Conservation and restoration of Tang White Marble Panlong Stone Lantern at Beiyue Temple

Abstract

A large number of cultural relics are of great historical value, but many have been forgotten due to the temple’s neglect for a long time, and their condition has greatly worsened due to the surrounding environment. This research aims to fill the void of tailored conservation techniques on white marble artifacts from the Tang dynasty by concentrating on the preservation and restoration of Tang White Marble Panlong Stone Lantern, a first-class cultural relic. It analyzes the problem using the historical approach and develops the cultural-architectural context first, followed by pathological studies using XRD, XRF, and FTIR spectroscopy. The dominant salts that contributed to the deterioration were found to include soluble salt (SO₄²⁻ concentrations up to 1197.88 ppm), material loss, structural deterioration, and de-bonding. During the restoration stages, photogrammetry techniques and advanced documenting threedimensional scanning were utilized to create comprehensive 3D models, space planning and VZB virtual reconstruction principles were applied for thorough placement, and finally, penetrating reinforcing JS-01 which is composed of polyurethane, SiO₂, and TiO₂ was utilized for consolidation. After restoration, the model exhibited improved structural integrity, surface stability, and a more stable structure, void of hazardous salt crusts and deposits. The approach presented in this study addresses the preservation of marble artifacts having complex environmental exposure while respecting the existing damage and the need to provide unobtrusive intervention enhances efforts for integrated preventive conservation of stone heritage.

Introduction and literature review

As integral components of cultural heritage, stone relics embody significant historical and artistic values (Smith, Brown, & Johnson, 2015). However, prolonged exposure to the elements renders them highly vulnerable to various destructive factors, which can severely compromise their intrinsic worth. Consequently, the restoration of stone cultural relics is both urgent and crucial, aimed at preserving and revitalizing their inherent value through meticulous conservation efforts. This paper focuses on the restoration of the Panlong stone lamp at Beiyue Temple, employing innovative techniques and materials to enhance the longevity and esthetic appeal of the artifact. The goal is to extend the relic’s lifespan and improve its visual presentation for visitors (Wang, Li, & Zhao, 2019). The restoration process integrates advanced technological methods to monitor and analyze the stone’s condition and deterioration, identifying the root causes of damage (Bonazza, Sabbioni, & Ghedini, 2009). Traditional restoration methods are combined with cutting-edge technologies; for instance, while traditional stone materials are used for repairs, virtual restoration technology is also applied. Through three-dimensional scanning, the precise adhesive surfaces required for restoration are digitally mapped, allowing for accurate replication and minimizing alterations to the original stone surface, thereby preserving the relic’s authenticity more effectively (Zhang, Liu, & Chen, 2020). Moreover, in the selection of materials, a novel infiltration reinforcement and sealing material, JS-01, was utilized. This material not only maintains the internal cohesion and strength of the reinforced stone but also offers improved air permeability and weather resistance compared to traditional silicone-based reinforcements. Through interdisciplinary collaboration, the development of more environmentally friendly and sustainable conservation materials and techniques is prioritized, ensuring the enduring preservation of stone cultural relics. This comprehensive approach not only safeguards the physical integrity of the stone relics but also enhances their resilience against environmental challenges, ensuring that they continue to be a source of cultural enrichment and historical insight for future generations (Li, Zhang, & Sun, 2021).

