For frit CF, wollastonite crystallized at 9251C, as shown in the DTA plot. The maximum peak intensity occurred at 10001C. This result was expected because the viscosity of the liquid phase was lower at 10001C, providing better conditions for crystal growth [12]. As observed for frit PF, the peak intensity for frit CF decreased from 11001C with the onset of fusion, which was identified in the heating microscopy plot (Fig. 3). At 11451C, a polymorphic transformation of the small remaining amount of wollastonite occurred, resulting in a small increase in the pseudowollastonite peak.