The production of pottery by hand is a form of modeling but with the
important difference that while pieces modeled by art-school methods are
not intended to be preserved in the clay itself, built pieces are
destined for the fire. It is therefore necessary not only that a special
clay be used but that the work be such as will hold under the strain of
the burn. The composition of the clay has been dealt with in another
chapter and it is presumed that the worker has decided upon the proper
mix or has procured a suitable clay.
There are two possible treatments of built pottery; the work may be
finished by fingers and tools only or it may be placed upon the wheel
and turned to a true surface. In the latter case the result is much the
same as if the piece were thrown on the wheel as will be described. The
principal point of difference is that while building needs less practice
than throwing, turning a built piece is much more difficult and tedious
than turning a thrown one. It is almost impossible to build with
sufficient accuracy for the work to run true, and a great deal of time
is consumed in filling hollows and removing lumps. These do not appear
obtrusive when the work is held in the hand, but if it be revolved upon
a fixed center every slight irregularity appears to be accentuated. On
the other hand the charm of built ware lies in the subtle plastic
quality which belongs to no other material or method.
For very large pieces such as tree pots the combination method is useful
but these should be built on the wheel itself and kept true as the work
proceeds. Then a slight turning at the finish, when the clay is leather
hard, will produce a satisfactory result.
The clay for building should be rather soft as it is apt to dry quickly
on handling. The work may be done either with coils or pieces.
A plaster bat should be made with a low dome in the center. This bat may
either fit the wheel or not, depending upon the plan adopted. The dome
is to raise up the bottom of the vase and form a foot. The table may be
covered with a piece of oil cloth or may be kept slightly damp. The
first attempt should be to build a cylinder as this form is easy to
construct and to keep true, so that the attention may be devoted to the
manipulation of the clay.
It is first necessary to roll out the clay into cords which should be a
little thicker than the proposed walls are to be. These cords should be
as uniform as possible and should be rolled quickly to avoid undue
hardening. It is best to roll them as required. The domed bat is made
quite damp and upon it should be marked the diameter of the cylinder to
be built. A roll of clay is taken, one end laid in the center of the bat
and the rest is coiled around it in a spiral line. When the disc so
formed has reached the proper size, the coils are gently rubbed over
with the fingers until they have thoroughly united and the lines of the
spiral have disappeared. The clay disc may now be turned over and the
rubbing continued on the other side. The circle is cut true and a new
coil is laid on the outer edge thus making a shallow circular tray. In
raising the walls it is best to pinch off the roll of clay when one
circle has been completed and the new roll should be begun at another
point so that all the joints will not be at the same place. This plan is
better than coiling a long roll in a spiral for in this case one side of
the piece will be higher than the other.
After three rolls have been laid in position the wall, both inside and
out, should be worked like the bottom so that the rolls will disappear
and the clay be welded uniformly together. This should be done without
water or with as little as possible. The use of water is very tempting.
It makes the clay so smooth and seems to help but it will inevitably
make the work sloppy and will tend to soften the walls.
After three or four rolls have been worked in, the piece should be laid
aside for some hours to stiffen. If this be not done the weight of the
second building will cause the work to sag and fall out of shape. For
this reason it is well to have two or three pieces in hand at once so
that there need be no waiting. When the cylinder is of sufficient height
it should be allowed to become quite stiff and then the irregularities
should be corrected with a little soft clay which is worked into the
joints. The whole surface may now be gone over with tools and brought to
the required finish. As soon as the clay is hard enough it should be
removed from the damp bat and placed upon a dry one to become dry.
In the method of building by pieces no rolls are prepared but the clay
is taken, pinch by pinch, each morsel being pressed into place as the
work goes on. This plan is somewhat more plastic in effect and is well
adapted to free-hand work; the resulting pottery, however, is generally
thicker and heavier.
The craft of building is not mastered until the lines of a drawing can
be successfully followed. The clay is apt to choose its own way and the
result will be very different from what the potter intended. The design
should be carefully worked out on paper, full size if possible, and the
clay form should be compared with the drawing as the building goes on. A
profile may be cut in cardboard and this, applied to the clay from time
to time, will verify the line, but all such mechanical aids should be
used sparingly as the value of this work depends largely upon the sense
of freedom and self-expression which belongs to it.
The thickness of the clay walls is a matter of great importance. A small
piece should not be so thick as to feel clumsy and heavy, nor should a
large piece be so thin as to lose the sense of strength and solidity.
It may be found on drying the ware, that cracks, especially in the
bottom, are developed. The cause of this may be in the clay. A clay
which is too plastic or too fine in the grain will surely crack. Such a
clay may be opened or meagered by the addition of ground flint or fine
grog. The cause may, on the other hand, be in the building. If the
welding of the coils or pieces be imperfectly done, cracks are sure to
result. If the bottom be too thick it will crack. A great strain is put
upon the bottom in drying. The clay must be able to shrink and while the
side walls are able to settle down on themselves, the bottom is pulled
in every direction by the sides. The bottom should be made quite thin in
the center and thicker toward the edges. This will help to avoid cracks.
A bad crack cannot be successfully mended. It is best to break the piece
and begin again. To burn it means the loss of the clay but the clay will
be saved if the damaged work be withheld from the kiln. A small crack on
the edge is also hopeless. A crack showing on the edge of a piece is a
bad fault. A small crack in the bottom may be mended by dampening the
place carefully and pressing in a little stiff clay.