The chemical interactions that occur between tin and molten glass during the float forming process were investigated using experimental techniques & theoretical modeling calculations. The characteristic bump in the tin penetration profile commonly observed in the bottom side of green commercial float glasses was reproduced in laboratory float experiements. Thermodynamic modeling calculations revealed the existence of a steep gradient in the oxygen activity between the highly-reduced tin bath & the relatively oxidized float glasses. The tin penetration profiles of two high-iron glasses floated in the laboratory were deconvoluted into Sn2+ & Sn4+ components, according to the proposed oxygen activity gradient. Accdording to the calculations, the bump in the tin profile is associated with the accumulation of Sn4+ in a localized region.
