Multidimensional exploration in bronze restorative conservation under the synergistic perspective of chemistry and art: a systematic review

Abstract

This study centers on the symbiotic integration of art and chemistry in the conservation of bronze artifacts. Focusing on chemical analysis, cleaning, corrosion protection, and sealing, it aims to balance scientific stability with historical authenticity. Using Ming Dynasty figurines and Egyptian arrowheads as case studies, it highlights interdisciplinary collaboration. The research also envisions intelligent restoration and digital monitoring technologies to enhance the precision, sustainability, and effectiveness of cultural heritage preservation.

Introduction

As an important material witness to the process of human civilization, the conservation and restoration of bronzes have always faced the double test of historical authenticity and technical feasibility. The promulgation of the Convention Concerning the Protection of the World Cultural and Natural Heritage in 1972 not only established a global system for the protection of cultural heritage but also provided an ethical framework for the practice of bronze restoration through the establishment of the principles of authenticity and integrity¹, i.e., any intervention must respect the integrity of the original material composition of the artifacts and the artistic information. This concept is particularly evident in the Shang and Zhou bronzes²: the beauty of the Taotie motif highlights the sanctity of the ritual system, the lost wax casting of the cloud and thunder motif implies the philosophical balance of Yin and Yang, and the Black Lacquered Ancient leather shell formed over thousands of years condenses the aesthetic dimension given by time. These visual symbols carrying the code of civilization often face the crisis of disintegration after excavation due to layer corrosion caused by chlorine ion penetration³, potential difference corrosion of copper-tin-lead alloys⁴, and bronze disease triggered by fluctuations in temperature and humidity⁵.

To respond effectively to these problems, the application of chemical technologies is particularly important, providing critical support for the preservation of this precious cultural heritage. In this field, chemical technologies demonstrate their unique disciplinary strengths. For instance, X-ray fluorescence spectroscopy (XRF) can go through rust and accurately find out what alloying elements are on the surface of bronzes⁴; benzotriazole (BTA) molecules can create a protective layer on bronzes by connecting with the copper ions⁶; and Nano-silica (SiO₂) sealants can enhance the corrosion resistance of coatings and possess strong hydrophobic properties, effectively protecting bronze from environmental damage⁷. However, with the advancement of technology, the controversy of whether the intervention is excessive and whether it affects the historical authenticity in the process of cultural relics restoration has gradually come to the fore. For example, during the restoration of Dunhuang murals, traditional LIBS technology has certain limitations in the in-situ analysis of murals: it cannot monitor the damage to the mural in real time, and it is also prone to causing significant damage to the mural during the detection process⁸. Therefore, when utilizing advanced technologies for cultural heritage conservation, we need to carefully weigh the relationship between the application of technology and the preservation of cultural values.

At present, the technical difficulties of chemical technology restoration and protection are mainly concentrated in three aspects: The first aspect pertains to the relevance and controllability of restoration methods. Although research on bronze materials, corrosion types, and burial environments has been more in-depth, the long-term impact of different restoration methods still lacks systematic assessment⁹. Secondly, the stability and safety of corrosion inhibition and sealing materials remain unascertained. Some traditional corrosion inhibitors (e.g., BTA) can break down when exposed to UV rays and may pose safety risks if used for a long time¹⁰; on the other hand, bio-based materials (e.g., chitosan) are better for the environment but can be broken down by microbes, which reduces their protective strength¹¹. How to develop an efficient, environmentally friendly, durable new corrosion inhibition system is still a key issue. Thirdly, the integration of restoration and aesthetics remains a crucial issue. Existing chemical restoration methods focus primarily on the structural stability of the bronze traces of time. For example, corrosion inhibitors, protective coatings, and cleaning and rust removal techniques are used to enhance the physical stability and long-term preservation of bronze¹². However, these techniques are more focused on preventing physical degradation, the pulp layer, decorative weathering, and other aesthetic characteristics, often lacking precise regulation¹³. How to optimize the restoration technology without destroying the historical authenticity of the premise so that it can meet the needs of stabilize the physical structure of bronze and extend its lifespan, but also to maintain the artistic integrity of cultural relics, is still an important issue that needs to be resolved.

This study adopts a multidisciplinary approach integrating artistry and chemistry to optimize bronze restoration by leveraging modern material science while respecting historical aesthetics. The goal is to restore bronzes that faithfully retain their original artistic style and embody the cultural spirit of ancient craftsmanship, thereby providing novel perspectives and methodologies for sustainable cultural heritage conservation.

Methods

Analysis of the historical and cultural value of bronzes and their corrosion mechanisms in the burial environment

Bronze not only carries the historical memory of ancient civilizations but also bears witness to the impact of time and the environment on its form and structure. The history and legacy of bronze represent a dynamic process, which depends not only on its production and usage but also on the changes it undergoes in its burial environment¹⁴. From a taphonomic perspective^15,16, this process can be thoroughly understood by examining the various transformations bronze experiences during burial. Surface corrosion, patina formation, and microstructural changes in bronze not only reflect the conditions of the burial environment but also document the combined effects of natural and human factors over a long historical period.

In this process, the study of site formation processes^15,17 – a theoretical framework that examines how cultural relics are affected by natural and human factors during burial – reveals the preservation conditions of bronze under different environmental settings. The burial environment of bronze, including soil composition, humidity, temperature, and other factors, determines the type and degree of corrosion it undergoes. Taking chlorides as an example¹⁸, bronze is prone to corrosion by products such as copper(I) chloride (CuCl) in saline-alkaline soils, which leads to “bronze disease”. This corrosion not only damages the structure of the bronze but also affects its appearance. Microbial activity may also accelerate the corrosion process, especially in humid or organic-rich environments. These factors play a driving role in the degradation of bronze.

By understanding the site formation processes that bronze undergoes during burial, we can gain clearer insight into the challenges of post-excavation restoration and the development of effective conservation strategies¹⁹. The historical value of bronze lies not only in its cultural and artistic significance but also in how it has endured environmental changes and corrosion over long periods – offering critical clues for future restoration and preservation efforts. Therefore, the inheritance and conservation of bronze are not merely matters of restoration techniques, but also scientific responses to, and understandings of, the processes it has undergone under specific historical and environmental conditions.

Historical inheritance and cultural meaning of bronzes. The Xia Dynasty (ca. 21st century BC-16th century BC) is considered the beginning of Chinese bronze civilization^20,21. Due to the establishment of the ritual system, a part of the bronzes began to be used as the ritual vessels of the ruling class, and they were closely integrated with the kingship, ancestor worship, and the sacrificial system, which formed a system of political symbols that hid rites and rituals in the vessels. The heyday was concentrated in the Shang and Zhou Dynasties (about 1600BC–25BC), and the bronze casting technology reached its peak in the late Shang Dynasty, where inscriptions were realized through the casting process of the embedding method, which made the bronzes serve the dual functions of historical records and ritual symbols²². The application of the lost wax method promotes the three-dimensional innovation of the bronze decoration system, but its function is still centered on the ritual system; from the Xia, Shang and Zhou to the Qin and Han Dynasties, the bronzes continued the ritual, military and ceremonial functions, and at the same time, gradually derived from the expression of the aesthetics of life. The trinity of material, technology and decoration in the casting of ritual objects not only provides a technical paradigm for the history of arts and crafts but also transmits philosophical ideas through the symbolic system of object – decoration – inscription²³.

