So-called minor constituents of glass, e.g. those which can exist in more than one valence state, have played a major role in glass technology. Many are used to colour glass while others, such as arsenic and antimony oxides and sulfur, play an important role in refining glass. Iron, considered to be one of the most important of these minor constituents because of the generally unacceptable colour that it imparts to flint glass, has been the subject of many investigations. Previous redox research has answered many questions for the glass industry with regard to the action of oxygen and elements as they affect our final product. This history of this research is essential to future research, and much-needed solutions to the problems that glassmakers will continue to encounter.
