Sheet Glass
Since first half of the 20th Century, sheet glass has been made by rolling or drawing. Rolling involves passing molten glass from a tank furnace over a refractory lip and between rollers. In contrast, drawing involves dipping a metal plate into a bath of molten glass and slowly withdrawing it – the glass is passed between two coolers to stop it necking down to a ribbon. There were three types of drawing that, by the mid-1900s, were responsible for the entire global production of flat glass: Fourcault, Pittsburgh and Libbey-Owens.
