Glasses and the art of making it have been known for centuries. From beautifully- made stained glasses in medieval churches, to ancient containers for perfume and oil, to glass covered skyscrapers, glass has become indispensable in almost every facet of life.
The use of glasses has been wide range because of its properties. It should be taken into consideration that glasses are transparent to visible light (perfect as windows, drinking objects and reaction viewers), not that reactive to chemicals because it is a ceramic (use in chemical reaction and laboratory processes, cooking), they have no distinct melting or freezing points (perfect for containment) and they are inorganic (do not decay). Because of this wide range of usage, it is important for future engineers to have knowledge of how glasses are produced.
The process of glass making is quite simple and one-way. First, the furnace collects the raw materials – cullet (recycled glass rejects), soda, lime, sand and other additives and then melts all these materials. After melting, they are molded into shapes preferred by the producers. The glass containers are then placed in a special oven called the Lehr to be annealed. Annealing makes the glass containers harder but more brittle. After annealing, the glass containers are coated with a polyethylene wax to make it slippery, thereby protecting it from scratches. After which, the glass containers are thoroughly inspected by machines. Rejects are recycled back into the furnaces. The last process in glass making depends on the preferences of the customers. Glasses can be filled, packaged empty, or colored.
This activity mimicked this entire process into a smaller model, which can be easily understood by students. Implicitly, the activity showed how important glass is and how profitable glass making industry is.