In other parts of the world, bronzes are equally historically and culturally important. In ancient Egypt, bronzes were mainly used to make tools, weapons and religious artifacts, such as the Astarte Throne Bronze in the temple of Bostan esh-Sheikh, whose totem blends Pharaoh’s authority with polytheistic beliefs, reflecting the religious beliefs and the cult of kingship in ancient Egypt²⁴. In ancient Greece and Rome, bronze was mainly used to make sculptures, weapons, and everyday objects. Ancient Greece bronze sculptures are known for expressing the emotion and dynamism of their figures, such as the Riace warriors²⁵. In the Roman period, bronze was more utilitarian, and it was widely used to make weapons, tools, and architectural decorations²⁶. In the Indus Valley Civilization, bronzes were mainly used to make tools, weapons, and decorations, and the style was simpler, often dominated by geometric decorations, reflecting the pragmatic tendencies of society at that time²⁷.

Bronzes are not only outstanding representatives of ancient technology but also symbols of culture, religion and politics, and the formation mechanism of their corrosion products (e.g., Cu₂O, SnO₂) reveals the interaction between environment and technology. As a carrier of historical information, the inscriptions, decorations and shapes on bronzes provide valuable information for the study of ancient societies; as masterpieces of art, they demonstrate the superior skills and unique aesthetics of ancient craftsmen; and as a link to cultural inheritance, bronzes connect modern people with ancient civilizations, enabling us to feel the continuity of history and cultural diversity.

The impact of the archaeological environment on bronzes. Bronze cultural relics are mostly buried in the ground, where minerals, organic matter, moisture, microorganisms, and other components of the soil will cause metal corrosion²⁸. The chemical environment of different soil types directly determines the corrosion form and products of bronze artifacts^29,30, and the specific effects are detailed in Table 1. According to site formation processes, the preservation state of bronzes is closely related to their burial environment. Factors such as soil composition, humidity, temperature, and burial depth directly determine the type and degree of corrosion of bronze^31,32. Different geological environments and burial conditions lead to different types of corrosion³³, which jeopardizes the integrity of the bronzes and poses unique challenges for restorative conservation. By analyzing the excavation environment in detail, the specific mechanisms of bronze corrosion can be revealed, thus providing a solid scientific basis for restoration and conservation work¹⁵. Therefore, an in-depth study of the burial environment of the bronzes from a taphonomic perspective is essential for the development of effective restorative conservation strategies to ensure the long-lasting preservation of this precious cultural heritage.

Table 1 Effect of different soil types on the corrosion mechanism of bronzes

Bronzes from different regions undergo different corrosion processes in the buried environment. Chinese bronzes are often buried in environments rich in chlorides, which can easily induce bronze disease. Cuprous chloride (CuCl) gradually changes into copper green Cu₂(OH)₃Cl when it’s wet, causing the surface to look chalky and spread out, which makes the artifacts much weaker, as shown in Fig. 1. For instance, in the Eastern Han Hollow Dragon Pattern Bronze Furnace at the Juye County Museum in Shandong Province, some artifacts have developed a serious chalky surface because of high humidity and chlorides, and they need special treatment to stop the rust from getting worse³⁴. In contrast, bronze buried in low-oxygen environments often forms a protective layer of copper oxide (Cu₂O) on its surface, which can help prevent further oxidation to some extent³⁵. However, in sulfur-rich or acidic environments, bronzes are prone to pitting, forming localized corrosion holes³⁶, as shown in Fig. 2. For instance, after long-term burial, ancient Greece and Rome bronze helmets exhibited intense pitting corrosion on their surfaces. Such corrosion was caused by microbial activities or acidic chemicals in the soil, which led to the localized dissolution of the metal and the destruction of the original structure.

Fig. 1: Micromorphology of open “powdery rust”.

a spherical “powdery rust”. b diffuse “powdery rust”³⁸.

Fig. 2: Shows the surfaces of ancient Greek and Roman bronze helmets with intense pitting corrosion after long-term burial in sulfur-rich or acidic environments.

a–f Images of representative surface corrosion present on helmets as grouped³⁶.

Humidity and water are the key environmental factors that induce bronze corrosion. The temperature, humidity, oxygen content, chloride ions and pH value of the environment in which the bronzes are located are the main factors influencing the appearance of the bronze disease³⁷. In the relative humidity of more than 75% of the environment, cuprous chloride (CuCl) is easy to hydrolyze to generate unstable corrosion products, resulting in the surface layer of chalking and flaking, seriously damaging the structure of cultural relics^38,39,40. The corrosion product layer on bronzes exposed to high humidity for a long time is usually thicker, which makes the surface structure fragile and increases the difficulty of restoration after excavation. In very dry environments with relative humidity below 30%, although the risk of bronze disease is significantly reduced, some corrosion products may undergo dehydration, which could lead to increased surface fragility and a tendency for powdering or delamination^40,41,42. Oudbashi, O.⁴³selected bronze collections from the Elam site (Haft Tappeh) in southwestern Iran and the Iron Age site (Sangtarashan) in western Iran, respectively, to analyze the soil moisture content at the burial site (Fig. 3). The Haft Tappeh site was found to have a high soil moisture content and high chlorine contamination, about 75% of the excavated artifacts were severely corroded and generally affected by bronze disease. The bronzes at Sangtarashan, due to the low water content and low chloride content of the soil, show only minor corrosion, with a stable green patina on the surface.

Fig. 3: Displays bronze artifacts from the Haft Tappeh site (with high soil moisture and severe corrosion) and the Sangtarashan site (with low soil moisture and minor corrosion) in Iran, illustrating the impact of soil moisture on bronze corrosion.

a Some bronze objects belonging to the Haft Tappeh collection. The objects are suffering from bronze disease, and pale green powdery corrosion products are visible on their surfaces. b Bronze object from the Sangtarashan collection with smooth noble patina and retained details on their surface⁵³.

The restorative conservation of bronze is influenced not only by its burial environment but also by the conditions under which it is stored and displayed after excavation⁴⁴. As metal artifacts, bronze items are highly susceptible to damage from fluctuations in temperature and humidity, harmful airborne substances, and climate changes⁴⁴. Without effective monitoring of these environmental factors, the stability of the patina and oxide layers on the surface of bronze cannot be maintained, and the outcomes of restoration efforts may be compromised by subsequent environmental changes⁴⁵.

First, fluctuations in temperature and humidity have a direct impact on the corrosion of bronze⁴⁶. When humidity is excessively high, chlorides on the surface of bronze react with copper to form cuprous chloride, which can trigger “bronze disease”^5,46. Conversely, extremely low humidity or elevated temperatures can cause the oxide layer on the surface of bronze to peel off or crack, and in severe cases, lead to irreversible changes in its surface structure⁴⁶. Without an effective environmental control system, bronze cannot maintain a stable post-restoration condition, ultimately compromising its cultural and artistic value.

In addition, the accumulation of harmful gases in the air can have a severe impact on bronze⁴⁷. When bronze is stored in environments containing high concentrations of pollutants – such as acetic acid (CH₃COOH, ACOH), formic acid (HCOOH), formaldehyde (HCHO), and acetaldehyde (CH₃CHO) – these substances can chemically interact with the artifact’s surface, producing corrosive compounds that accelerate its deterioration⁴⁷. This problem is particularly acute when the protective layer applied after restoration is inadequately preserved, as airborne pollutants can further intensify corrosion processes, leaving the artifact persistently exposed to a chemically aggressive environment without sufficient protection.

