Being inspired by nature, a series of experiments was carried out to deposit a calcium oxalate layer on the surface of the stone by the reaction between carbonate rock and oxalate salt. To increase the anti-dissolution properties of the calcium oxalate layer, the use of mixed oxalate solution has been proposed in the literature by two main routes: (1) adding acid agent to ammonium oxalate, which has the advantage of changing the particle structure and reducing layer porosity, and (2) using neutral methyl oxalate solution, which has the advantage of surface coverage due to slowly hydrolysis. In this study, we investigated the sequential application of ammonium oxalate, methyl oxalate, neutral mixed, and calcium acetate acid mixed solution. With this method, calcium carbonate and calcium oxalate solution can react inside the stone to reinforce it. The protective film’s coverage area can then be increased using dimethyl oxalate neutral mixed solution, and the crystal morphology can be modified with calcium oxalate acid mixed solution. The anti-dissolution properties of the coating were investigated using both a custom-designed apparatus and a selective outdoor environment. The coating displayed good acid resistance properties at pH 2–4. After one year of exposure, the coating is firmly bonded with the stone.
The fuel residues in two bronze lamps excavated from Haihunhou Tomb in the Han Dynasty, in Jiangxi Province, China, were studied in this paper. The techniques of Fourier transform infrared (FT-IR) spectroscopy and pyrolysis-gas chromatography-mass spectrometry with thermal-assisted hydrolysis and methylation (THM-Py-GC/MS) were used to characterize the materials. Long-chain fatty acids, fatty alcohols and hydrocarbons were detected as the main components. By comparing the reference materials of beeswax and Chinese wax, the residues in the lamps were identified as beeswax. Furthermore, according to the morphology of the remains of the lamp fuel, the fuel remains were probably melted and then solidified, which suggests the lamps were used. Wax was found to have been used as an illuminating fuel as early as the Han Dynasty, enriching scholarly knowledge about the lighting materials used in ancient China.
The deposition of a calcium oxalate layer on dolomite demonstrates potential application in stone culture heritage conservation. However, due to insufficient coverage and the presence of cracks, the film’s usefulness is restricted. In this investigation, we used a simple two-step procedure to create a cohesive and uncracked film. The findings show that the protective layer provides better coverage of the dolomite surface without causing cracks and significantly improves acid resistance. Furthermore, after the simple two-step treatment, the color and adhesive strength of dolomite substrates remained nearly unchanged.
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