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POTTERY DECORATION
UNDER THE GLAZE.
BY
M. LOUISE McLAUGHLIN.
CINCINNATI:
ROBERT CLARKE & CO.
1880.
COPYRIGHT.
M. LOUISE McLAUGHLIN.
1880.
CONTENTS.
PREFACE. v
INTRODUCTION. vii
CHAPTER I. xiii
CHAPTER II. 28
CHAPTER III. 36
CHAPTER IV. 41
CHAPTER V. 68
CHAPTER VI. 79
CHAPTER VII. 85
PREFACE.
It has been with some hesitation that I have undertaken to write a
manual on the decoration of pottery under the glaze. This feeling was
caused by the fear that I should not be able to treat the subject in
as comprehensive, as well as comprehensible, a manner as it deserved.
Nevertheless, in an experience of more than two years, chiefly spent
in experimenting on different methods of under-glaze decoration, I
have learned some things which may be of use to others, and have
thought that a treatise upon the subject from an unprofessional,
yet practical standpoint, might have its place in the literature of
ceramics which has now become so extensive.
Let it be understood, however, that in the following pages there has
been no attempt to deal with the occult mysteries of the potter’s
art, but simply to give an account of results attained and facts
acquired, every one of which can be vouched for as a record of actual
experience.
I would like here to express my sense of indebtedness to the potters
who have, by their courtesy and attention, contributed to these
results, and particularly to Mr. Joseph Bailey, Sr., of the pottery
of Mr. Frederick Dallas, whose intelligent co-operation and valuable
advice have been of the greatest service.
_Walnut Hills.
Cincinnati, May, 1880._
INTRODUCTION.
The decoration of pottery under the glaze offers opportunity for the
production of work, beautiful and artistic in a high degree, and in
its simpler forms gives to those who do not aspire to the higher art,
a most fascinating and labor-rewarding study. I can not, however,
assure those who wish to enter the domain of decorative art by this
interesting road, that they will find the way strewn with roses.
On the contrary, discouragements are likely to occur so frequently
that it is only by the exercise of a considerable amount of patience
and perseverance that any advance can be made. But such are the
attractions of the work that its enthusiastic votaries will not be
deterred from its prosecution by any difficulties in the way, and
if immediate and perfect success can not be assured, an exceedingly
interesting occupation will be revealed to the learner, and to the
earnest worker can be promised the reward of faithful labor.
I would like here to insist, however, upon the necessity of a
thorough and serious study of drawing as a preparation for this as
well as for all decorative work, and to enter a most emphatic protest
against the theory which seems to prevail in some quarters, that
any one can paint upon pottery acceptably. With little preparation
other than the possession of some colors, brushes, clays, and pieces
of pottery, the devotee of art enters upon the work of decorating
(?) pottery. Alas! disfiguring it, for it is a lamentable fact that
of the pottery now being painted by amateurs (some of the work
by professional decorators might also be included) a very large
proportion has its value diminished rather than enhanced by the work
put upon it.
This would not be so frequently the case if the scope of the work
were limited to the capacity of the worker. We see every day,
attempts, in which the failure to reach the point aimed at is
absurdly obvious, where, if the effort had been less ambitious in its
aim, the result would not only be less an object of ridicule, but of
far more intrinsic value.
In other departments of human handiwork, some natural capacity,
as well as a certain amount of training, is considered necessary
to successful practice, but, in art, such is the ignorance of the
general public, any one is thought eligible to the profession of an
artist, and much passes under the name of art, which has no claim to
that honorable title.
I do not wish to discourage those who are willing to enter into this
pursuit as humble, patient learners, but to warn those, who are eager
to obtain at once the rewards only given to years of faithful study,
of the futility of their desires. It is perhaps idle, however, to
warn or to advise them. The consciousness of their folly will only
come to them after experience, and knowledge gained from failure,
shall have given them some comprehension of the difficulties which
their ignorance prevented them from seeing.
In art, as in all other pursuits, there is no royal road to
excellence, and those who do not think it necessary to learn the
rudiments before attempting the higher branches, will learn to their
cost, if they are capable of learning any thing, that nothing was
gained by leaving out these stepping stones in their progress.
