific applications.
3.2 Mending of Cracks and Tears
Mending cracks in PLMs poses a significant challenge, as it requires restoring mechanical strength to prevent cracks from opening further while preserving the original structure and appearance. Minimizing visible treatment traces is essential to maintain authenticity. The method of mending cracks depends on the severity of the damage. Minor cracks can be effectively treated through filling and shaping with palm-leaf pulp, whereas larger cracks necessitate stratified filling and reinforcement similar to infill methods. Precision and material selection are critical during crack repair to ensure that the filling material matches the manuscript’s texture and color, thereby enhancing structural stability.
Figure 6a shows a PLM with a large crack. After repair, the crack area appears smooth, with filling material matching the manuscript’s texture and color (Figure 6b). The treatment significantly enhances structural stability, effectively preventing further cracking. The treated PLM retains its historical appearance and is better prepared for long-term preservation.
Comparison of crack (a) before and (b) after infilling (without toning).
3.3 Filling in Large Areas of Loss
The primary challenge with large areas of loss in PLM is to restore the integrity of the manuscript while ensuring that the infill material matches the texture, thickness, and color of the original. In the following case studies, both undyed and newly processed dyed palm leaves were employed. The selection of the appropriate palm-leaf infill is based on the manuscript’s specific damage, treatment objectives, and display requirements. Through splicing and filling, the infill achieves both structural reinforcement and aesthetic enhancement. The detailed steps are as follows:
First, a new, blank palm leaf with a texture and thickness similar to the original was selected for the infill. When shaping the infill, consistent grain direction should be maintained, the shape of the infill should adjust exactly to the area of loss, ensuring a tight fit. After applying adhesive evenly along the damage’s edge, the trimmed palm-leaf infill was spliced, ensuring a seamless bond with the surrounding material. Any gaps at the seam were filled with palm-leaf pulp. This process mirrors crack repair, with a focus on achieving a natural transition between the infill and the original, avoiding excess material buildup or surface irregularities. Throughout the repair process, pressing, drying, and curing operations are crucial to securely bond the infill with the original. During the final inspection and adjustment, it should be ensured that the treated area closely matches the texture and color of the PLM, with discreet intervention traces, ensuring it possesses both high mechanical strength and visual harmony.
The area filled in with undyed new palm leaves maintains the original natural color of the palm leaf (Figures 5 and 6). In contrast, the dyed palm leaves are more closely matched in color to the original, both methods effectively restore the integrity of the palm-leaf manuscript (Figure 7). Figure 7a illustrates a case of rodent damage. After repair, the integrity of the PLM was enhanced, as shown in Figure 7b. Figure 7c shows a PLM that is only half its original size, likely due to improper storage and subsequent loss. By employing the aforementioned infilling method, its original size was restored. The greatest advantage of this repair method is that it standardizes the size of the repaired PLMs, making them much easier to store.
Comparison of large area loss (a), (c) before and (b), (d) after infills with pieces of dyed palm leaf.
3.4 Treatment of Fraying Fibers
The key to addressing fraying fibers lies in restoring the smoothness of the fibers while ensuring that the treated area retains stability. When treating fraying fibers in PLMs, the initial step involves combing and arranging the damaged fraying fibers to ensure they are smooth and flat. If the fibers are curled or twisted, they can be slightly moistened and then quickly dried to help restore their natural shape.
During the mending process, an appropriate amount of adhesive should be applied to ensure even distribution across the fiber layers. This allows the adhesive to effectively penetrate the interior of the fibers, thereby stabilizing the fiber structure. Any excess adhesive should be promptly removed to avoid affecting the visual appearance after treatment. Palm-leaf powder is then used to fill the fraying area, adjusting the loose fibers to facilitate further treatment. The standard procedure for loss repair should be followed to ensure the integrity of the result.
Figures 8a and c both show fraying fibers at the edges of the PLM before treatment; Figures 8b and d shows treatment results. The treated PLMs are smooth and flat, with inconspicuous traces of intervention. The intervention had not changed the visual appearance to the original, thus fully preserving the historical character of the PLM.
Comparison of fraying area (a), (c) before and (b), (d) after repair.
