Page 30 - Curriculum Visions Dynamic Book

the Beth She’arim cemetery in Galilee, Israel, in the 4th century a.d. The glass slab found here was abandoned after it had been made and is still intact thousands of years later. It is nearly 3m long and weighs 9 tonnes.
To produce this slab would have needed probably 20 tonnes of wood fuel and 11 tonnes of sand and lime. The whole mixture would have been fired in a pit and might have taken 10 days to melt and form.
The slab would have provided the glass for tens of thousands of drinking glasses or bowls.
Cast glass
The first glass was all cast. That is, it was melted and then poured into a mould,
or ground glass was heated in a
mould until it melted. This produced only solid objects. It could not, for example, result in a bottle. To make
a bottle, the glass had to be formed around a solid object called a core (see opposite).
Whether solid or hollow, the surface would have been very rough because it would have taken on the surface texture of the clay mould.
Glass cast in this way therefore
had to be smoothed, for example, by rubbing it with pieces of sandstone rocks. Some glass was smoothed and polished by turning it on a lathe. It was all hard, time- consuming work.
The labor and time that went into glass meant it was a precious material and only available to the wealthy.
Moulded glass
By 100 b.c. people had discovered how to press molten glass into a mould and so get it to take on the shape of the mould.
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(Below) The Egyptians had mastered the art of core forming by the middle of the 16th century b.c. (see opposite). This vase belongs to the 18th Dynasty, around 1400 to 1300 b.c. It is about 11cm tall.