The time is never misspent which is devoted to honest, well-directed
efforts in acquiring the art of drawing. The excuse so often offered,
that the practice of the art is only intended as an amusement, and
that therefore it is unnecessary to undergo the drudgery of learning
it thoroughly, is one which is unworthy. To those who offer it I
would say, pray amuse yourselves with something else rather than an
art, into which, to obtain even an insight, demands the best that any
one can give.
These remarks apply as well to the decoration of pottery as to any
other department of art work. Although from its peculiar nature and
various uses this material yields itself to many and varied styles of
decoration, yet this decoration, however simple, must be planned and
executed according to sound principles, to be of any artistic value.
The best preparation for the work of decorating pottery, therefore,
is a thorough knowledge of drawing and an understanding of the laws
which govern all decorative art.
Sources of information upon these subjects, drawn from competent
instruction, books and periodicals, are daily becoming more numerous
and accessible, and one who desires to practice the kind of
decorative art we are now considering, should cultivate his taste
and augment his skill by these means, and especially by close study
of nature in all its various forms. It is only in this way that the
student will be enabled to accomplish work which will be a source of
pleasure and profit to himself and others.
POTTERY DECORATION UNDER THE GLAZE.
CHAPTER I.
POTTERY.
We will consider in this chapter some facts in regard to pottery,
which, although of a very elementary character, are not so generally
understood as may be desirable. These facts relate to the substances
of which pottery is composed, the processes of its manufacture, and
the methods by which it is or can be decorated.
Two chemical substances, viz., silica and alumina form the basis of
all pottery clays. These substances are themselves infusible (except
under the compound blow-pipe), but by admixture with other materials
more susceptible to the action of heat, they are made useful to the
potter’s art, and, when subjected to a high temperature, fuse and
form the hard, insoluable combination with which we are all familiar.
Porcelain, and the finer kinds of earthen-ware, are made from clays
artificially combined of various natural elements, in such a manner
as to produce the qualities desired, while the coarser wares are
generally made from clays in a natural or unmixed state. These clays
agree in their essential characteristics, but contain other elements
which cause certain differences of color, susceptibility to heat,
plasticity, etc. The differences, therefore, which exist between the
many kinds of pottery manufactured, may be said to be due, not so
much to a diversity of the materials used, as to the changes produced
by the combination of the same materials in varying proportions.
It is unnecessary that we should here enter into the details of the
mixture of different pottery clays, for which each manufactory has
its own formula. A few words, indicating, in a general way, the
causes of certain easily-recognizable qualities, will suffice.
The peculiar beauty and translucency of fine porcelain, is due
to an excess of silica, or the vitreous element of pottery, in
its composition. This is attained by the use of kaolin, a fine,
white clay, produced through the agency of natural causes in the
decomposition of feldspar, which is itself a silicate of alumina, and
one of the principal ingredients of granitic rocks. In porcelain, it
may be said, that the proportion of silica to alumina is about three
to one, and the other ingredients, such as iron, potash, chalk, and
soda, exist only in such quantities as are necessary to cause the
fusion of the two first-mentioned elements. It is fired but slightly
the first time. This leaves the body of the ware very soft and
porous, and upon the application of the glaze the latter is absorbed
into the body, and by its action upon the materials composing it,
produces a translucent effect.
We refer, here, to French porcelain. In the manufacture of English
china, the process is radically different. The last-mentioned ware
is sometime spoken of as “bone china.” This term has reference to
the use of bones from which the lime required in its manufacture is
obtained. This element produces a translucent quality in the body of
the ware independently of the action of the glaze, which in this case
forms merely a coating upon the surface of the previously hard baked
body.
Earthenware possesses less of the vitreous element, and the first
firing is continued until the ware becomes so dense that it will not
absorb the glaze, and the body remains opaque.
The term pottery, is more strictly applicable to the kind of ware
last mentioned. It is to this that especial reference will be made
in the following pages, in describing methods of manufacture and
decoration.
Earthenware is of various colors, ranging from pure white, through
the cream white and cream-colored wares to decided yellow, and lastly
red. The clays can also be artificially colored, and changes in color
are also produced by different degrees of temperature in firing.
Ordinarily the process of firing produces a material change in the
color of clay. Thus, a grey-tinted clay will assume a bright, yellow
color, and a dull brown, green, or blue will be changed to a bright
brick-red, under the action of the fire.
