How glass bottles are made

At the beginning, glass ia made from sand, limestone, and soda ash. Then, these three materials are mixed together in the right proportions. Third, sometimes broken glass is added. Forth, this mixture are heated strongly in a furnace. And then, glass is produced. After that, it is shaped into bottles in the mould. Sixth, the bottles are reheated and cool to strengthen the glass. Finally, they are ready to be used.