With the intensification of climate change, rising global temperatures have resulted in increasingly frequent extreme weather events⁴⁸. These climatic shifts cause sharp fluctuations in temperature and humidity, undermining the stability of storage environments for bronze. An interdisciplinary study led by the Swedish National Heritage Board (1994-2001) systematically analyzed 3200 prehistoric bronze artifacts from Sweden and Norway, revealing the direct impact of climate change-related environmental factors on bronze corrosion⁴⁹. The study focused on three regions with markedly different soil conditions – Bohuslän, Uppland, and Gotland – and compared the preservation states of bronze excavated from various archaeological periods. The findings indicated that the combined effects of soil acidification, fluctuations in temperature and humidity, and the deposition of pollutants contributed to the deterioration of the patina and oxide layers on the surface of the bronzes. These results demonstrate that even environments historically regarded as stable may, due to climate-induced changes in soil and atmospheric conditions, gradually become high-risk zones for bronze corrosion, thereby posing a long-term threat to the stability of restored artifacts⁴⁹. Therefore, the future of restorative conservation for bronze should shift from an emphasis on reactive restoration toward a more preventive and proactive approach⁵⁰.

In summary, the intricate interplay between the historical-cultural value of bronzes and their corrosion processes necessitates a multidisciplinary approach combining taphonomic, materials science, and environmental chemistry. Understanding corrosion mechanisms within diverse burial contexts is fundamental for developing effective, sustainable restorative conservation practices that preserve both the physical and intangible heritage embodied in bronze artifacts.

Aesthetic integration of chemical technology in restorative

Conservation of bronzes

The core goal of bronze restoration is not only to restore the stability of its physical structure but also to maximize the retention of the historical information and artistic value of cultural relics in the restoration process⁵¹. In this process, technical means are not only tools for physical restoration but also key methods for visual presentation, texture continuation, and retention of historical traces of bronzes. With the continuous progress of science and technology, modern restorative conservation technology has been able to effectively slow down the corrosion process of bronzes by means of composition analysis, corrosion inhibitor treatment, surface sealing and cleaning, etc., and maximize the preservation of its historical original appearance⁵². The application of these technologies not only prolongs the physical life of bronzes but, more importantly, protects and passes on their unique artistic value and cultural connotations. Currently, bronze artifacts undergo a restorative conservation process, as depicted in Fig. 4.

Fig. 4: Shows the entire process of cultural relic restoration. The bronze artifact restoration case diagram in the flow chart is sourced from the restoration case of a Ming Dynasty bronze figurine collected by the Jingmen Municipal Museum of China⁹⁸.

Artifact restoration flowchart.

The application of chemical technology in bronzes mainly focuses on sample testing and analysis, cleaning and descaling, and anti-corrosion treatment⁵³. With the help of these techniques, we can effectively remove harmful rust products, repair damaged parts and form a protective layer on the surface of bronzes to prevent further corrosion. These measures can not only extend the physical life of the bronze but also visually restore its original luster and texture and better show its artistic charm.

Artistic reproduction supported by scientific data. Modern analytical technology not only provides precise data support for the cause of corrosion and material composition of bronzes but also assumes the invisible role of visual authenticity restoration in the process of artistic restoration. The concept of “authenticity” in cultural heritage conservation is complex and multidimensional⁵⁴. As articulated in the 1994 Nara Conference on Authenticity, the understanding of authenticity has expanded beyond a solely material dimension to include historical, cultural, and social values⁵⁵. In this paper, “visual authenticity restoration” refers to restoring the original appearance of the bronze as much as possible based on its physical characteristics, emphasizing the restoration of appearance and the repair of details⁵¹. “Authenticity restoration in art restoration”, on the other hand, is more complex. It is not limited to the restoration of appearance but also involves preserving the traces left by the bronze over time⁵⁶, such as harmless corrosion layers and others. The advancement of science and technology allows us to understand these visual traces in a more precise way, thus preserving their artistic value in restoration. In the restorative conservation of bronzes, modern instrumental analytical techniques provide multi-level, non-destructive means of compositional detection and structural analysis, which provide a basis for the development of scientific restoration programs, as shown in Table 2.

Table 2 Modern analytical techniques in restorative conservation of bronzes

The testing and analysis of bronzes is not only a preliminary step of the restoration project but also a prerequisite guarantee for aesthetic restoration⁵⁷. Among contemporary materials analysis techniques, X-ray fluorescence (XRF) has emerged as a core method for determining the compositional characteristics of bronze. This non-destructive technique is widely employed to analyze alloy ratios, identify casting technologies, and distinguish regional variations in alloy composition across different historical periods^58,59. SEM-EDS is capable of making microstructural observations of the corrosion layers of bronzes. For example, researchers used this technique to analyze 18 bronze vessels from the Rasht Museum’s treasure collection⁵⁹ to obtain more detailed information about their manufacturing process, chemical composition, and microstructure. X-ray diffraction (XRD) is used to identify crystalline corrosion products on the surface of bronze⁶⁰. P.Nel et al.⁶⁰ employed XRD technology to analyze the corrosion layers on different bronze surfaces, successfully identifying crystalline corrosion products such as copper patina (CuO). Their research demonstrates that by identifying the types of crystalline corrosion products, a deeper understanding of the corrosion mechanisms of bronze can be achieved, providing scientific basis for subsequent protection strategies. Furthermore, Raman spectroscopy can identify organic residues in protective coatings on cultural relics, assessing the stability and durability of these coatings to ensure the long-term effectiveness of conservation materials⁶¹. Laser Induced Breakdown Spectroscopy (LIBS) can be used to accurately analyze the elemental composition of metal artifacts and distinguish between the elemental distribution on the surface and inside⁶². Orlic et al.⁶² applied LIBS technology to analyze ancient bronze coins, successfully identifying the content of elements such as copper and silver, and used multivariate analysis methods to perform quantitative analysis. The study shows that LIBS technology not only provides rapid qualitative elemental analysis but also enables high-precision quantitative measurements, making it particularly suitable for non-destructive testing of cultural heritage.

Meanwhile, 3D digital technology has shown unique advantages in scientifically recording the overall shape of bronze, quantifying surface damage, virtually reconstructing missing or deformed parts, and providing visual analysis^63,64. The implementation of this technology combines various advanced scanning and imaging techniques with data analysis methods, including the use of 3D laser scanning, super-depth microscopy, and Vector Displacement Map (VDM) technology^65,66. 3D laser scanning is the core digitization method^65,66, capturing the three-dimensional geometry and surface details of bronze in a non-contact manner. The point cloud data is collected using a 3D laser scanner, clearly showing the geometric and radiometric properties of the object’s surface. The collected data is then processed to eliminate noise and outliers, followed by a registration strategy that progresses from coarse to fine. Key points are detected and extracted from the point cloud. Using these key points, descriptors are estimated, and correspondences between points are established. Finally, pairwise and global registration are applied to the obtained point cloud to ensure high precision in the 3D reconstruction process⁶⁶. Super-depth microscopy plays an important role in detailed observation, providing high-resolution imaging of fine surface damages, corrosion products, and carving marks on the bronze through the synthesis of multiple focal plane images⁶⁷. This ensures that these tiny details are accurately recorded and quantified. The application of Vector Displacement Map (VDM) technology preserves the detailed information captured in the scans and transforms it into reusable “templates”, assisting in the virtual reconstruction of missing components⁶⁵. Through this technology, researchers can piece together fragments and speculate on missing parts, thereby reconstructing a complete 3D model of the bronze.

