Spectroscopic techniques for the determination of the iron redox state of glass and their direct application in the glass factory

Some preliminary investigations are described in this paper to check whethe r the daily controlling of the redox state of glass carl be performed direc tly in the glass factory using complementary techniques such as spectrophot ometry and photoluminescence spectroscopy. The advantage of spectroscopic t echniques with respect to the traditional wet chemical method is speed and simplicity of the measurement procedure (no specialised operators are requi red) once the whole procedure has been well established However, the chemic al method remains the absolute reference one to be used in cases of difficu lt interpretations (sudden variation of the redox state, unpredictable pres ence of other chromo- phores etc.) or when initial calibrations of the spec troscopic techniques are required. These calibrations should be performed u sing glasses produced by the same factory with the highest possible variati ons in ferrous and ferric iron concentrations.