Based on the patent information, scientific literature, and research done by the Saratov Institute of Glass, the effect of additives and impurities in tin on the quality of float glass is determined. The mechanism of an effective metallic additive is clarified. An activity progression of impurity components in tin with respect to oxygen and sulfur is arranged, and on its basis it is possible to estimate and predict the effect of the additives on the reactions between tin and glass and control the glass quality.