No abstract

In recent years, 3D technology has been widely used in various aspects of the entire workflow of conservation–restoration. However, in the majority of cases, researchers have mainly relied on 3D technologies to assist the conventional conservation–restoration process, and its advantages have not truly been exploited. In this paper, we applied a combination of digital acquisition, virtual anastylosis, virtual reconstruction, and 3D printing of a transparent reversible prosthesis with slots for the restoration of a gold foil decorated Black Ding bowl collected by the Chifeng Museum of the Inner Mongolia Autonomous Region. While completing the physical/aesthetic restoration of the artifact, the conservation–restoration principles of the integrity and authenticity of cultural heritage, minimal intervention and reversibility were followed to the utmost extent. At the same time, we also conducted preliminary performance tests on the 3D printing material of the prosthesis, and the results showed that the material has excellent mechanical properties and stain resistance, contributing to the long-term, stable preservation of the artifact. This work presents an innovative solution applicable to other pieces of cultural heritage and has high significance for promotion.

The origins of composite tiles, one of the oldest forms of roofing, are still unclear. This study is based on a set of over 5000 clay tile fragments excavated from a single context in the Qiaocun site on the Chinese Loess Plateau, dated to ~ 2400–2200 BCE (Early Longshan Period). By combining morphological measurement statistics, 3D modeling, computer-based simulations, and reference to historical and archaeological records, we reconstruct the earliest known composite-tile roofing techniques and demonstrate that tile production was under a low-level standardization, with manual control forming a key agent during the roofing process. The quantitative study of the composite roof tiles from Qiaocun was then placed in its archaeological context and compared with other sites on the Loess Plateau. It was found that tile-roofed buildings were, by necessity, community projects. Such structures served as nodes in larger social communication networks; additionally, their appearance was linked to intensified social complexity in public affairs during the Longshan Period. The invention of clay tiles was associated with the inception of thick rammed-earth walls which had sufficient strength to serve as load-bearing structures for heavy tiled roofs. The roof tiles excavated from Qiaocun site indicate that the Loess Plateau was a key center for the origin and spread of composite tiles and related roofing and construction methods, suggesting a Longshan–Western Zhou tradition of roofing techniques in East Asia.

In recent years, with the excavation of an increasing amount of gold and silver artifacts, there has been an urgent need to optimize the formulations and methods of metallographic etching. Herein, a kinetic control study is performed to investigate the mechanisms leading to poor results when etching ancient gold materials with aqua regia, i.e., when secondary AgCl impurities form during the etching of the sample surface. To this end, a concentrated ammonia and sodium thiosulfate solution is used to dissolve AgCl impurities and obtain high-quality metallographic images of ancient gold materials using a coordination reaction to generate stable free-state coordination ions from Ag+. On this basis, a ferric chloride + sodium thiosulfate method is proposed to optimize the formulation of the etchant for ancient silver materials. The formulation is efficient, safe and easy to handle, and solves the problems of the easy failure of the commonly used etchant of ammonia + hydrogen peroxide and the complicated preparation process of acidified potassium dichromate while maintaining the long-term stability of the etched Ag–Cu alloy samples.