1. INTRODUCTION
2. RESEARCH SUBJECTS AND METHODS
2.1. Research subjects
2.2. Research method
3. RESEARCH FINDINGS
3.1. Microscopic examination
3.2. Polarizing microscope research
3.3. Crystal phase analysis (XRD)
3.4. Microstructure and chemical composition analysis (SEM-EDS)
3.5. Thermogravimetric-differential scanning calorimetry (TGA-DSC)
3.6. Micro-computed tomography
3.7. Laser particle size analysis
4. DISCUSSION
5. CONCLUSIONS
1. The lime plaster had two or more layers; the layers’ thickness ranged from approximately 1.6 to 4 mm; and there were differences in the layers’ physical properties, such as their color, mixture distribution, and density.
2. The primary mineral component of the lime plaster was calcite, and other minerals, such as quartz, mica, and feldspar, were detected in trace amounts, while some dolomite particles were observed in the lower layer. Most particles were fine particles.
3. Chemical analysis of the lime plaster detected Si, Al, and Mg, indicating that soil-based materials were mixed with the plaster. However, microscopic observations confirmed that very few presumed soil particles were mixed. Therefore, unlike the common production style found in the walls used for mural paintings in Goguryeo tombs—wherein soil-based materials were mixed with lime plaster—almost pure lime plaster was used for Anak Tomb No.3. Nevertheless, the soil components detected in this study suggest that some white soil materials, such as kaolinite, were mixed with the plaster.
4. Considering the pores found inside the lime plaster, density of the finish layer, and traces of applications on the surface of the sample, the lime plaster was prepared and used under conditions conducive to the production of a mural by accounting for the consistency of the plaster and its solidity when hardened. Therefore, the whiteness, durability, thinness, and repetition of the layers, as well as smoothness of the lime plaster used for Anak Tomb No. 3, indicate that a high level of lime wall plastering technique was used.