Glass is made from a mixture of common
chemicals: silica, lime and soda or potash. These chemicals
are dried and then heated together, a process known as fritting.
The frit is then placed in pots in a chamber
above the furnace. The heat melts the frit to produce glass.
Once the bottles etc had been blown they
then had to be cooled very slowly (annealed) to stop them cracking.
It was then converted into a pottery kiln,
with the floor level being raised and small pottery kilns being
built inside during the 19th century. In about 1870 a railway siding
was built to connect the pottery with the docks.
The Glass Cone was last used in 1939. It was
demolished in 1943, excavated 1975-76, and consolidated in 1985.