Glass....its history... different uses.....and manufacturing process.....

1. GLASS

2.  Glass is an amorphous solid material that
exhibits a glass transition, which is the reversible
transition in amorphous materials from a hard
and relatively brittle state into a molten or
rubber-like state.
 Glasses are typically brittle and can be
optically transparent.

3. THE BIZARRE PROPERTIES OF GLASS
IS IT A SOLID OR A LIQUID?
 Despite the solid appearance, glass is actually
in a ‘jammed’ state of matter.
 It is somewhere between liquid and solid.
 It has random un-oriented
molecules as opposed to
a crystal solid with
arranged fixed molecules.
 It moves very slowly and
never quite becomes
a proper solid.

4. HOW GLASS IS MADE….?
 Glass is a made by melting a mixture of sand and other minerals in a
furnace at temperatures of 1700º Celsius (3,092º F).
 Silica in the form of sand is the main ingredient of glass, and this is
combined with soda ash and limestone in special pots which are placed into
the furnace.
 Broken, recycled glass known as 'cullet' is added to the ingredients to
speed up the melting process.
 Other materials can be added to produce different colours or properties.
For example, adding the minerals cobalt or sulphur will produce coloured
glass.

5.  Glass has been made since the times of the Ancient Egyptians, about 3000 years
ago. The Egyptians made glass beads and used them as jewellery.
Roman Cage Cup from the 4th century AD Ancient Greek glass amphora from
the Hellenistic period.

6. Some other things made with glass
Aquariums
Engraved glassware
Test tubes

7. Stained glass window panels

8. Also used in making mirrors, ornaments, car windsheilds, building
exteriors and interios etc.,

9. Naturally formed glass
Obsidian is a naturally formed glassy stone. It forms when sand shoots out of an erupting
volcano. It melts in the volcanic lava and when it comes into contact with water it cools
quickly. The glass is dark green to black. Obsidian has been used by ancient peoples since
the Stone Age, as a cutting tool, for tips for spears, and for ceremonial purposes.

10. THANK YOU…..