Case study: description and current preservation status

Tang White Marble Panlong Stone Lantern is a significant relic from the prosperous Tang Dynasty, originally discovered at God of Wealth Temple in Xiaonanguan Village, Quyang County (Jian, 2021).This Lantern is composed of four white stone carvings arranged vertically into five sections: the base, the dragon-engraved column, the supporting tray, the Lantern chamber, and the roof. Standing at a height of 3.2 meters and a width of 1 meter, the stone amp is intricately carved from Han white jade. The base is square and features a multi-tiered lotus seat atop it. Most decorative patterns have eroded over time, leaving only fragmented remnants. Inscriptions are present on both the front and back sides of the base. However, the characters are blurred. The front inscription comprises 28 lines of varying lengths, concluding with five blank lines. The legible portion of the inscription states: “On the 15th day of the 7th month of the first year of Yan Zai, Sun Sixian of Le’an, Magistrate of Hengyang County under Wenlin Lang of Dingzhou, wrote this”. The rear inscription contains 27 lines, with the content largely unclear, except for the first two lines, which read: “Historian Wei Guolao and Sima Li Zi”. The term “Yan Zai” denotes an era name utilized during the reign of Empress Wu, with character substitutions that were standardized across the nation. Four such substitutions can be identified in the inscriptions: for “month”, “day”, “Zai”, and “year”. Above the base, a dragon pillar features intertwined cloud dragons that ascend around the column, exhibiting robust and vivid expressions. Although the dragon heads have eroded, the scales on the dragon bodies remain relatively well-preserved. The column exhibits a different narrowing, measuring 41 cm in diameter at the base and 37 cm at the top. An octagonal tray, measuring 40 cm per side and 7 cm in height, rests atop the column, supporting a round, upward-facing lotus base that serves as the foundation for the Lantern chamber. This foundation is octagonal and belted, with carvings on the middle of each side, depicting a strongman on the front. The Lantern chamber is a four-sided structure with a pointed roof, featuring doors on the front and back and window openings on the sides, where the frames mimic wooden joinery. The eaves and flying eaves are finely carved, extending 14 cm and 9 cm respectively, with the flying eaves smoothly curved and horizontally arranged. The ends of the eaves are straight and unadorned; the corner beams are simple and square, with 4–5 flying eaves on each corner, predominantly vertical, except for 1–2 near the beam that are slightly slanted. Hidden brackets are carved beneath the eaves, lacking projections, and it appears to feature two medallions. The roof of the Lantern chamber has lost a corner on the front side but remains otherwise intact. The tail end curves naturally, with unadorned ridges, each slope carved with tiles and drip hooks. The pagoda spire, carved from a single stone, appears to be a later addition based on its stylistic and material analysis. As one of the temple’s ritual artifacts, few early stone lanterns have survived to the present day. This Lantern, constructed in the first year of Yan Zai (AD 694), is well-preserved and precisely dated, reflecting certain architectural details reminiscent of wooden structures from a century earlier (Zhang, 1990). The artifact is currently housed in the rear corridor of the north exhibition hall at Beiyue Temple Museum, where it is preserved in a semi-open-air environment.

As shown in Fig. 1, these historical photographs of the stone lantern from different periods carry a wealth of historical information, documenting the migration of the stone lantern from its original storage location to its current position. The current state of preservation of the stone lantern is critically compromised due to extensive weathering. The surface is heavily laden with dust, and most of the decorative motifs have deteriorated significantly, leaving only fragmentary remnants. The inscriptions located on the front and rear sides of the base are largely illegible and exhibit pronounced signs of deterioration and damage; notably, the upper portions of the base corners are missing, and the lotus patterns carved into the base have nearly eroded away. Panlong columns display signs of peeling as a result of weathering, with the scale patterns on the dragon’s body only partially discernible due to severe erosion, and both the dragon’s head and legs are absent. There is considerable rust and crust formation at the base of the column and the lotus-bearing tray. The lantern chamber has experienced the most severe weathering; the surface rock particles are loose and detach upon contact. Two horizontal beams of the lantern chamber are missing, and one column is broken, exhibiting visible repairs from previous restoration efforts; the granularity and flaking due to weathering are apparent. One of the beams has diminished in size as a result of weathering, with widespread hollowing and flaky peeling occurring, and the surface is heavily crusted. The lantern chamber bears a substantial weight from the stupa cover, which increases support requirements and stress, thereby accelerating the weathering process and significantly threatening its stability. The conditions of the roof are complex, characterized by significant black crust formation. Beneath the roof, there are observable hollowing and flaky peeling phenomena, with the roof beams displaying gaps, cracks, and pulverized peeling, in addition to damage inflicted by animals on the upper surface of the roof.

Fig. 1

Photograph of Stone Lantern.

Methodology

Detection and analysis

A comprehensive investigation was conducted on the preservation condition and deterioration types of the Tang white jade dragon stone lantern located at Beiyue Temple. Samples were collected from the lantern, including rock specimens, weathered materials, surface weathering, and surface pollutants. The analytical tests primarily focused on evaluating the physical properties and chemical compositions of the artifacts. Comprehensive analytical testing was employed to diagnose the factors contributing to the lantern’s deterioration and to evaluate its overall condition. Based on these results, scientifically informed restoration strategies were applied.

The instruments used included XRF, XRD, FTIR, and ion chromatography, with the following testing methods:

XRF

To test the oxide composition of the stone samples, they were ground into a powder using an agate mortar and tested using the pressed pellet method, utilizing a Dutch Panalytical Axios X-ray fluorescence tester.

