Transformation of plant-based tempers (Grog): evolution and techniques in Songze, Liangzhu, and Guangfulin pottery

The utilisation of plant-based temper in Songze culture pottery incorporated a substantial proportion of fibre and exhibited a microstructure resembling a fully oxidised rice husk temper (Grog). However, during the Liangzhu and Guangfulin periods, these plant-based tempers underwent a transformation into quartz and other mineral tempers. Notably, amphibole tempers were identified in pottery from the Liangzhu culture, particularly in black pottery coatings. The structure of the low-aluminium ceramic coating was determined to be porous, and initially, this type of temper was thought to be debris resulting from jade processing. However, experimental archaeological studies have demonstrated that it is difficult for jade fragments to develop a similar petrographic structure. In pottery from the Guangfulin culture, white pottery coatings turned black when compacted. This colour alteration may have been achieved through simple sintering processing, suggesting the potential utilisation of a two-step pottery processing technique under low-fire conditions.