There are several ways to determine
the volume of a mould.
Calculation of the weight of glass needed
Calculate the
amount
in the metric system of measures, as that gives much easier calculations. Cubic
centimetres of volume times the specific gravity of glass (2.5) will give you
the number of grams of glass required.
This
works best on regular geometric forms.
Rectangles and parallelograms are easy to measure the length, width and
depth in centimetres. Multiply together
and you obtain cubic centimetres. That
times the specific gravity – 2.5 – will give the number of grams to fill the
mould. The frit will of course be
mounded above the levelled surface, because of the air spaces between the frit
pieces.
Irregular shaped moulds
The
moulds which are irregular in shape or depth are more difficult to
calculate.
You
can determine the volume by starting with a measured amount of water. Quickly fill the mould to the surface, so
that no water is absorbed into the mould. Empty the water from the mould into
the drain so it does not become soaked. The difference between the starting and
finishing amount of water is the volume of glass required to fill the mould.
You
can use that volume in cubic centimetres times the specific gravity (2.5) to
get the number of grams of glass required.
However,
it is much easier to put the frit into the water until the measure shows the
same amount as before the mould was filled. Then you only need pour off the
water and allow glass and mould to dry.
No calculation required.
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