XRD

To test the composition of the stone samples, they were ground into a powder using an agate mortar and tested with a Japanese Rigaku SmartLab SE X-ray diffractometer, using a copper target, with a scanning range of 5–90° and a scanning speed of 10°/min.

FTIR

Powdered samples were treated with dilute hydrochloric acid to dissolve, filtered to obtain the precipitate, and then dried using a vacuum pump filtration. The dried samples underwent Fourier transform infrared spectroscopy testing, utilizing an IS5 type Fourier transform infrared spectrometer with an ATR attachment, scanning from 4000 to 400 cm-1, with a resolution of 8 cm⁻¹ and 128 scans.

IC

The instrument used was a Swiss Metrohm Eco IC ion chromatograph. The conditions for the chromatography column were as follows: injection volume: 25 μL; column temperature: 30 °C; flow rate: 1.0 mL/min; suppressor current: 112 mA; detector temperature: 35 °C; the mass fraction of soluble salt ions was compared to the Austrian technical specification: B3355-1 to assess potential harm to the stone artifacts.

The resultant data are critical for understanding the underlying causes of the stone’s deterioration and for developing effective strategies for the removal of surface contaminants, desalination, and the implementation of weatherproofing and reinforcement measures aimed at preserving the lantern.

The process of cultural relic restoration

3D scanning and disassembly

This stone artifact restoration project combines traditional techniques with modern preservation methods and materials, specifically targeting the scientific conservation of Tang Dynasty stone lanterns. Guided by the principle of minimal intervention, the process begins with 3D scanning to capture precise data, which informs subsequent restoration efforts. The scanning instrument is the EinScan Pro 2X Plus.

Cleaning

The main purpose of cleaning is to remove diseases on the surface of cultural relics and restore the appearance of cultural relics. Due to the special precious value of cultural relics, as well as the irreversibility of cultural relics cleaning operations. In the research and practice of removing the dirt on the surface of stone cultural relics, it is necessary to follow the method of selecting materials from light to heavy (mainly physical cleaning method, supplemented by instrument cleaning method, and avoiding the use of chemical materials as much as possible), the operation process from light to heavy, and the cleaning sequence from top to bottom, from light to dark.

Desalination

The salt content of stone cultural relics determines the weathering speed of cultural relics, and the phenomenon of panning salt will lead to the gradual loosening of the originally stable rock structure until pulverization and peeling off and layer flake peeling, and the salt discharge pulp application operation is carried out on the cultural relics, and the data changes of the conductivity meter are observed and recorded, and the application operation is repeated until the conductivity value area is level, which is completed for desalination.

Infiltration consolidation

The powdered regions of the stone lantern underwent treatment with a chemical reagent infiltration technique for the purpose of consolidation. The selected consolidant, JSY-01, was combined with a minimal quantity of deionized water. This mixture was subsequently applied using a pipette in a drip irrigation manner, and the procedure was repeated three times. This paragraph.

Filling and patching

Due to the serious problem of weathering of stone lamps, the purpose of infiltration reinforcement is to improve the strength and durability of cultural relics, prevent weathering and reduce biological damage. The infiltration reinforcement material selected in this selection is JS-01, and its main components are polyurethane, SiO₂ and TiO₂.

Grouting and full-color application

To mitigate the intrusion of flora, fauna, and microorganisms into the cultural relic and to enhance the stability of the stone Lantern, the application of grouting is essential.

Sealing

The use of JS-01 concentrated solution for the protection of restored cultural relics serves a preventive protection effect, slowing down weathering, resisting pollution, inhibiting biological damage, and thereby extending the lifespan of cultural relics.

Results and discussion

The restoration of cultural relics is carried out using the aforementioned methods, and the restoration is as follows.

Analytical findings

Representation analysis

According to Fig. 2, Sample A is composed of light yellow particles that transition to white upon grinding. Sample B is distinguished by the presence of small yellow particles interspersed with larger white particles; following grinding, the small yellow particles retain their color, while the white particles change to a pale yellow hue. Sample C exhibits a gray-white coloration and is notably brittle, transforming to a bright white upon grinding (Tables 1 and 2).

Fig. 2

Sample macro photograph.

Table 1 XRF test results.

Table 2 Ion chromatography of the sample.

XRD

The three sample components, as shown in the above Fig. 3, are calcite, namely CaCO₃.

Fig. 3

XRD test results.

