The formation of pseudowollastonite for frit PF begins at 8501C, corresponding to the onset of the first crystallization peak in the DTA plot (Fig. 3). A significant increase in the peak intensity for wollastonite at 9251C is visible. This temperature is in agreement with the onset of the second crystallization peak in the DTA plot (Fig. 3). At 11001C, the peak intensity of the pseudowollastonite decreased, most likely due to the solubilization of this crystalline phase in the glassy matrix. However, the peak intensity of the crystalline phase increased again at 11451C due to the polymorphic conversion of wollastonite to pseudowollastonite that occurs approximately 11271C[21,22].