4 Conclusion and Prospects
This work presents a conservation strategy that is compatible with the structure and appearance of PLMs. It systematically introduces repair methods, material selection, and treatment results for various types of mechanical damage. The steps include damage classification, cleaning and decontamination, reinforcement and repair, flattening, restoration of the binding, and protective housing. Infills of areas of loss not only closely match the thickness and color of the original material but also adheres to fundamental principles of cultural heritage preservation. This effectively restores the integrity of the PLMs to ensure their continued preservation and use.
Although this study has made progress in PLM conservation, there is still potential for further investigations. Firstly, due to the complexity of damage to PLMs, this study has only explored selected damage types and has not comprehensively covered all possible damage phenomena. Therefore, further research is needed in the future to expand the scope of study and explore other types of damage. Secondly, conservation measures have not been systematically tested and verified in the laboratory, lacking scientific data to support long-term stability. Particularly, the aging performance of dyed palm leaves requires more testing through accelerated aging experiments such as exposure to light and high humidity conditions. Additionally, further optimization of conservation materials remains a key research direction, particularly the curing time and bonding strength of adhesives warrant in-depth investigation.
For the long-term preservation of manuscripts, it is essential to fully understand the feasibility, applicability, and potential risks of each technique and material to clarify which methods can be applied in practice and which are still in the experimental stage. This will help reduce uncertainties and risks that may arise during the conservation process, ensuring that the adopted techniques, materials, and processes do not have adverse effects on historical manuscripts. The goal of an interventive treatment is to restore the visual balance of manuscripts, making them readable and ensuring their long-term preservation.
In conclusion, the conservation of manuscripts still faces many challenges, and future research will focus on optimizing conservation techniques and materials, verifying their long-term stability, and promoting the standardization and universality of conservation methods. It is hoped that the methods and cases proposed in this article can provide a theoretical basis and practical references for the practice and future research of preserving manuscripts.
Funding source: Palm Leaf Manuscript Conservation Foundation of Yunnan Academician Workstation
Award Identifier / Grant number: YAW23002
Funding source: National Ethnic Affairs Commission Ethnic Research Project of China
Award Identifier / Grant number: 2024-GMI-036
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Research funding: This research was supported by the Palm Leaf Manuscript Conservation Foundation of Yunnan Academician Workstation (YAW23002) and National Ethnic Affairs Commission Ethnic Research Project of China (2024-GMI-036).
References
Agrawal, O. P. 1984. Conservation of Manuscripts and Paintings of South-East Asia. London: Butterworth-Heinemann.Search in Google Scholar
Crowley, A. S. 1969. “Repair and Conservation of Palm-Leaf Manuscripts.” Restaurator. International Journal for the Preservation of Library and Archival Material 1: 105–14, https://doi.org/10.1515/rest.1970.1.2.105.Search in Google Scholar
Gupta, C. B. 1974. Preservation of Palm Leaf Manuscripts. New Delhi: Conservation of Cultural Property in India VII.Search in Google Scholar
Harinarayana, N. 1995. “Techniques of Conservation of Palm Leaf Manuscripts: Ancient and Modern.” In Palm Leaf and Other Manuscripts, 261–74. Madras: Institute of Asian Studies.Search in Google Scholar
Huang, X., and M. Zhang. 2020. “The Risk Assessment and Treatment in the Process of Manual Restoration of Palm Leaf Manuscripts.” Journal of Academic Library 38 (4): 106–11.Search in Google Scholar
Jacobs, D. 2010. Workshop Notes of the Conservation and Stabilization of Palm Leaf Manuscripts, 27–8. Cambridge: South Asia Library Group, Newsletter.Search in Google Scholar
Joshi, B. R. 1989. “Preservation of Palm Leaf Manuscripts.” Conservation of Cultural Property 120–7.Search in Google Scholar