XRF

The results of X-ray fluorescence (XRF) analysis, as presented in the above table, indicate that Sample A contains several oxides, including calcium oxide (CaO), sulfur trioxide (SO₃), silicon dioxide (SiO₂), iron(III) oxide (Fe₂O₃), aluminum oxide (Al₂O₃), and strontium oxide (SrO). Notably, CaO constitutes 96.58% by mass, followed by SO₃ at 1.34%, SiO₂ at 1.01%, Fe₂O₃ at 0.46%, Al₂O₃ at 0.27%, and SrO at 0.13%. The remaining components account for 0.21%. The predominant constituent of Sample A is CaCO₃, with trace amounts of sulfate (SO₄²⁻) and silica, indicating that the rock is primarily limestone, which appears to be largely unaffected by erosional processes.

Sample B is composed of various oxides, including CaO, SiO₂, SO₃, MgO, Fe₂O₃, Al₂O₃, K₂O, and SrO, with the following mass percentages: CaO 93.76%, SiO₂ 2.25%, SO₃ 1.02%, MgO 1.01%, Fe₂O₃ 0.86%, Al₂O₃ 0.58%, K₂O 0.16%, and SrO 0.13%. Additionally, other components account for 0.23% of the sample. The predominant component of Sample B is CaCO₃, accompanied by minor quantities of silica and SO₄²⁻. This composition suggests that the limestone rock has undergone processes of environmental erosion and weathering.

Oxides in Sample C are CaO, SiO₂, SO₃, MgO, Fe₂O₃, Al₂O₃, K₂O, and SrO. The mass percentages of these components are as follows: CaO constitutes 88.23%, SO₃ 6.47%, SiO₂ 2.34%, MgO 0.97%, Fe₂O₃ 0.87%, Al₂O₃ 0.52%, K₂O 0.19%, and SrO 0.14%, with the remaining constituents accounting for a total of 0.27%. The predominant component of Sample C is CaCO₃, accompanied by minor quantities of SO₄²⁻, silica, and particulate matter. This composition suggests that the limestone rock has undergone significant environmental erosion and weathering processes.

FTIR

Figure 4 depicts the results of the infrared spectroscopy analysis. The macroscopic images and polarized light microscopy indicate that the sample manifests as a crumbly, ochre-colored block that is easily grindable and maintains its ochre hue post-grinding. Following the grinding process, a substantial quantity of rod-shaped material was identified under polarized light microscopy. The infrared spectrum displays characteristic peaks at approximately 3342.77 cm⁻¹, 2917.51 cm⁻¹, 2849.66 cm⁻¹, 1631.23 cm⁻¹, 1380.40 cm⁻¹, 1043.58 cm⁻¹, and 604.69 cm⁻¹. A comparative analysis reveals that these peaks closely correspond to the infrared spectrum of cellophane. Given that cellophane is a natural cellulose derivative, the observation of rod-shaped material under polarized light microscopy implies that the sample is a natural cellulose-based protective film that has experienced aging and degradation.

Fig. 4

Fourier Infrared Spectroscopy Testing Samples and Results of the Panlong Stone Lamp at Beiyue Temple.

IC

The analysis of powdered stone carvings has revealed that the rock contains a significant concentration of soluble salts, including SO₄²⁻, nitrates (NO₃⁻), and carbonates (CO₃²⁻). These compounds pose a continuous threat to the integrity of the stone artifacts and undermine the efficacy of conservation efforts. Additionally, the interaction of water with these soluble salts results in the dissolution and degradation of the rock’s binding components. Consequently, this process leads to the powdering and flaking of the surface decorations of the stone carvings, thereby detrimentally affecting their artistic value (Zhang, 2024).

Illustrates the morphological characteristics of the ion chromatography samples. Based on macroscopic images and observations in Fig. 5, Sample A, which was obtained from the upper section of the western column in the lantern chamber, is characterized by yellow particles that transition to white upon grinding. Sample B, collected from the lower edge on the eastern side of the lantern roof, is identified as a white powder that retains its color after grinding. Sample C, sourced from within the lantern house, initially presents as a white powder that changes to gray, ultimately becoming gray–white following grinding. Sample D, obtained from the lower edge of the western side of the roof, exhibits a gray–white appearance, which remains consistent after grinding.

Fig. 5

Ion chromatography test samples from Beiyue Temple Panlong Stone Lantern.