These 3D data not only provide a scientific basis for the restoration of bronze but can also be digitally displayed using technologies such as Virtual Reality (VR) and Augmented Reality (AR), further enhancing the interactivity and immersive experience of cultural heritage preservation and exhibition^65,68. In addition, by combining Computer-Aided Manufacturing (CAM) technology, these digital models can also be used to create physical replicas, offering multiple possibilities for the preservation and dissemination of cultural relics⁶⁹. Forte (2014)⁶³, in his study of sites such as Çatalhöyük using 3D laser scanning and computer vision modeling, pointed out that 3D digitization can record archaeological stratigraphy in real time, support precise analysis of subtle sedimentary variations and surface features, and facilitate multi-phase reconstructions of artifact structures and spatial relationships through virtual platforms. This “born-digital” data workflow significantly enhances the transparency and reversibility of cultural heritage conservation and interpretation, providing a rich informational foundation for the development of subsequent restoration strategies. Similarly, Levy et al. (2025)⁷⁰ conducted high-resolution 3D digital modeling of Iron Age bronze excavated from the Dor port site in Israel. Through detailed analysis of surface deposits, corrosion patterns, and object structures, they revealed the weathering characteristics of artifacts resulting from prolonged underwater burial. These 3D datasets not only provide critical evidence for assessing the preservation state of artifacts but also serve as precise references for future exhibition design and conservation planning.

Empirical evidence suggests that these scientific tools provide a data-driven foundation for “artistic restoration”, enabling conservators to see beneath layers of corrosion and reconstruct the original luster, tonality, and surface texture evolution of bronze. The synergy between scientific methods and artistic judgment offers a robust basis for color calibration, patina preservation, and decorative reconstruction, thereby ensuring both technical accuracy and aesthetic integrity in the restoration process.

Artistic judgment in chemical interventions. In the process of bronze restoration, cleaning and descaling is not only a technical means to ensure the structural stability of cultural relics but also a key link in determining their aesthetic presentation. Surface deposits, corrosion products, and natural coatings comprise the unique time surface and historical texture of bronze. How to eliminate the damaging factors through scientific methods and at the same time retain these traces of visual and cultural significance is the double challenge faced by the cleaning and descaling stage⁷¹. Cleaning typically targets non-corrosive surface attachments like dirt, dust, and deposits, while descaling focuses on destructive corrosion products like cuprous chloride⁷². Although the two technically belong to different paths, in fact, in the process of operation are often intertwined in the removal and retention to make a balanced choice between. Currently, researchers are using the physical cleaning method and chemical descaling method for bronze surface treatment, as shown in Table 3.

Table 3 Cleaning and descaling in restorative conservation of bronzes

Physical cleaning methods include traditional manual cleaning, laser cleaning, ultrasonic cleaning and agar gel cleaning⁷³. Traditional manual cleaning uses tools such as scalpels, bamboo swabs, and brushes with alcohol or deionized water to remove floating soil, sand, and corrosive attachments from archaeological copper alloy soil on the surface of the artifacts; however, the tools used in this cleaning method may cause secondary damage to the artifacts⁷². Laser cleaning, with the advantages of being non-abrasive and non-contact, is a non-destructive and precise and controllable decontamination technique that has been applied to the restoration of high-value bronze artifacts and is especially suitable for large bronze artifacts. However, it may affect the appearance of harmless rust^72,74. Ultrasonic cleaning, on the other hand, is more suitable for small bronzes, where high-frequency vibrations are applied to the liquid medium to loosen and dislodge surface attachments. Studies have shown that this method is highly effective in removing stubborn deposits without damaging inscriptions or fine carvings⁷³. Deionized water, because it contains no minerals or ions, can effectively clean the surface of bronze artifacts without causing corrosion or deposition, thus preserving the details and surface condition of the bronze⁷⁵. The agar gel cleaning method is suitable for fine, controlled localized cleaning and performs particularly well in removing contaminants, light corrosion products, salts and old restoration residues. In bronze restoration, agar gel not only provides a gentle cleaning effect but is also effective in avoiding damage to artifacts caused by chemical cleaners^75,76.

The purpose of chemical descaling is to remove the corrosion layer from the surface of the bronze and prevent further deterioration. Since chemical methods are more targeted in removing corrosion products, chemical cleaning methods are widely used in the descaling process. Complexing agent cleaning is a milder method of removing patina in which EDTA (ethylene diamine tetraacetic acid) selectively complexes the patina without damaging the metal matrix and is therefore widely used in museum restoration projects^75,77. Weak acid solutions, such as citric acid and acetic acid, are used to dissolve copper oxides and copper carbonates. In particular, citric acid⁷⁸ is effective in removing copper corrosion products. However, the pH value must be strictly controlled during use to prevent irreversible damage to the surface of the bronze. In recent years, with the development of restoration technologies, methods such as PVA-EDTA composite hydrogel and PVA-TEPA composite film have been proposed and applied in the field of bronze restoration. These methods utilize the combination of PVA and chelating agents to efficiently remove rust layers while protecting the surface of the bronze. The PVA-EDTA⁷⁹ composite hydrogel method forms a thin film over the surface and uses chelation to remove rust, while the PVA-TEPA⁵⁶ composite film method uses a similar approach to chelate copper ions with TEPA, making it particularly suitable for complex or fragile bronze surfaces. These methods effectively reduce the damage caused by traditional acid cleaning and show promising application prospects. Additionally, there are various independent chemical rust removal methods, such as the silver oxidation method, zinc powder displacement method, and semi-sodium carbonate method⁸⁰. In the future, with the continuous development of new materials and technologies, more innovative rust removal techniques are expected to be proposed, thereby improving the efficiency and quality of bronze restoration and further promoting the protective restoration of bronze⁸¹.

With the concept of heritage conservation changing from pure functional stability to visual information and historical semantic integrity, the boundary between cleaning and descaling is gradually blurred, and the restoration practice emphasizes technical synergy and visual preservation. In the restoration practice, the comprehensive operation of technical synergy and visual preservation is emphasized. Restorers need to judge the aesthetic significance of the rust layer under the premise of maintaining scientific validity, including which patches of corrosion and which layers of cladding should be retained and which are sources of structural damage that should be completely removed^13,80,82. For example, in the case of the restoration of a Warring States Period Panchi Pattern Horse Head Bronze Basin Excavated from Zhao Wang M1 Tomb Group in Zhangzhuangqiao, China, the restorers used a combination of ultrasonic cleaning, dechlorination with 5% sodium sesquicarbonate solution, and rinsing with distilled water to effectively control the spread of bronze disease while preserving the weathered features of the decoration and ornamental layers⁸². This process not only shows the precise operation of the technical level but also reflects the respect and reproduction of the original appearance of the cultural relics and the sense of historical time.

Balance of chemical stability and visual continuity. The core of bronze restoration is not only to repair the physical structure of artifacts but also to ensure that cultural relics are preserved for a long time in the process of maximizing the protection and continuation of their historical appearance and artistic value. Anti-corrosion and sealing treatment, as an important part of the restoration process, undertakes the dual tasks of stabilizing the material basis of bronze, inhibiting the corrosion process, and protecting the aesthetic characteristics of the surface of the artifacts. Their ultimate goal is not only to repair the physical state of the artifacts but also to provide lasting support for their historical context and artistic senses through chemical and material protection mechanisms. By choosing the right corrosion inhibitors and sealing materials, restorers are able to prevent further corrosion while preserving the natural weathering and historical traces of the bronzes³⁵. These protective techniques not only prevent physical damage such as oxidation and pitting but also require fine consideration of aesthetic features such as surface texture, color tone, and glossiness to ensure that the appearance and texture of the artifacts are restored and protected to the greatest extent possible after restoration^35,80. Therefore, anti-corrosion and sealing are not only the physical protection of the artifacts but also the historical beauty and artistic level of the bronze’s continuous protection^35,80,83.

One of the core objectives of bronze restoration is to prevent its further corrosion, especially to inhibit the attack of chloride ions on the artifacts. Corrosion inhibition and sealing treatments are mainly designed to cope with the problem of continuous corrosion of the bronze body and slow down the corrosion process through effective measures⁸⁴. Recently, researchers have developed various corrosion inhibitors and sealing materials to reduce the occurrence of oxidation and pitting while maximizing the preservation of the original texture and historical information of the artifacts⁸⁵.