The heat used in firing should produce partial vitrification. If a
piece of ware has not been fired sufficiently to produce that effect,
it is said to be “soft-baked.”
White earthenware requires the greatest degree of heat in firing. In
regard to the wares made from clays retaining the colors produced by
the elements which they contain, in a natural state, it may be said
that the amount of heat necessary for proper firing, decreases with
the depth of color. This rule, although it may accurately indicate
the temperature at which any given clay should be fired, is simply
artificial, except in so far as the depth of color shows the presence
of an amount of foreign matter, which by its action increases the
fusibility of the clay.
Red clay, being very susceptible to heat, is commonly used as a test
in the firing of white ware. The same clay will change in the process
from light red to dark brown, and so enable the experienced fireman
to determine the degree of heat existing in the kiln.
Clays should be prepared for the making of pottery by careful
sifting, dissolving in water, and, as a final precaution, straining
through sieves made of fine, silk lawn. In this way all foreign
particles are removed, and the clay, having attained the consistency
of dough, is ready to be molded into the shapes desired. This is done
in molds made of plaster of paris, or it is “thrown” by the hands of
the potter on a turning-wheel, or, again, by a combination of these
processes.
Before firing, the ware is said to be in the “green state,” in which
condition it passes from “wet” to “hard green,” and finally to
“white,” when it is ready to be fired. If fired before it has become
sufficiently dry, it will be liable to crack, or scale, from the
sudden expansion of the moisture confined in the clay. When dry, it
is placed in “seggars,” or boxes, made of fire-clay, which are piled
upon each other in a kiln, constructed for the purpose of firing the
ware.
During the process of drying and firing, the clay loses a certain
portion of its bulk. The amount of this shrinkage varies in different
clays, but ordinarily may be said to be about one-eighth. A piece
of ware, therefore, made from clay which exhibits this degree of
shrinkage, would be one-eighth smaller after firing than before.
The shrinkage is also modified by the degree of heat to which the
clay has been subjected in firing, and there will sometimes be a
perceptible difference in the size of two pieces of ware, made from
the same clay, and of equal size before firing, after having been
fired at different temperatures.
The length of time consumed in firing, varies with the qualities of
the different wares. In the manufacture of white earthenware, the
firing lasts from thirty to forty hours, while the more common kinds
of ware require less time. In kilns of ordinary size, a thousand
dozen pieces of ware are frequently fired at once. Of course,
considerable time is required to place the seggars containing the
ware in the kiln. Some hours must elapse before the kiln and its
contents will become cool enough to permit its being opened with
safety, so that the firing of hard-baked pottery may require two or
three days for its completion.
The first firing completed, the ware is said to be in the “biscuit,”
and is then ready to be glazed. This matter of glazing is a very
important one, and the success of the whole very largely depends
upon the manner in which the operation is performed. To insure
a successful result there must be the nicest adaptation of the
materials composing the glaze to the body of the ware. The glaze for
each kind of ware must be suited to its especial characteristics, and
it can therefore be imagined that the number of glazes in use is very
large. Each pottery has its own glaze and the variety is infinite.
The glaze used upon the finer kinds of earthenware consists of
materials similar to those of which the body of the ware is made,
with the addition of boracic acid (a powerful flux), which with a
little lead renders the glaze fusible. In the lower grades of ware a
larger amount of lead is used for a flux, and this causes the glaze
to fuse at the comparatively low temperature at which these wares
are fired. A glaze made of materials that fuse at an unusually low
temperature is called a “soft” glaze. Some glazes are so soft that,
when fired, they can be easily scratched by the point of a steel
instrument. The glaze of good and durable wares is, however, so hard,
that the point of the sharpest knife will make no impression on its
surface.
The materials of which the glaze is made, are combined in the proper
proportions and diluted to form a liquid of about the consistency and
the appearance of cream. The piece of ware is then dipped carefully
into the liquid, and so skillfully manipulated that it is completely
covered with a coating of the glaze of the necessary thickness.
After having been covered with the glaze, which, before firing, has
the appearance of an opaque white paint, the ware is ready for the
second firing. This is done in what is called the “gloss” kiln, in
which the heat is not brought to such a high degree as in the biscuit
kiln, but is sufficient to fuse the glaze, and cause it to form a
glassy, transparent surface, which should completely cover the body
of the ware, and present an equally brilliant appearance in every
part.
