142 
ttERAMIC STUDIO 
CLAY IN THE STUDIO 
Charles Bums 
EVIDENCES are not far to seek that the persons who were 
once called "amateur decorators" are fast becoming 
artist potters. The law of survival of the fittest must work 
its inexorable way, and those who refuse to bow to the inevi- 
table will be swept away. From a social and humanitarian 
point of view, it is sad that those who have devoted years — 
often their best years — to certain lines of work, suddenly find 
that fashions have changed and they are needed no longer. 
Some there are to whom change means ruin, but there are 
others, and we venture to think the vast majority, to whom 
change is welcome as the best evidence of progress. 
For example, ten years ago, the china decorators who 
attempted to produce conventional design were few indeed, 
while to-day they number the best and most progressive 
mineral painters in their ranks. This change has been a 
source of satisfaction to the critic and a blessing, even if in 
disguise, to the artist. And now a further change is impend- 
ing. When, at the World's Fair, certain foreign jurors criti- 
cised the work of American Mineral Painters on the ground 
that much of the china was European and none was made by 
the decorator, some active brains got to work. There was 
aroused a general feeling of dissatisfaction and the question 
was argued " Why can we not make our own ware?" 
Circumstances have since then been tending towards the 
solution of the problem and it seems that the way is rapidly 
opening towards the consummation. What, then, is to be the 
end? For what goal is the artist potter to aim? 
In answer to these questions it may be said that the 
courses are various and the goals many. There may be a de- 
velopment of underglaze painting but this pre-supposes a ware 
on which to paint. The delights of glazing are open, but 
again, ware to glaze is necessary. 
Let us then attack the problem from the very beginning 
and endeavor to show how the embryo potter, who is already 
an artist in feeling if not in fact, may give expression to the 
thought which lies dormant within. 
The first need is the clay. Nay, that is hardly a fact. 
The first need is the impatient artist soul, aching for action; 
nor is the clay even the second need, for the nature of the 
clay is determined by the kiln, but this part of the problem is 
in a fair way to be solved to the satisfaction of all concerned, 
so that it will be best to assume a kiln capable of a tem- 
perature sufficient to melt cone No. 2 (2175 F.) As reference 
will be made from time to time in these papers to the afore- 
said "cones," it will be well to explain at once what they are 
and why they are used. 
Dr. Seger, the German ceramist, some years ago- under- 
took to construct a series of test pieces which should indicate 
by melting, the temperature in which they stood. By mixing 
together lime, feldspar clay and quartz with certain fusible 
ingredients, he succeeded in graduating his compounds so that 
cones or pyramids made from them would bend over and melt 
in regular succession as the heat was raised. These Seger 
cones are now made in this country by Prof. Edward Orton of 
Columbus, O., and are graduated from number 010 to 01 and 
from i to 1 7. No. 010 is the most fusible of the series and its 
melting point corresponds with that of silver. The lower 
numbers count downwards, so that 03 is softer than 01. The 
higher numbers count upwards, so that 3 is harder than 1. 
Hard pottery needs a temperature of about cone 9 for 
body and cone 6 for glaze, but soft pottery made from natural 
clays can be burned at cone 01 or 1 and glazed at cone 06 to 
03. The cones cost one cent each and will keep indefinitely. 
They cannot, however, be used more than once. 
In use, the cone is set on a morsel of clay so that it will 
not fall over, and is placed in the kiln where it can readily be 
seen. When the heat reaches the required degree, the cone 
softens and bends over, collapsing finally and melting to a 
glass or slag. On a large scale it is customary to use cones of 
several numbers at one time, the softer to give warning and 
the harder to show the completion of the burn. A kiln, then, 
which will melt cone No. 2 is desirable. Now let not the 
artist who has not such a thing throw down this paper in dis- 
gust, exclaiming that the impossible is demanded. A friendly 
pottery, even a brick yard, may be made use of. The heat 
of a brick kiln is somewhere about the heat necessary and 
some pieces of pottery enclosed in a sagger may be safely 
burned therein. 
In consequence of the editor's request to avoid techni- 
calities, explanation must here be given of what a "sagger" is. 
Pottery kilns are of two main classes, open and closed. 
The latter are called "muffle" kilns. They are of the type 
generally used by mineral painters and the essential part of 
their construction is that the flame does not enter the kiln 
itself but circulates around the walls. In an open kiln the 
flames pass through the firing chamber, and hence the ware 
must be protected. This protection is accomplished by en- 
closing the pottery in saggers or cases made of fire clay. 
These saggers, when full, are piled one over the other in the 
kiln, the bottom of each forming a close cover for the one 
below. These saggers can be purchased cheaply from most 
potteries and can be used repeatedly until broken. 
By this time readers will be saying "cut the cackle and 
come to the 'osses" and it seems as if the way were clear for 
the day at last. 
Clay as a means of artistic expression is valued on account 
of its plasticity, but clay which is highly plastic is unsuitable 
for pottery on account of the extreme difficulty of drying 
without damage. In studio modeling, it is an advantage for 
the clay to remain moist, and glycerine is often added to ac- 
complish this but the potter wishes his clay to dry rapidly 
and without warping, for then it will burn safely. This 
property is termed the porosity of clay, not the porosity of 
the burned ware. The two have no necessary connection but 
the porosity of the clay mass. The extent of this porosity is 
a matter of experiment. It can be increased by the addition 
of fine sand to the clay. Some clays are found having the 
right amount of plasticity and porosity; some have too much 
of one or the other. In most parts of the country good clay 
can be found. Just below the surface soil of the garden lot 
there will be, likely, either clay or gravel. The latter will 
yield no satisfaction but the former may be made to serve. 
In dry weather a good supply should be dug and stored in 
loft or barn for use. Clay is more easily worked when quite 
dry than when damp and tough. Spread out on the floor it 
is crushed and sifted to remove stones, and then the dry 
powder is sprinkled into a large vessel full of water. By thus 
adding the clay to the water rather than the water to the clay, 
a perfect soakage of each particle of clay is secured. The 
mixture of water and clay, called slip, is now well stirred, 
sticks and leaves floated off, and allowed to settle for three or 
four minutes, the liquid being carefully poured into a second 
vessel ; wooden buckets will answer well. A second supply of 
water is added to the sediment, again stirred and poured off. 
At the bottom of the first vessel will now be found all heavy 