The ion concentrations in Sample A reveal that SO₄²⁻ is present at the highest concentration, measured at 45.60 ppm. This is followed by calcium ion (Ca²⁺) at 15.23 ppm, magnesium ion (Mg²⁺) at 4.16 ppm, and fluoride ion (F⁻) at the lowest concentration of 0.17 ppm. The concentrations of other ions, including NO₃⁻, chloride (Cl⁻), ammonium (NH₄⁺), nitrite (NO₂⁻), sodium (Na⁺), and lithium (Li⁺), range from 0.99 ppm to 2.51 ppm. Sample A exhibits a substantial concentration of SO₄²⁻, along with minor concentrations of NO₃⁻, Cl⁻, and NO₂⁻, which are likely soluble salts resulting from exposure to acid rain.

Sample B shows the highest concentration of SO₄²⁻ at 8.80 ppm, followed by Ca²⁺ at 6.03 ppm and Mg²⁺ at 2.56 ppm. The concentrations of Cl⁻ are recorded at 2.28 ppm, while NO₃⁻ are present at 1.97 ppm, NH₄⁺ at 1.41 ppm, and F⁻ at the lowest concentration of 0.03 ppm. The concentrations of Na⁺ and Li⁺ are comparable, measuring 1.06 ppm and 0.89 ppm, respectively. Sample B primarily contains lower concentrations of SO₄²⁻, Cl⁻, and NO₃⁻.

The ion profile of Sample C indicates that SO₄²⁻ is the predominant ion, present at a concentration of 332.30 ppm, followed by Ca²⁺ at 94.21 ppm. NO₃⁻ is detected at 3.48 ppm, Mg²⁺ at 3.04 ppm, Cl⁻ at 2.41 ppm, and NH₄⁺ at 1.97 ppm. F⁻ is observed at a notably low concentration of 0.60 ppm, while Na⁺, Li⁺, NO₂⁻, and potassium ion (K⁺) exhibit similar concentrations, ranging from 0.8 to 1.2 ppm. The analysis reveals that Sample C contains a significant amount of SO₄²⁻, along with minor quantities of Cl⁻, NO₃⁻, and NO₂⁻, with gypsum (calcium sulfate (CaSO₄)) identified as the primary contaminant.

Sample D exhibits the highest concentration of SO₄²⁻ at 1197.88 ppm, followed by Ca²⁺ at 293.10 ppm. NO₃⁻ are detected at 4.80 ppm, Mg²⁺ at 2.91 ppm, and Cl^- at 2.59 ppm. Phosphates (PO₄³⁻) are measured at 2.19 ppm, NH₄⁺ at 1.66 ppm, while Li⁺ present the lowest concentration at 0.87 ppm. F⁻ and Na⁺ are closely matched at 1.33 ppm and 1.31 ppm, respectively. The characterization of Sample D reveals elevated levels of SO₄²⁻, which suggests the presence of CaSO₄ corrosion products, alongside minor concentrations of Cl⁻, NO₃⁻, and PO₄³⁻.

Restoration outcomes

3D scanning and disassembly

A 3D scan was performed on all four sides of the cultural artifact utilizing adhesive scanning points. (this phrase should be moved into “Method” section) The resulting post-scan image is presented in Fig. 4. The primary objective of this scan is to preserve the essential data of the original artifact, thereby offering guidance for future virtual restoration and assembly efforts.

In Fig. 6, subsequent to the scanning process, the artifact was disassembled into four primary components: the base, the column, the lantern chamber, and the roof.

Fig. 6

3D scan of Beiyue Temple Panlong Stone Lantern.

In Fig. 7, subsequent to the scanning process, the artifact was disassembled into four primary components: the base, the column, the Lantern chamber, and the roof.

Fig. 7

Dismantling of Beiyue Temple Panlong Stone Lantern for modular restoration.

Cleaning

In Fig. 8, the cleaning process primarily focused on addressing the surface ailments of the stone Lantern, specifically targeting issues related to excessive dust accumulation, thick encrustation, and contamination resulting from human activity. A variety of cleaning methods were employed, tailored to the specific problems identified (Zhang (2023)). Firstly, damage caused by dust was mitigated through the use of brushes, which facilitated the cleaning and unblocking of the artifact’s pores, thereby restoring its breathability. The subsequent detailed cleaning phase involved a combination of techniques adapted to different areas of the Lantern, with particular emphasis on the removal of black contaminants. Methods such as laser cleaning (Zhang, Chen, Zhang, et al., 2024), the application of detergents, steam cleaning (Wang, 2018), and the use of specialized small tools were employed flexibly. Encrustation, identified through analytical methods as CaSO4, was addressed through a combination of chemical and mechanical cleaning techniques. For particularly hard encrusted areas, a 3% ammonium carbonate ((NH4)2CO3) solution was applied using a poultice method. Other regions were treated with brush cleaning, laser cleaning, steam cleaning, and careful scraping with scalpels. Finally, human-induced contaminants, such as graffiti, were removed through laser treatment to restore the artifact’s surface.

