Porcelain glaze defects can originate on cups and dishes during fast-firing processes due to formation of bubbles. Raman microprobe techniques have been used to analyze the gas contents of such bubbles along with determining the structural nature of solid inclusions found on the surface of or near the bubbles. Spectral data clearly indicate that the gas contents of these bubbles contain atmospheres comparable to air, along with possibly excess carbon dioxide, depending upon firing conditions. Investigated solid inclusions contain α-quartz and/or α-cristo-balite.