If the glaze is not suited to the body of the ware, and does not
shrink equally with it, its surface will soon present a network of
fine cracks. A glaze in this condition is said to be “crazed.” This,
among potters, is considered a serious fault, and in ware intended
for cooking or table use, is certainly very undesirable.
Old Japanese crackle-ware, in which this condition is a
distinguishing feature, is, however, much esteemed, and many, indeed,
the majority of the Japanese earthernwares, both ancient and modern,
display a surface of fine-crackled glaze, which may not be said to
detract from their value as articles of ornament.
A similar effect is also seen in old pieces of glazed ware which have
seen long service as cooking utensils, in which case it has been the
natural result of the usage to which they have been subjected.
In some modern wares, both French and English, decorated under
the glaze, this defect is seen. In these cases it has been caused
by the use of a softer glaze than the body of the ware demanded.
This expedient has been resorted to in order that the brilliancy
and beauty of the colors might be preserved. These articles being
intended only for ornament, beauty is more of an object than
durability, and this defect of glaze may be permissible as the means
of obtaining more brilliant effects. In certain methods of decoration
this may be a necessity, but these cases are exceptional and
experience leads me to believe that it is possible to obtain beauty
of coloring with a glaze which will remain intact. It is to be
hoped, however, that with the improvements in making colors the time
may come when it will be possible to obtain colors which will retain
their beauty under the degree of heat necessary to the production of
an article which a practical potter would call a perfect piece of
ware.
Pottery can be decorated either _under_ the glaze, _with the glaze_,
as in the case of majolica, in which the color is effected by the
use of colored glazes and in the decoration of soft porcelain
(_pâte-tendre_), where the painting is executed upon the unbaked
glaze, and, lastly, _over_ the glaze. We will concern ourselves only
with the first of these methods. A few words, however, may not be
out of place here, upon the differences between over and under glaze
painting, which are frequently compared and as frequently mistaken
for each other.
_Over_-glaze painting, as is well known, is executed upon the glazed
surface of the finished ware with vitrifiable colors having enough
flux or fusible material in their composition to cause them to
fuse at a comparatively low temperature, and so become attached
to the glaze. _Under_-glaze decoration is effected by the use of
colors which contain less flux, and consequently require a higher
temperature for their fusion. It can be executed either upon the
ware in the “green” state, or, as is more commonly the case, in the
biscuit. These two methods of painting differ materially in their
effects. Any one familiar with these effects can readily discover
whether a piece of pottery has been decorated over or under the
glaze. Those who are not practically conversant with the two methods
can be easily misled, and mistakes are frequently made by those who
should know better, as to the method employed in the case of a piece
of ware in question.
A certain delicacy of tint and firmness of outline characterizes
overglaze painting, which is easily recognized by experts, but those
who can not distinguish between the two methods by this means may
ascertain to which class the decoration belongs by looking aslant
the surface. The glaze upon the painted portions of a piece of ware
decorated over the glaze, will not, even after the most perfect
firing, equal the glaze upon the uncovered portions in brilliancy,
and there will probably be certain inequalities of surface between
the painted and unpainted parts which will be revealed to the touch.
If the decoration has been executed under the glaze the surface will
be uniformly covered with a brilliant glaze. Of the two, underglaze
painting is probably the most difficult, as the colors are more
liable to change under the action of the great heat to which the ware
must be subjected, and the final results being, therefore, somewhat
uncertain, can not be accurately counted upon, until experience has
been gained from repeated failures. On the other hand, overglaze
painting, while not subject to the changes produced by the fire, to
so great an extent, is more difficult as regards the manipulation
of the painting upon the glazed surface. The facilities for the
practice of overglaze painting are greater than those afforded for
painting under the glaze, which last, requires not only the handling
of an artist who has acquired facile use of the brush and some
experience of pottery clays and colors, but also the assistance of an
intelligent and skillful potter.
Let us not, however, laud one method of painting at the expense of
the other. Both are good in their way, and confined within their
proper limits, have beauties peculiarly their own. Overglaze painting
possesses a delicacy of effect and a variety of color which the
underglaze decoration can not rival. The latter is, however, the most
artistic as well as the most effective, and lends itself more readily
to the uses of decorative art and to the modern taste in color.
It is this latter method of decorating pottery which we will now
consider in some of its various forms.