Corrosion inhibitors mainly work by creating a stable protective layer on bronze that acts as a barrier or forms chemical bonds to prevent metal damage from the environment^56,. More importantly, the protective layer formed by the corrosion inhibitor on the metal surface is not only a physical barrier but also determines the restoration effect of the surface color, reflectivity and texture after restoration. Common bronze corrosion inhibitors can be divided into the following categories: conventional chemical corrosion inhibitors, compounded corrosion inhibitors, and green corrosion inhibitors (Table 4). Conventional chemical corrosion inhibitors usually reduce the oxidation rate of the metal by forming complexing or adsorption films with the copper surface⁶. Among them, BTA is the most widely used corrosion inhibitor⁸⁶; it can combine with the copper surface to form a stable Cu-BTA complexing, thus effectively preventing the erosion of chloride ions. BTA has been widely used in the corrosion inhibition and restoration of excavated artifacts^87,88,89, such as the corrosion inhibition and restoration of excavated artifacts from the Haihun Marquis Tomb of the Western Han Dynasty, excavated artifacts from Yili, and excavated artifacts from the Han Tomb Group of Hepu in Guangxi, etc. However, BTA is classified as a medium toxic organic compound, possesses certain carcinogenic properties, and its long-term use can be very harmful to the health of heritage conservation workers¹⁰. Additionally, BTA exhibits a better corrosion inhibition effect in alkaline media compared to its relatively poor performance in acidic media³⁵. Due to the limited effect of a single corrosion inhibitor, researchers have gradually developed compounded corrosion inhibitors, i.e., to improve the corrosion inhibition performance through the synergistic effect of two or more corrosion inhibitors^35,90. For example, the composite corrosion inhibition system of BTA and sodium formate (SFA) can form a denser protective layer on the surface of bronzes and improve the stability of corrosion protection⁷². Silver oxide (Ag₂O) combined with BTA-treated bronzes showed higher durability, and its long-term inhibitory effect on bronzing disease was confirmed in several experiments⁹¹. Recently, the concept of green chemistry has been promoted in bronze restoration, and researchers have developed non-toxic and environmentally friendly bio-based corrosion inhibitors, such as plant extracts like chitosan, tannic acid and tea polyphenols^6,92,93. Chitosan is a natural polymer derived from crustaceans with beneficial antioxidant properties. Plant extracts such as tannic acid and tea polyphenols have also been shown to reduce copper pitting and have become the focus of research on bio-based corrosion inhibitors. These natural substances not only exhibit eco-friendly properties but also effectively reduce the environmental impact traditionally associated with synthetic chemicals.

Table 4 Anti-corrosion treatments in restorative conservation of bronzes

In the process of bronze restoration, the choice of sealing material is crucial. Ideal sealing materials not only need to have durability, transparency, and waterproofness, but they should also avoid, as much as possible, the impact on the appearance of the objects⁹⁴. Currently, sealing materials are primarily divided into two categories: traditional sealing materials and modern polymer sealing materials. Traditional sealing materials often adopt paraffin sealing⁹⁵. The paraffin sealing method is inexpensive, simple to operate, and has better reversibility. However, paraffin wax has poor aging resistance, oxidizes and yellows easily after a long period of time, and may reduce the permeability of the bronze surface. Modern polymer sealing materials mainly use organic-inorganic hybrid sealing materials (such as Ormocer) and nano-coatings (such as Paraloid B72 acrylic resin)^71,96,97. Ormocer is a transparent, highly stable organic-inorganic hybrid material that is able to maintain the original texture of cultural relics for a long period of time and provide effective waterproof and anti-pollution protection. The nano-coating has excellent transparency, which will not affect the original color of the artifacts, and at the same time, it can enhance the corrosion resistance of the bronze surface. Paraloid B72 acrylic resin is an organic polymer sealing material that possesses the characteristics of high stability, reversibility, and excellent transparency, and therefore has been widely used in archaeological and museum restoration work.

The practice of integrating bronze restoration techniques and aesthetics

Bronze restoration not only focuses on the physical structure of the artifacts but also emphasizes the reproduction of historical and artistic values. In the process of restoration, the application of chemical technology in detection, cleaning, corrosion inhibition and sealing not only ensures the long-term stability of cultural relics but also provides a guarantee for the continuation of their aesthetic effect and sense of history. With the development of new chemical restoration technology, the restoration of bronzes has realized a breakthrough in technology and received profound attention at the aesthetic level. In this paper, there are two cases, the restoration of bronze figurines from the Ming Dynasty assemblage in Jingmen City Museum, China, and the conservation and restoration of bronze arrowheads in Cairo Military Museum, Egypt, to discuss how modern chemical technology can be combined with the aesthetic demand in the restoration process to ensure that the cultural relics retain their historical aesthetics, color and artistic value on the basis of their structural stability.

Protection and restoration of first-class cultural relics in the collection of Ming Dynasty assemblage bronze figurines in Jingmen City Museum, China⁹⁸. In this case, the restoration team strictly followed the principles of reprocessability, recognizability, and minimal intervention in response to the multiple issues like fractures, hard knots, mineralization, perforation, and corrosion on the surface of the artifacts after excavation. Under the premises of reprocessability, identifiability, and the minimum intervention principle, the restoration team combines traditional techniques with modern technology. Through the steps of chemical descaling, corrosion inhibition and sealing (Fig. 5), the team not only ensured the stability of the structure of the artifacts but also preserved their historical coating and decorative details as much as possible so that the restored bronze figurines aesthetically presented a more natural and authentic sense of history.

Fig. 5: Shows the process of restoring the first-class cultural relic, the Ming Dynasty combined figurines, collected by Jingmen Museum.

Work flowchart for the restorative conservation of the Ming Dynasty assemblage bronze figurines in the collection of the Jingmen City Museum, China⁹⁸.

Disease analysis and technology assessment.By using modern analytical techniques such as SEM and EDS, the restoration team conducted a systematic analysis of the corrosion products on the surface of the bronze figurine and identified damage caused by harmful corrosion substances like rust and fibrous iron minerals. To ensure that the restored figurine is both stably preserved and retains its artistic value, the team removed harmful rust while preserving beneficial corrosion layers such as malachite. This selective removal and retention strategy ensured that the original visual historical feel of the bronze was maintained, allowing the restored figurine to retain a natural and authentic historical appearance in both color and texture.

Chemical descaling and corrosion inhibition treatment process. To remove the harmful surface rust and soil contamination, the restoration team used a topical treatment with a 3-5% solution of oxalic acid (C₂H₂O₄). The complexation reaction between oxalic acid and iron oxides ensured effective removal of the harmful rust while avoiding excessive corrosion of the natural texture of the copper surface. Subsequently, BTA was used as a corrosion inhibitor to penetrate the copper surface and form a uniform protective film. This protective layer inhibits erosion from the external environment and effectively preserves the sense of history and depth of color of the objects.

Chemical-assisted applications in welding and mating technology. The Chinese Ming Dynasty bronze figurines were excavated with varying degrees of defects, and the restoration process required replacing these missing parts. To ensure the consistency of the mending material with the original material’s texture, ornamentation and color tone, the team adopted a combination of copper skin cutting and atomic ash mending. Prior to soldering, the area to be soldered was chemically pre-treated, using a quantitative chemical reagent to remove localized layers of stubborn rust and activate the new copper surface to ensure a strong metallic bond was formed at the soldered area. At the same time, the ratio and tone of the atomic ash were precisely regulated during the replating process and continuously adjusted through sample comparison so that the replated traces blended in with the original artifacts and preserved the historical information to the greatest extent possible.

