Unveiling Float Glass Staining Induced by an Acid‐Cleaning Product

ABSTRACT Staining of glass facades is a recurring and significant problem worldwide. This study investigates the causes of staining observed on six laminated float glass samples from four manufacturers (α, β, γ, and δ). Samples from β, γ, and δ were new, whereas those from α (α 1 , α 2 , and α 3 ) were taken from a building after service exposure. Staining of α 2 , α 3 , and δ was observed after exposure to an acid‐cleaning product for at least 30 s. Our investigation focused on tin concentration and oxidation state at the glass surface, the overall chemical composition, and surface condition as potential factors associated with this behavior. Extensive characterization using multiple techniques revealed small amounts of tin on the outer face, with the highest content in α 3 . However, neither tin concentration nor its oxidation state showed a clear correlation with the staining pattern, as α 2 and δ had much lower tin levels. The staining observed for the unused δ glass is attributed to its higher modifier content relative to network formers and lower chemical durability. In contrast, the staining observed for α 2 and α 3 appears to be related to surface damage, in which micro‐scratched surfaces undergo a rapid increase in roughness upon chemical exposure and become more susceptible to visible staining, whereas well‐polished surfaces remain largely unaffected. These results indicate that chemical durability and surface condition are important factors influencing the susceptibility of float glasses to staining.