Thus a
grey clay may burn a rich red or pale cream. The qualities necessary in
clay for modelling are plasticity, which enables it to be worked without
falling to pieces, and fineness--a perfect freedom from grit, small
stones, and other impurities. It should be quite soft to the touch, and
when pressed and kneaded should feel smooth and silky. Old clay is more
plastic as well as being tougher than new, and in potteries clay is
often kept a considerable time before it is used. The clay should not be
allowed to dry when it is not in use, and to prevent this it must be
wrapped in wet flannel. Should it dry quite hard, there is nothing to do
but to put it into a vessel and pour water on it, allowing it to stand
until the clay becomes soft. Some of the moisture must then be allowed
to evaporate, otherwise it is too soft for use. This is another point to
be observed in clay used for modelling. It must not be too damp. If it
sticks to the fingers it is too wet, and if it resists the pressure of
the fingers, too dry. The state between stickiness and stubbornness is
what is wanted.
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