"
"You spoke, Mr. Marwood, of casting some wares," remarked Theo.
The older man smiled.
"You have a good memory, my boy," he said. "I did mention casting. It
is an independent process, and shapes of great variety can be
fashioned as well as ornamented in this way. By the casting method,
too, we are certain of getting articles of uniform thickness. We can
even make very thin objects by this means. But the process is
destructive of moulds, and therefore has its flaws. The success of the
plan is entirely dependent on the mould's absorption of the moisture
in the clay; otherwise the method of casting could not be applied to
potteries or porcelains. As the clay is compressed the water is
squeezed out of it, and this the mould must take up, or the clay would
never dry and retain its shape. You can understand that, I think."
"Yes, sir."
"The last of the processes of which I wish to tell you is
die-pressing. Here we take a very finely ground clay dust; moisten it
a little; and fill a die, or steel mould, with it. This die we then
put into a screw, or hydraulic press, and squeeze it under an intense
pressure with the result that the piece is shaped very solidly.
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