GLASS

Romen cage cup from the 4 th century
A.D

A super cooled liquid made mainly form sand, glass is easily shaped, and forms clear, hard objects that remain untainted by chemicals. Glass objects are often mass-produced by the moulding process, in which jets of compressed air force molten galss into the shape of a mould. Sheet glass is made by the float-glass is made by the float glass process, in which molten glass is floated on the surface of liquid tin and cut into lengths when cool.