Raman analysis of glaze on various archaeological shard samples and intact Ming plates

Raman microscopy is used in the analysis of glaze on a number of samples that include blue and white ceramic shards, a tile from the Citadel of Algiers and intact Ming plates. The use of the glaze depth profiling method for the study of interfacial pigments on these samples [J. Raman Spectrosc. 2007; 38: 1480] prompted the study of the glaze on the same set of samples to determine glaze type dependence of this method. Using the index of polymerization ( I p ) which is closely correlated with glaze composition and processing temperature, it is shown that processing temperature could be estimated from a low of about 600 °C for some of the unknown archaeological shards to about 1000 °C or above for the Ming porcelain shards. Two intact porcelain plates from the Hongzhi (1488 – 1505) and Wanli (1573 – 1620) Ming imperial periods from the J. A. van Tilburg Museum of the University of Pretoria have been studied, and glaze/glass transition temperature was estimated to be above 1000 °C, consistent with historical data. A SnO 2 ‐based glaze tile shard from the Citadel of Algiers was also successfully probed, and results indicated a much lower sintering temperature.