Digital monitoring and evaluation of restoration effects. In order to comprehensively record and assess the restoration effect, a handheld 3D scanner was used before and after the restoration to establish a digital model of the artifacts and to visualize the overall shape and detail changes of the artifacts before and after the restoration through comparative analysis. In addition, X-ray flaw scanning was used to conduct non-destructive testing of the welding and mending parts to confirm the continuity and solidity of the restored structure. These digital means not only provide an objective evaluation basis for this restoration but also lay a solid foundation for future long-term monitoring and dynamic maintenance.

Nanocomposite coating protection of bronze arrowheads at the Cairo Military Museum, Egypt⁹⁹. During the conservation and restoration of bronze arrowheads at the Cairo Military Museum, the research team used nanocomposite coating technology to enhance the corrosion resistance and extend the preservation life of the bronzes. Due to the serious corrosion phenomenon on the surface of these bronze arrowheads in the collection, for example green rust, a black-brown oxidized layer, and local mineralization, the researchers used various modern analytical techniques to investigate the corrosion mechanism in depth and finally chose zinc oxide nanoparticles (ZnO) with Paraloid B-48 or Paraloid B-66 composite coating as the restoration solution.

Disease characterization and corrosion mechanism analysis. About 32 bronze arrowheads in the collection of the Military Museum in Cairo showed intensive pore-like corrosion, localized mineralization, and green rust layering on their surfaces due to long-term exposure to high humidity and chloride-rich environments, as shown in Fig. 6. By using advanced analytical tools such as SEM and XRD, the team found that the corrosion was mainly caused by chloride salt and sulfide contamination. In removing the corrosion layers, the team adopted a selective removal strategy to remove the green rust and black-brown oxidized layer while preserving the historical traces and texture of the bronze surface, which is essential to ensure the original artistry and visual hierarchy of the arrowheads Fig. 7.

Fig. 6: shows the intensive pore-like corrosion, localized mineralization, and green rust layering on about 32 bronze arrowheads in the Cairo Military Museum’s collection, along with the results of corrosion analysis.

a Shows the images of collective arrowheads before the treatment showing the different deterioration aspects;(b)Shows SEM&EDS ex., for a sample from the arrowhead, the photo shows the deterioration of the alloy, and the SEM&EDS scan shows the elemental composition of the arrowheads;(c)Shows SEM&EDS ex., for a second sample from the arrowheads, the photo shows the appearance of the rough surface closely and the calcified rust layers and SEM&EDS Scan shows the elemental composition of the arrowheads;(d)Shows XRD scan for the corrosion products of the first group of arrowheads⁹⁹.

Fig. 7: Electrochemical performance test of nanocoating.

(a) Open circuit potential curves represent the effect of adding ZnO nanoparticles on the corrosion behavior of bronze in 3.5% NaCl solution containing A 2% Paraloid B-48 and B Paraloid B-66; (b) Polarization curves represent the effect of adding ZnO nanoparticles on the corrosion behavior of bronze in 3.5% NaCl solution containing. A 2% Paraloid B-48 and B Paraloid B-66⁹⁹.

Design and application of nanocomposite coating. For chloride salt-induced bronze corrosion, the research team innovatively developed a ZnO nanoparticle/Paraloid composite coating and designed a two-step chemical intervention method. The first step involved cleaning the surface. The surface was first ultrasonically cleaned for 15 min using a mixed ethanol-deionized water solution (1:1) to remove soluble salts and loose corrosion products from the surface. For localized recalcitrant hardeners, a 5% citric acid gel sealing treatment was applied for 20 min to selectively remove chloride salt contaminants through chelation. Second, corrosion inhibition coating. 10 wt% ZnO nanoparticles (particle size about 50 nm) were dispersed in Paraloid B-48 or B-66 resin (dissolved in acetone at 5% concentration), and the homogeneous dispersion was ensured by magnetic stirring and ultrasonic treatment. The coating was applied to the surface of the arrowheads by the dip-coating method in two coats with an interval of 24 h between each coating to form a dense composite film layer with a thickness of about 50 μm. This coating not only enhances the corrosion resistance of the bronze arrowheads but also effectively maintains the color and luster of the artifacts, ensuring that the artistic texture and original appearance of the bronze arrowheads can be continued after restoration.

Electrochemical performance test. The electrochemical performance test indicates that the nanocomposite coating technology has a broad application prospect in the field of bronze protection. The introduction of ZnO nanoparticles not only enhances the corrosion resistance of the bronzes but also maintains the original appearance and color of the artifacts, as shown in Fig. 8. This coating technology not only ensures the structural stability of the bronzes after restoration but also maximizes the retention of their historical aesthetics and cultural values, providing a more efficient and sustainable solution for bronze conservation.

Fig. 8: The restored bronze arrowheads from the military Museum in Cairo, Egypt.

a–d Show the arrowheads after treatment⁹⁹.

In the practice of bronze restoration, chemical technology not only enhances the stability and corrosion resistance of cultural relics but also provides a new path for the continuation of historical aesthetics. The restoration of Ming Dynasty assemblage bronze figurines in Jingmen City Museum, China, achieved a balance between physical integrity and visual coordination through selective descaling and precise patching; the nano-coating technology of bronze arrowheads in Cairo Military Museum, Egypt, preserved the temporal texture of the bronzes while protecting their materials. The above two cases indicate that restoration is not just fixing the bronze’s material level but also reproducing its cultural symbols and artistic value. With the development of science and technology, how to make chemical technology in the process of restoration serves both scientific conservation and respects the historical aesthetics of bronzes, which has become a new guideline for cultural relics restoration. It is in this context that the concept of symbiosis between art and chemistry has gradually become the core topic of bronze conservation, promoting the development of restoration methods in the direction of interdisciplinary integration.

Results

Symbiosis of art and chemistry

The restoration and conservation of bronzes is essentially an in-depth dialogue between the spirit of art and chemical technology – the former guards the aesthetic soul of civilization, while the latter perpetuates the eternal life of matter. The restorative protection of chemical technology ensures the long-term preservation of the bronzes, while artistic aesthetics maintains the visual and cultural value of their historical precipitation. In the future, with the continuous development of AI, bionic materials, digital technology and green chemistry, bronze restoration will further realize the integration of science and art so that thousand-year-old historical relics can continue to inherit their unique aesthetic value and cultural significance in modern society.

Aesthetic principles and Standardized Processes in bronze restoration. In the field of cultural relics restoration, authenticity has always been one of the core principles^54,55,100. The main goal of chemical restoration is to stabilize the structure of bronzes and prevent corrosion from expanding, but if over-intervention occurs, it may destroy their original historical beauty; on the contrary, artistic restoration places more emphasis on the visual harmony of beauty and cultural inheritance, but if it only pursues the appearance of restoration and ignores the scientific basis of the material, it may lead to a lack of long-term stability. Therefore, the symbiosis of art and chemistry requires restorers to find a balance between physical protection and aesthetic restoration. Restoration is not only a technical act but also a humble imitation of natural processes⁵⁵. The patina layer of bronze is not a mere corrosion product but a material carrier of historical aesthetics. It is necessary to establish a dual framework of rust layer taxonomy and ecological and ethical restoration. This intervention logic, while removing the corrosive rust affecting the bronzes, respects the historical patina formed by the natural oxidation of the bronzes (e.g., the deep luster of the black lacquered ancient, the mottled texture of the jujube skin red) so that the patina becomes a silent note of the time aesthetics.

