Systematic pre-oxidation experiments in the glass transition region have been carried out on iron bearing aluminosilicate glass fibres in air. The pre-oxidized fibres are up-scanned ina simultaneous thermal analyser to a temperature of 1273K under atmospheric conditions in order to measure the increase in mass, which is a consequence of the oxidation of ferrous iron to ferric iron. Based on the Mossbauer spectroscopic measurements, an approach has been proposed to calculate the redox state of the iron from the increase in mass of the fibres. The quantitative relationships have been found between the redox state of the fibres and both the pre-oxidation temperature and the pre-oxidation duration. These relationships can be used to predict the degree of oxidation of the fibres by knowing the heat treatment conditions and vice versa.
