Quartz sand, soda and lime are placed in a large container where they are finely ground and mixed together. This mixture then goes into a glass kiln, where it is heated to a temperature of 1400 to 1600°C. This causes a chemical reaction that creates a soft, sticky mass full of bubbles, which is cooled down to about 1000°C for the further processing.
Impurities in the raw materials cause the glass to be cloudy, so manganese dioxide is added to obtain a clear, colorless mass. The manganese dioxide neutralizes the green and brown coloration produced by the sand's iron content. Colored glass is made by adding a range of metal oxides to the molten glass, and other coloring's in microscopically fine forms can also be distributed in the glass mass. Cloudy glass can be made by using additives such as calcium phosphate, tin dioxide and cryolite. Common treatments for glass after it has been formed into a shape include polishing, sandblasting and etching.