Fig. 8

The effect before and after cleaning.

Desalination

Desalination was conducted on four components of the stone Lantern. A desalting pulp was applied to the surface of the carvings affected by salt efflorescence. The water contained in the desalting material permeated the substrate layer, thereby activating and dissolving the saline substances present within the rock. As the water evaporated, the activated salt ions migrated towards the surface and ultimately crystallized within the desalting material. Upon the removal of the desalting material, the salts were also extracted.

Infiltration consolidation

The powdered regions of the stone lantern underwent treatment with a chemical reagent infiltration technique for the purpose of consolidation. The selected consolidant, JSY-01, was combined with a minimal quantity of deionized water. This mixture was subsequently applied using a pipette in a drip irrigation manner, and the procedure was repeated three times. This paragraph.

Filling and patching

In Fig. 9, the photograph presents the comprehensive restoration process of the cultural relic, which is notably missing two significant components: one located at the two horizontal beams of the stone Lantern chamber and another at one corner of the stone Lantern roof. For the restoration of the Lantern chamber, an original stone heteromorphic splicing technique was employed. Initially, the shape of the absent heteromorphic surface was generated using ZB software, followed by preassembly utilizing 3D printed models. Subsequent adjustments were made, after which original stone carving was executed, culminating in the application of epoxy resin for bonding. In addition to the aforementioned technique, the restoration of the Lantern roof incorporated anchor rod technology to enhance structural stability. Following pre-assembly, anchor rods were embedded into the original stone, and the final bonding was achieved using epoxy resin.

Fig. 9

Replenishment flowchart for restoration of Beiyue Temple Panlong Stone Lantern.

Grouting and full-color application

In Fig. 10, a pure solution of JSY-01, combined with homogeneous stone powder, is utilized to formulate a mortar for the grouting process. Following the completion of grouting, traditional full-coloring techniques are employed on both the restored and grouted areas. This approach results in an appearance that is uniform from a distance while remaining distinguishable upon closer inspection (Duan, 2019).

Fig. 10

Hook seaming and touch-up performance for restoration of Beiyue Temple Panlong Stone Lantern.

Sealing

For the conservation of cultural relics after repair, the JS-01 stone maintenance liquid is to be applied comprehensively.

Assembly and effect display

Figure 11 depicts comparative images depicting the state of the cultural relic prior to and following assembly, as well as before and after restoration. Upon completion of the restoration process, the stone Lantern was reassembled utilizing a combination of a crane, pulley systems, and rolling logs (Geng, 2022). The restored components, including the columns, Lantern chamber, base, and roof, were reassembled in accordance with the initial positions obtained from 3D scanning conducted previously.

Fig. 11

Assembling process and cultural relics restoration performance for Beiyue Temple.

Conclusion

This restoration undertaking was able to lap modern conservation technologies with traditional craftsmanship techniques, using these synergistic approaches to restore the Tang White Marble Panlong Stone Lantern located at the Beiyue Temple. The restoration was achieved using systematic 4D scanning, analytical testing through X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectrometry, and ion chromatography, and tailored interventions—a combination of approaches that mitigated the most pressing deterioration issues without compromising historical value. Innovative consolidation and weatherproofing were achieved with specially formulated JS-01 penetrating reinforcement material (Fig. 12).

Fig. 12

Comparison of the effect before and after the repair.

Despite the significant advances made, some shortcomings must be noted. First, the effectiveness of the long-term consolidation remediation with JS-01 will need to be subjected to ongoing scrutiny due to inadequate understanding of performance in different environmental conditions. Second, the use of virtual reconstruction as a restoring tool while aiding accuracy within original sections retained in the artifact generated tensions over visual fidelity. Third, the successful outcome of the desalination process will become subject to the need for regular exposure retreatment as the environment remains uncontrollable. Lastly, the proposed restoration method may not be suitable for other artifacts that possess different compositions of materials or patterns of deterioration.

Further conservation work should focus on designing and implementing an active monitoring plan tailored to the lantern’s conditions, developing high-quality materials that are less invasive and more sustainable for the preservation, and creating precise documentation procedures to inform other subsequent preservation actions.