However, because restoration practices often lie in the ambiguous space between technical rationality and aesthetic judgment, different conservators may apply varying standards in assessing the “extent of intervention”, “rust layer preservation” and “visual consistency”¹⁰¹. This often results in similar types of bronze displaying stylistically divergent restoration outcomes across different countries and institutions. While this phenomenon reflects the diversity inherent in artistic restoration, it also exposes the lack of unified restoration standards, leading to insufficient scientific reproducibility and risks to long-term sustainable conservation¹⁰¹. Therefore, while respecting case-specific differences and aesthetic freedom, there remains a need to promote the standardization of the bronze restoration process by establishing a framework guided by the principles of “traceability, communicability, and reproducibility”. In recent years, several exploratory approaches have been proposed in the academic field. For instance, Gasparetto and Baratin¹⁰² have introduced the concept of “Conservation 4.0” from the perspective of digital documentation. They emphasize the need to follow a standardized data workflow of “collection-management-reproduction” during the restoration process, which aims to make the restoration process transparent, shareable, and capable of generating reproducible digital workflows. Meanwhile, Li et al.¹⁰³ have further demonstrated through archaeological field studies that the lack of quantifiable and standardized evaluation criteria introduces significant uncertainty in the extraction and preservation of bronze. They propose a comprehensive health assessment framework that integrates both subjective and objective indicators, promoting a more scientific and standardized pre-restoration evaluation process.

Standardization does not imply the dissolution of individualized treatment; rather, it provides a methodological framework for the “creativity of restoration”, enabling aesthetic judgments to be grounded in evidence and chemical interventions to be guided by rational principles. Only by establishing a methodological bridge between institutional structure and ethical aesthetics can the restoration of bronze truly transition from an empirical craft to a knowledge-based discipline.

Cross-border synergistic innovation in chemistry, aesthetics and materials science. The essence of bronze restoration lies in building a bridge between material science and cultural perception. Multidisciplinary restoration is the core trend in modern bronze conservation^104,105,106, requiring the integration of technologies from fields such as materials science, data science, and artificial intelligence, alongside traditional chemical and artistic restoration techniques. This shift ensures that chemistry, aesthetics, and materials science are no longer isolated disciplines but are progressively coupled methodologically to achieve an optimal balance in post-restoration artifacts in terms of stability, aesthetic consistency, and environmental adaptability¹⁰⁷. Modern restoration philosophy is fostering a cross-disciplinary collaborative mechanism, transitioning bronze restoration from a singular technical operation to the construction of multidimensional pathways that are perceptible, assessable, and shareable.

In recent years, advancements in materials science, particularly the application of nanostructured fluids and polymer composites, have provided more sustainable and adaptable solutions for both restoration and conservation. Research has shown that these materials not only closely replicate the optical properties, color, and texture of the original surface but also demonstrate superior performance in terms of mechanical strength, environmental stability, and reversibility, significantly enhancing the precision and long-term stability of restorations¹⁰⁸. Furthermore, the integration of multiple disciplines has propelled the technological evolution of precise restoration techniques, particularly in addressing the complex and varied corrosion patterns on bronze surfaces. Recent developments in Raman spectroscopy-based composition identification systems and artificial intelligence-driven image classification algorithms have enabled restoration teams to distinguish between “destructive corrosion” (such as cuprous chloride) and “stable oxide layers” (such as malachite)¹⁰⁹. This, in turn, has facilitated the development of an “intelligent rust removal” strategy, where only regions potentially threatening the structural integrity are intervened upon, while preserving historical patina and aesthetic texture. This selective intervention mechanism achieves an organic balance between scientific protection and authentic restoration.

Standardized terminology is particularly crucial in interdisciplinary collaboration. Different disciplines may define, describe, and approach the same problem in divergent ways. Unified terminology and standards can effectively address this issue, thereby promoting efficient communication and data sharing among cross-disciplinary teams. Currently, inconsistencies in terminology usage, data descriptions, and restoration process documentation across different fields have severely hindered the efficiency of information sharing and academic dialogue¹¹⁰. To address this, researchers are exploring the integration of ontology construction and semantic interoperability methods into restoration practices. For instance, Hu Hanlin¹¹⁰, in his study of bronze digital collections, proposed the construction of a bronze knowledge graph based on Neo4j to establish semantic links between “vessel type–inscriptions–diseases”, thus facilitating data sharing and deep retrieval. Moraitou et al.¹¹¹ designed an ontology-based intervention decision-support framework that integrates multi-disciplinary knowledge through formalized modeling, providing traceable logical support for the selection of restoration strategies. Meanwhile, Carriero et al.¹¹² introduced a pattern-driven ontology design method in the European Cultural Heritage project ArCo, aligning it with CIDOC-CRM to enable semantic interoperability across institutions and languages. Wang Qian¹¹³ pointed out that terms related to bronze restoration in China still suffer from issues such as “lack of standardization, inconsistent English translations, and missing cultural concepts”, which limit the establishment of standardized processes. She suggests building on national standards such as the Guidelines for the Protection and Restoration of Metal Artifacts in Museum Collections and integrating local practices and traditional craftsmanship to ensure effective connections between terminology systems and procedural data.

In the future, with the integrated application of knowledge graphs, semantic networks, and intelligent ontology recognition technologies, interdisciplinary collaboration will evolve from “cooperative operation” to “cooperative cognition”. This evolution will drive the transition of bronze restoration from an empirical craft to a knowledge-driven intelligent collaboration system, establishing a systematic support framework that encompasses terminology standards, process documentation, and knowledge interoperability.

AI-driven precision and predictable restoration. In AI-driven accurate and predictable restoration, artificial intelligence has moved from the assisted analysis stage to the intelligent decision-making stage. Based on deep learning algorithms, AI can automatically identify and infer missing inscriptions or ornaments and combine with 3D modeling technology to provide accurate restoration reference solutions¹¹⁴. Convolutional Neural Networks (CNNs) are the most widely used cultural relic recognition models. CNNs extract features from local areas of the image through convolution, pooling and other operations and can effectively capture the visual features of cultural relics’ ornamentation and modeling¹¹⁴. Furthermore, Huang et al.¹¹⁵ proposed a digital heritage management approach that combines knowledge graphs with deep learning algorithms. By extracting entities and relationships, they developed a structured and interactive knowledge graph. This framework facilitates the processing of dispersed data and provides intelligent support for restoration decision-making, thereby enhancing data integration and information extraction capabilities in cultural heritage management. The combination of deep learning and knowledge graphs makes information sharing and interdisciplinary collaboration in artifact restoration more efficient, promoting the intelligentization and traceability of restoration work.

Virtual restoration and digital reconstruction technology further strengthen this process by constructing a digital twin through high-precision 3D scanning and multimodal data fusion. Wang Lele¹¹⁶ proposes an axisymmetric virtual restoration method based on 3D modeling for the restoration of damaged stone statues in the collection of Huanghua City Museum, China. This method uses 3D laser scanning technology to reconstruct the 3D model of cultural relics and carry out virtual restoration of the damaged cultural relics, avoiding the secondary damage to cultural relics in the process of restoration to the maximum extent. The Aïoli platform proposed by Abergel et al.¹¹⁷ leverages 3D annotations based on real-world data and cloud computing to enhance the collaboration and traceability of artifact restoration. It provides interdisciplinary teams with a solution for synchronized documentation, restoration simulation, and data sharing. AR/VR technology expands the interactive dimension of restoration and provides a clearer and more intuitive visual space for the restorers through the cooperation of wearable AR equipment, providing a clearer and more intuitive space for the formulation of cultural relics restoration plans, fragment extraction and separation of different materials attached to the relics. It provides more accurate data support for the formulation of restoration plans, the extraction of fragments, and the separation of different material attachments¹¹⁸.

