Iron oxides (Fe₂O₃) are the first enemy of glass clarity. Above roughly 0.030%, they give clear glass an unwanted green tint that becomes obvious at the edges of a sheet.
That is why global glassmakers enforce strict iron limits on silica sand. Knooz Watad supplies its clear-glass grade at no more than 0.030% Fe₂O₃, achieved through advanced magnetic separation and washing — which is what keeps colour consistent from shipment to shipment.