soda–lime glass is divided technically into glass used for windows, called flat glass, and glass for containers, called container glass. the two types differ in the application, production method (float process for windows, blowing and pressing for containers), and chemical composition. flat glass has a higher magnesium oxide and sodium oxide content than container glass, and a lower silica, calcium oxide, and aluminium oxide content. from the lower content of highly water-soluble ions (sodium and magnesium) in container glass comes its slightly higher chemical durability against water, which is required especially for storage of beverages and food.