JIGGER AND JOLLEY WORK
"Earth I am, et is most trwe, desdan me not, for so ar you."
--From an old platter.
Dishes, platters, and to some extent bowls, are usually made on a _Jigger
and Jolley_. The jigger has a revolving head, fitted to receive moulds.
The jolley has a pivoted arm to which different profiles may be clamped.
In factories these things are complicated and go by power, but in a studio
where the output of platters and dishes is likely to be limited something
simple will do. Where the wheel is strong, well-hung, and fitted with a
removable head, a contrivance as shown at Fig. 21 can be fitted by any
carpenter, that should serve all purposes.
The vertical supports of the jolley arm should be quite rigid. The arm
itself must so pivot that the face of any profile screwed onto it will
cross the head of the jigger, or wheel if one be used, through the centre.
In other words, the cutting profile must form a diagonal of the circular
head. Then, too, it must be hung at a height sufficient to allow a fairly
thick block of plaster being used for a mould.
[Illustration: FIG. 21--MAKING A DISH.]
When making these moulds, the slotted wheel head or the jigger head is
removed and soaped or oiled. Then a circular block of plaster is cast to
fit. This may be done with the aid of a roll of linoleum, much in the way
described in casting. The paper cone will, of course, be replaced by the
wheel head, bedded face up in clay. This plaster block has to be moulded
to the exact size of the dish or plaque required. To do this a profile of
zinc is necessary. The true section of the dish is drawn full size, and
profiles giving one half of the back and front are traced on a stout sheet
of zinc. The zinc is roughly cut to shape with shears and then finished
with a file to a chisel edge (see cut). The two profiles are then firmly
backed with shaped wooden forms, slotted to screw onto the arm of the
jolley. The profile giving the _face_ of the plaque is securely adjusted
in a horizontal position, the inner point, giving the centre of the
platter, being exactly over the centre of the jigger head. The plaster
block, which should be turned down before it sets hard, is shipped back
into position, the jigger revolved and the profile gradually pressed down
until the true section is obtained, _i.e._ when the profile is exactly
horizontal again. The mould is now removed, trimmed at the sides if
necessary, and set apart to dry. It is then ready to use. The mould is
slipped into position and revolved to insure even rotation. Then the
profile giving the back of the platter screwed onto the arm and both
adjusted until the stop allows the profile to rest at just that distance
from the mould required by the thickness of the platter. (Fig. 22.)
[Illustration: FIG. 22--PROFILE IN POSITION ABOVE PLATE MOULD.]
The arm is then swung clear of the mould, which is well sponged with water
to receive the clay. This is carefully wedged and then rolled out or
batted flat on a piece of leather until it is a little thicker than the
thickest part of the platter (see Fig. 23). The slab so made is smoothed
with a palette knife, taken up, leather and all, slapped onto the mould,
clay side down, and the leather removed. The clay is now well dabbed down
with a wet sponge or dabber, to take out all wrinkles, pressed firmly onto
the mould and the waste cut off.
[Illustration: FIG. 23--CUTTING EDGE OF PROFILE.]
Now the jigger or head is set spinning, the jolley pulled over it, and the
profile gently pressed into the clay. Water is used freely to prevent the
profile sticking, and as it becomes clogged the clay is removed. The
turning is continued until the profile comes to a stop on the rest. Holes
that may appear should be filled up before the finish, at which time the
surface should present a smooth unscratched appearance. The shape is
allowed to dry on the mould until tough enough to be slipped face down
onto a perfectly flat slab dusted with fine sand or flint to prevent
sticking. In this position it is left to dry, when the edges are nicely
trimmed with fine sandpaper.
For bowls the process is similar, but the mould here gives the outside and
the profile the inside as in cut. (Fig. 24.) If made on the outside, they
split before they can be removed. With small bowls the clay is wedged and
a lump pressed into the mould by hand. With large bowls requiring a deep
foot this must be turned separately and stuck on after the bowl is removed
from the mould.
[Illustration: FIG. 24--BOWL.]
Where a jigger and jolley is not available, plates and bowls may be
duplicated as follows: Place the plate bottom up on a well-soaped surface
or a piece of glass. Should the plate not lie quite flat, caulk the
apertures with clay, then all round and distant one and one half inches
from the rim, build clay walls, or fix a containing band of linoleum, of
sufficient height to allow plaster being poured in an inch and a half
above the base or foot of the model. Mix fairly stiff plaster and pour in.
Let it set, and then remove walls and the model. This gives a mould of the
reverse of the plate or bowl. The mould is thoroughly dried before using
and then sponged with clean water. Clay of the desired thickness is then
rolled out as described and applied to the mould and dabbed flat with a
sponge or dabber. The finish is imparted with the fingers and the surplus
at edges trimmed with a knife. When tough, the press is slipped out and
reversed to dry on a piece of sanded glass. Where there is a rim to the
plate or bowl, this should be filled in cleanly with clay before the whole
is pressed. It is of course impossible to mould thus bowls that possess a
deep or under-cut foot.
[Illustration: FIG. 25--PLATE MOULDED TO GIVE BACK.]
[Illustration: FIG. 26--MOULD. TO GIVE FACE OF PLATE.]
[Illustration: THE KICK WHEEL.]
[Illustration: Egypt. B.C. 2000 ANCIENT EGYPTIAN POTTER.]