The collaborative application of these technologies has transformed bronze artifact restoration from being primarily “experience – driven” to “data – intelligence – driven”. The seamless integration of AI, digital twins, AR/VR, and other technologies has not only improved the scientific rigor and precision of restoration efforts but has also made cultural heritage preservation more efficient and accurate. As technology continues to evolve, these intelligent technologies will play an increasingly pivotal role in the restoration of cultural relics, offering robust support for the preservation and recreation of cultural heritage.

Intelligent monitoring and long-term storage. The restored bronzes do not mean the end of the restoration work; the long-term monitoring and dynamic maintenance after the completion of the restoration determine the future preservation status of the bronze¹¹⁹. Bronze, as a valuable cultural heritage, requires long-term preservation, which not only protects its physical structure but also involves the ongoing transmission of its cultural connotations and historical significance. Heritage studies¹⁵ suggest that heritage is not merely static objects; they are dynamic cultural symbols that have a close interaction and connection with society, history, and the environment. The process of site formation¹⁵ emphasizes how the storage environment, climate changes, and human activities across different historical periods collectively shape and influence the preservation state of heritage. Therefore, the long-term preservation of bronze depends not only on restoration but also on the continuous maintenance and dynamic management provided by intelligent monitoring technologies.

In this field, the introduction of Smart Monitoring technology has shifted heritage conservation from passive restoration to active intervention⁴⁵. Through these technologies, sensors can be embedded in display cases used for showcasing or protecting bronze to monitor environmental parameters such as temperature, humidity, and light intensity in real time, helping restoration experts promptly identify potential risk factors. The application of intelligent monitoring technologies provides a novel approach to artifact protection. In the past, restoration work was typically based on the experience of experts, a process that was relatively subjective and difficult to quantify. However, modern intelligent monitoring systems, through Internet of Things (IoT) technology, establish real-time data collection networks and integrate edge computing with cloud-based data analysis platforms, offering precise, quantitative support for conservation decision-making¹²⁰.

More importantly, with the continuous advancement of big data and artificial intelligence-based algorithms, every stage of the restoration process can be digitized and traceable, and even potential corrosion or damage issues that bronze may face can be predicted in advance¹²¹. Through image recognition technology powered by artificial intelligence¹²², restoration experts can analyze surface changes in real time, promptly detecting minor cracks, color differences, and other damages, while predicting their development trends. This data-driven preventive conservation approach not only improves the accuracy and efficiency of restoration but also significantly reduces human error and subjective bias¹²⁰. By integrating artificial intelligence with sensor data, restorers can more precisely identify damage trends and take appropriate protective measures. This intelligent and automated monitoring system undoubtedly provides strong support for the long-term preservation of bronze.

Furthermore, blockchain technology, as an innovative tool for digital heritage management, is gradually being applied to the protection and restoration of cultural heritage. Due to its decentralized nature, blockchain can provide a transparent and immutable digital record of bronze’s history, ensuring the integrity and authenticity of the restoration process¹²¹. The integration of blockchain with the Internet of Things (IoT) and artificial intelligence (AI) technologies not only enhances the effectiveness of artifact protection but also promotes global cooperation and data sharing in cultural heritage preservation¹²³. This blockchain-based transparent data management system provides a solid technological foundation for the restoration and preservation of bronze. The combination of intelligent monitoring and digital management methods offers new solutions for the global protection of cultural heritage. In the context of increasing globalization and digitization, utilizing digital technologies, intelligent tools, and cross-border data-sharing platforms can foster international cooperation and exchange in cultural heritage preservation¹²⁴. In the future, as these technologies continue to evolve, the protection of bronze and other artifacts will no longer solely rely on traditional restoration methods but will develop towards a more predictable, quantifiable, and monitorable approach.

The fusion of chemistry and artistry is driving bronze restoration into a new stage of multidisciplinary, intelligent, green and sustainable. From precise material science to AI-assisted intelligent restoration to intelligent monitoring and protection programs after the completion of restoration, modern bronze restoration is constantly breaking through the traditional limitations and moving towards a finer, more scientific and more sustainable direction. In the future, the restoration of cultural relics should not only focus on the protection of the material level but also strengthen the reproduction of cultural values and long-term monitoring so that bronzes can continue to glow with historical luster in the course of time.

Discussion

This paper provides a systematic overview of the latest progress of chemical technology in the restorative conservation of bronzes, analyzes the corrosion mechanism of bronzes, and focuses on the aesthetic integration of modern analytical techniques, cleaning and descaling methods, corrosion inhibitors and sealing materials in restorative conservation of bronzes. Through case studies, chemical interventions play an important role in slowing down the corrosion of bronzes, enhancing their long-term stability, and preserving historical aesthetics. In addition, the paper emphasizes the importance of interdisciplinary collaboration for bronze restoration, particularly, the importance of standardized restoration processes and terminology in the integration of multidisciplinary approaches with artificial intelligence and digital technologies. Combining modern technological means and artistic restoration concepts, bronze restoration is dedicated to physical restoration and lies in restoring the artistic level, visual feeling and historical traces of the objects. The study draws the following main conclusions.

The corrosion of bronzes is affected by various factors such as burial environment, material composition and time. A chlorine-rich environment is easy to induce bronze disease, high humidity will accelerate the diffusion of corrosion products, and the denseness of the oxide layer has an important role in regulating the corrosion rate. Through XRF, SEM-EDS, XRD and other analytical techniques, we can accurately analyze the type of corrosion and the microstructure of the bronzes, providing data support for scientific restoration.

The choice of cleaning and descaling techniques needs to be flexibly adjusted according to the degree of corrosion of the bronzes. Physical cleaning methods (e.g., laser cleaning, ultrasonic cleaning) are suitable for light contamination, while chemical descaling (e.g., complexing agent cleaning, ionic liquid technology) is more effective for chlorinated corrosion. The strategy of phased treatment can improve the accuracy of restoration and reduce secondary damage to the artifact body while helping to preserve the historical aesthetics.

Corrosion inhibitor and sealing technology are the keys to delaying the secondary corrosion of bronze. Traditional corrosion inhibitor BTA is widely used, but there are toxicity and stability problems. Green corrosion inhibitors (e.g., chitosan and tannic acid) are gradually becoming a research hot spot. Nano sealing materials (e.g., ZnO/Paraloid composite coating, Ormocer) show promising prospects in improving weather resistance and reversibility but still need to optimize their long-term stability and visual coordination to achieve comprehensive protection and aesthetic restoration of cultural relics.

On this basis, this paper further proposes the future development direction of bronze restoration under the interdisciplinary perspective: by improving the accuracy of modern detection technology and combining artificial intelligence algorithms, big data analysis and virtual reality technology (VR/AR), it can reveal the corrosion evolution mechanism of bronzes in a more in-depth way. By simulating the restoration process in advance through virtual simulation, it can provide guidance for personalized and precise restoration solutions. By establishing standardized workflows, the bronze restoration process will become more transparent, reproducible, and shareable. Through the standardization of terminology and the normalization of data management, the bronze restoration industry will move towards a more systematic, standardized, and sustainable direction.

At the same time, attention should be paid to the balance between the reversibility of chemical interventions and artistic originality to ensure that the historical envelope and cultural aesthetics are preserved to the greatest extent possible. For example, harmless corrosion layers that do not affect the artifact’s stability embody the unique aesthetic value imparted by time. In the future, low-toxic, environmentally friendly corrosion inhibition technology and intelligent restoration technology will become an important trend in bronze conservation. In addition, digital monitoring and the application of blockchain technology will further promote the transformation of bronze conservation from passive restoration to active, real-time monitoring and maintenance. Through multidisciplinary cooperation and the improvement of the global cultural heritage protection network, the restorative conservation of bronzes will move towards a more efficient, scientific and sustainable new era.