Silica in the form of sand is the main ingredient of glass, and this (combine) with soda ash and limestone in special pots which (place) into the furnace. Broken, recycled glass known as 'cullet' (add) to the ingredients to speed up the melting process. Other materials can (add) to produce different colours or properties. For example, adding the minerals cobalt or sulphur will produce coloured glass. While it is still molten (a hot liquid), glass can (manipulated) by glass blowers to form bottles and other decorative articles. They blow air into the liquid glass through a long pipe.
Glass (make) since the times of the Ancient Egyptians, about 3000 years ago. The Egyptians made glass beads and used them as jewellery.In factories today, bottle blowing machines produce bottles and jars by pressing and blowing the molten glass inside a mould. Flat glass (make) by floating the molten glass onto flat beds of tin. Glass can also be coated, heat-treated, engraved or decorated. It (use) to make optical fibres for use in medicine and for parts for modern communications.
NATURALLY FORMED GLASS
The glass (throw) into a recycling bin by the customer. Glass (take) from the bin to a glass treatment plant. The glass (sort) by colour and (wash) to remove any impurities. Then, the glass (crush) and (melt)After that it (mould) into new products such as bottles and jars. Or it may (use) for alternative purposes such as brick manufacture or decorative uses. The glass (send) back to the shops ready to be used again. Glass does not degrade through the recycling process, so it can (recycle) again and again .
