"
"What are the moulds made of?" was Theo's first question.
"I am glad you asked, for that is the vital matter," Mr. Marwood
replied. "Many materials have been tried with varying degrees of
success--plaster-of-Paris, alabaster, steel, gun-metal, and brass. Of
course what is necessary is a strong, firm, absorbent material. Clay
moulds break too easily, and also become saturated with water and lose
their shape; metal moulds, on the other hand, while most useful in
making wares decorated with fine, raised designs such as the Wedgwood
figures, fail to seep up the superfluous water. Therefore
plaster-of-Paris has proved the best medium for the purpose. Not only
does it retain its form, but it also takes up a certain proportion of
the moisture from the clay that is moulded inside or outside it."
"I understand," Theo nodded.
The elevator stopped and they stepped out into a vast, well-lighted
room, gray with clay-dust and thronging with powdery workers. At
benches, before revolving wheels, and beside turning-lathes toiled
busy workmen with white, clay-coated hands.
"We will start our program with the potter's wheel, the oldest of
pottery modeling devices," said Mr.
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