Glass is manufactured through the Pilkington process. Raw materials like sand, calcium oxide and sodium carbonate are weighed, mixed and heated to form molten glass. This molten glass is then floated on molten tin to create sheets of uniform thickness. The glass is then annealed by controlled cooling. There are different types of glass including float glass, which is the most common, as well as processed glasses like tinted, wired, laminated, toughened, and reflective glasses. Processed glasses undergo further thermal or chemical treatments to modify their properties. Double glazed units provide insulation and energy efficiency. The differences between float glass and toughened glass will be explored further in part 2.