RERAMIC STUDIO 
171 
the pan on the floor or table. The bat will be found to have 
a thin raised edge and this should be removed by scraping, 
not cutting, with a straight-edged knife. Professional mould 
makers use certain rectangular pieces of thin steel called 
scrapers, and any thin piece of steel with a straight edge may 
be made to answer the purpose. It will be very useful for the 
clay worker to have six or eight of these bats. They are the 
most handy things imaginable, and even when there are two 
score lying around one is often at a loss for another. 
A plaster basin or dish for drying clay is almost indispen- 
sable. This is made in the same manner as the bat, except 
that the frying pan cannot be used. A simple method is the 
following. A shallow dish is procured of which the diameter is 
about two inches less than the bat, or else a bat is made about 
two inches larger than the dish. The dish is filled with plaster, 
blended with water as already described, and allowed to stand 
until set. The inside of the dish should have been thoroughly 
greased to prevent adhesion. The solid block of plaster 
formed by the dish is taken and inverted on the bat which 
will show a margin of an inch all round. Both block and bat 
are now thoroughly greased. Instead of grease mould makers 
use a preparation of castile soap boiled almost to a jelly. A 
long strip of stout paper is now prepared and is tied round 
the bat to form an open vessel like a baking tin. The paper 
forms the walls and the bat the bottom while the plaster block 
rises in the center. The paper walls must be at least an inch 
higher than the plaster block. A good length of string should 
be wound around the paper and when quite secure a supply 
of plaster is mixed and poured as before. This must cover 
the basin block to the depth of at least an inch — better if a 
little more. When set, the paper is removed, a thin knife 
blade is inserted between the bat and the new plaster and 
the}' will easily separate, the block being found imbedded in 
its mould. The detaching of this is not so easy but can be 
successfully accomplished with a little care. Bearing in mind 
that the newly made mould must not be damaged a pair of 
holes may be dug in the back of the plaster block. These 
should be cut so that the bar of plaster between them will 
form a handle. Taking hold of this it is usually possible to 
give a twist which will effect a separation. If this be not suc- 
cessful the edge of the mould may be struck with a mallet 
while the block is held firmly, one or both of these efforts will 
always succeed. The worker is now in possession of a plaster 
bowl which will be of the greatest service for many purposes. 
All mixtures in ceramic work are made in water because it is 
practically impossible to pass dry mixtures through fine sieves. 
Wet mixtures can be readily freed from mechanical impuri- 
ties by straining through fine wire or silk bolting cloth. 
Hence a ready means of absorbing superfluous water is de- 
sirable. On a large scale the filter press is used. In the studio 
and laboratory plaster does the work. 
In the previous article we spoke of the preparation of 
crude clay from the garden lot. Such a clay will almost in- 
variably burn to a red terra cotta. To some artists this may 
seem objectionable on account of the color and it will there- 
fore be well to give directions for the preparation of a white 
or cream colored ware and also for staining the same if a 
colored body be desired. 
White pottery is the product of a variety of substances. 
Clays of various sorts supply the plasticity. Ground feldspar 
is the factor which produces density or vitrification and ground 
flint or quartz renders the ware refractory to heat and dimin- 
ishes the contraction under fire. 
Clays are divided into Kaolins and Ball-clays, the former 
used for whiteness, the latter for plasticity ; of the Kaolins the 
most useful are mined in Delaware, North Carolina and Penn- 
sylvania, the Ball clays are found in New Jersey, Kentucky, 
Tennessee and Missouri. From Florida comes a most useful 
clay which is called a plastic Kaolin, but which is, in fact, a 
very pure Ball clay. 
(continued) 
w 
Inside Punch Bowl (See next page) 
