Sample S3-P-L2-01:The outer layer of the plaster from the door framewas similar to the composition of L2 from the Entrance Hall. Finer aggregate was noted in the lime plaster mixture, and thin fibres had also been incorporated into the mix. Sulphur was also detected, but results are not yet conclusive about the source of gypsum (intentional addition or pollution product). 2.1.1Fibre analysis of regular plaster samples Two types of fibres were present in the samples: loose, light yellow, fine fibres (Type A shown in Figure 10) and thick, bundled fibres with a yellowish golden color (Type B in Figure 11 and Figure 12). Type Bfibres were not well dispersed in the mixture but were instead concentrated in one location (shown in Figure 12). Fibre analysis with Polarized Light Microscopy (PLM) indicated that Type A Figure 9(a).Representative fragment of outer plaster layerfrom archway at Service 3. Sample name: S3-P-L2-01. (b).Photomicrograph of the polished surface of fragmentfrom (a).
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Pun Uk Mansion –Preliminary Investigation of Architectural Finishes –Architectural Conservation Laboratory HKU Faculty of Architecture - July 2018 8 (present in sample S3-P-L2-01) is likely ramie (Figure10) and Type B (presentin samples EH-P-L1-02 and EH-P-L2-01) is likely jute (Figure 11 and Figure 12). Jute fibres were minimally processed and appear as a “stem” rather than individual fibres. These “stems” were mashed with a mortar and pestle to separate the fibres for individual evaluation. After this mashing, many fibre cells with scalloped edges were noted, which is characteristic of jute. Figure 10.Type ALongitudinal section of fibres from the outer layer of the plaster debris from the archway at Service 3 (S3-P-L2-01). Tapering and pointed or rounded cell ends can be seen. Transverse dislocations are present. No bifurcated ends were observed in the sample. The width of the fibre varies. The lumen is thin and not always apparent. Figure 11.Type BLongitudinal section of stem fromthe inner layer of the plaster from the Entrance Hall (EH-P-L1-02). Rhombic crystals (teal outline) werefound.