As noted previously in our blog, the Romans began to use glass for windows around the first century. Stained glass windows did not come around until the 12th century and were predominately seen in churches and other beautiful edifices. However, by the seventeenth century, windows began to be used in European homes and cottages. At that time, windows were formed by creating small panes separated with wood, or lead piping. Today, glass windows are found throughout the entire home. Large glass sheets are mass-produced with automated processes that ensure quality and consistency. Although the way glass windows are produced has changed, the main ingredients generally remain the same. Limestone, soda ash, and silica sand are mixed and poured into a furnace with soft, malleable tin. The heavier tin sinks to lay down perfectly flat while the other minerals naturally separate to form a flat layer of glass. The glass is then allowed to cool slowly and is cut into desired sizes.