Jurkiewicz, I. 2017. Magic in Conservation–Using Leaf-Casting on Paper and Palm Leaves [Online]. London: Collection Care Blog, The British Library.Search in Google Scholar
Lin, M., Y. Zhou, and J. Zhang. 2012. Preservation and Conservation of Library and Archival Materials. Guangzhou: Sun Yat-Sen University Press.Search in Google Scholar
Liu, J., and Y. Huang. 2018. “The Impact of Certain Materials on the Long-Term Preservation of Ancient Books: Water, Cardboard, and Wood.” Research on the Conservation of Ancient Books 156–71, https://doi.org/10.1186/s11671-018-2574-6.Search in Google Scholar
Lyu, X., and M. Zhang. 2020. “An Overview of Conservation and Restoration of Palm Leaf Manuscripts.” Journal of National Museum of China (8): 147–60.Search in Google Scholar
Nichols, K. 2004. “An Alternative Approach to Loss Compensation in Palm Leaf Manuscripts.” Paper Conservator 28 (1): 105–9, https://doi.org/10.1080/03094227.2004.9638646.Search in Google Scholar
Poirier, J. 2020. Delaminating and Fraying Fibres: Developing an Advanced Treatment Approach for the Conservation of a 12th Century Palm Leaf Manuscript [Online]. Dublin: Chester Beatty, Dublin Castle.Search in Google Scholar
Sah, A. 2002. “Palm Leaf Manuscripts of the World: Material, Technology and Conservation.” Studies in Conservation 47 (Suppl. 1): 15–24, https://doi.org/10.1179/sic.2002.47.supplement-1.15.Search in Google Scholar
Sharma, D., M. R. Singh, and B. Dighe. 2018. “Chromatographic Study on Traditional Natural Preservatives Used for Palm Leaf Manuscripts in India.” Restaurator. International Journal for the Preservation of Library and Archival Material 39 (4): 249–64. https://doi.org/10.1515/res-2018-0005.Search in Google Scholar
Takagi, N., Y. Chudo, R. Maeda, and Y. Saito. 2006. “Preservation Cooperation in Nepal: From Training to Conservation and Digitization of Rolled Palm Leaf Manuscripts.” In Preservation and Conservation in Asia in Pre-Conference of WLIC. Tokyo: National Diet Library.Search in Google Scholar
Wiland, J., R. Brown, L. Fuller, L. Havelock, J. Johnson, D. Kenn, P. Kralka, M. Muzart, J. Pollard, and J. Snowdon. 2022. “A Literature Review of Palm Leaf Manuscript Conservation–Part 1: A Historic Overview, Leaf Preparation, Materials and Media, Palm Leaf Manuscripts at the British Library and the Common Types of Damage.” Journal of the Institute of Conservation 45 (3): 236–59, https://doi.org/10.1080/19455224.2022.2115093.Search in Google Scholar
Wiland, J., R. Brown, L. Fuller, L. Havelock, J. Johnson, D. Kenn, P. Kralka, M. Muzart, J. Pollard, and J. Snowdon. 2023. “A Literature Review of Palm Leaf Manuscript Conservation–Part 2: Historic and Current Conservation Treatments, Boxing and Storage, Religious and Ethical Issues, Recommendations for Best Practice.” Journal of the Institute of Conservation 46 (1): 64–91, https://doi.org/10.1080/19455224.2023.2167095.Search in Google Scholar
Yu, D., X. Li, S. Sun, H. Guo, H. Luo, J. Zhu, Li. Li, S. Wang, and L. Han. 2024. “The Effect of Traditional Processing Craft on the Hygroscopicity of Palm Leaf Manuscripts.” Heritage Science 12 (1): 280, https://doi.org/10.1186/s40494-024-01402-2.Search in Google Scholar
Zhang, M., X. Song, X. Lv, J. Wang, and Zla-Sgron. 2022a. “Diagnosis of Main Deterioration of the Palm Leaf Manuscripts in Tibet and Analysis of the Key Techniques for Restoration.” China Tibetology (4): 165–78.Search in Google Scholar
Zhang, M., X. Song, J. Wang, and X. Lyu. 2022b. “Preservation Characteristics and Restoration Core Technology of Palm Leaf Manuscripts in Potala Palace.” Archival Science 22 (4): 501–19. https://doi.org/10.1007/s10502-021-09383-y.Search in Google Scholar
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Articles in the same Issue
- Frontmatter
- Original Works
- Preserving the Scientific Legacy: An Integrated Pest Management Approach from a Heritage Astronomy Library
- Testing the Effectiveness of Selected Flame Retardants for Archival Cardboard Using a Medium-Scale Fire Test
- Conservation Strategies for Palm-Leaf Manuscripts from Yunnan, China
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Articles in the same Issue
- Frontmatter
- Original Works
- Preserving the Scientific Legacy: An Integrated Pest Management Approach from a Heritage Astronomy Library
- Testing the Effectiveness of Selected Flame Retardants for Archival Cardboard Using a Medium-Scale Fire Test
- Conservation Strategies for Palm-Leaf Manuscripts from Yunnan, China
- Traditional Ways of Caring for Historical Manuscripts in Lombok (Indonesia)
