Part 14

Most beginners in clay modelling will expect, perhaps in the early stages of their work, to be made acquainted with the potter's wheel; for who has not heard of this interesting device? It is of interest chiefly because of its practical utility in the manufacture of pottery; and yet no one can forget the potter's song with which Longfellow begins his beautiful poem Keramos, making it a text for a sermon on the philosophy of life:

"Turn, turn, my wheel! Turn round and round Without a pause, without a sound; So spins the flying world away! This clay, well mixed with marl and sand, Follows the motion of my hand; For some must follow, and some command, Though all are made of clay!"

_Potter's Wheel Unnecessary._--The potter's wheel was used in comparatively early times and has been intimately associated with the art ever since. But it requires much physical strength and considerable skill to use it effectively; and its use has been by no means universal. We find the Indians of our own time and people of other races, expert in building pottery by hand, using the method of coiling. It seems best, therefore, to advise beginners to adopt the simpler method and to forego the use of the potter's wheel. The comparative inexpensiveness of the hand method of building is another point in its favour. The tools required are few and simple. Inexpensive and easy methods are favourable to the experimental stage; and it is well for the amateur to have every encouragement to experiment freely both with methods for building and with designs for his ware, keeping in mind always that the beautiful is generally the simple and strong, not the fantastic and complicated.

_The Method of Coiling._--It will be understood, therefore, that in general the process to be followed consists in building up the bowl or jar or whatever the design may be by using coils of clay of the right consistency, welding and shaping them together, and scraping them down, if necessary, until they are ready to receive the first firing. After this they may receive a coating of glaze and be fired again. At first the beginner will find his chief interest simply in experimenting with the building up process.

MATERIALS AND TOOLS

The materials and tools needed are as follows: Clay; oil-cloth, 18 inches square; cotton cloth or flannelette, 18 inches square; a few simple modelling tools; a soft pencil; drawing paper; card-board, 6 ply; a plaster of paris "bat," or a piece of slate.

_Clays._--It will be necessary to add a word of explanation in order that these materials and tools may be well selected. There is a great variety in clays, ranging from a very coarse red clay used for flower pots to the finest white clay used for porcelain. The latter is called kaolin and is very pure. A good modelling clay may be obtained from dealers in school supplies or from potteries. In some localities, especially in the neighbourhood of brick-yards or other clay industries, a satisfactory clay may be easily found. But, however obtained, some experimenting will be necessary to test its suitability. The modelling clay is probably the least liable to yield disappointing results.

The cotton cloth or flannelette is to be moistened and used to wrap up the clay in order to keep it from drying too rapidly during the intervals when it is set aside. This will not be necessary during the early part of the process, for then it is desirable for the clay to stiffen as rapidly as possible by natural means.

Of the modelling tools needed some can be whittled from hard wood. They are not expensive, however, and the beginner will perhaps find it well to obtain most of them from a dealer in artists' materials. The accompanying illustration shows some of these, among them a very useful tool (F) with brass wire loops which are in turn wound with finer wire. F and C are especially useful for scraping clay too soft to be easily managed with smooth edges. The thumb-like tool A is perhaps the most generally useful of those shown here.

In this connection it is well to emphasize the fact that _the greatest of all tools is the human thumb_. Cultivate its use. Most modelling and building can be managed with the thumb, assisted by the fingers.

_The Bat and How Made._--A plaster of paris bat will be found exceedingly useful. A sheet of thin, unsized paper serves well, however, for a surface on which to build; but the dry plaster of the bat absorbs the moisture of the clay at the bottom and hastens the stiffening process. This bat can be easily made. Take a small quantity of water (a half pint or more according to the size of the bat required), sift into this from the hand an equal amount of plaster of paris, and stir it in until a little dry plaster appears at the surface. After a little more vigorous stirring let it rest a few minutes and then pour it into tin pans which are 4 or 5 inches in diameter by 1 inch deep. The pans should be previously coated on the inside with a thick soap solution, made by dissolving soap in hot water to the consistency of a thick cream. The bats will harden in 10 or 15 minutes and may be easily removed from the pan, ready for use.

PROBLEM: A BOWL FOR FLOWERS

This problem naturally divides itself into six important steps, as follows: The design or profile; building and shaping; decoration, if any; firing (bisque); glazing; and firing the glaze.

_The Design or Profile._--As in all problems of decoration the first step is found in design. For present purposes we may consider a bowl as having a diameter as great as or greater than the height. The bowl will be more interesting from the standpoint of variety if there is a difference between its height and its greatest diameter, and also between its diameters at the top and at the bottom. The accompanying drawing shows such differences.

Another example of the value of variety is to be found in the curve of the profile. A line that is simple but constantly changing in its degree of curvature--as, for example, an elliptical curve--is more pleasing than an arc of a circle, which is sometimes called the curve of limitation. It should be noted that a curved form, in order to be forceful, should have some dominant curve in combination with others which are subordinate. The profiles illustrated in the following drawings have this dominant element and are in no case composed of arcs of circles. These varied, interesting, yet simple lines--live lines as they are sometimes called--consisting in each case of only two or three elements, are given here merely as suggestive material. A little experimenting will show unsuspected possibilities in strong, forceful curves, and the young student is advised to make many experiments in the effort to discover such possibilities. An example of profiles to be avoided is given in Problem II, on page 309. That these are vase forms and not bowl contours is immaterial. _A_ is commonplace because the two parts of the curve are too much alike. _B_ is unrestful in its three curves of nearly equal size. If the suggestive profiles illustrated in the foregoing drawing be turned upside down it will be noted that very few of them seem as pleasing as before. It will be found also that a different ratio of height to diameter will give very different effects with the same profile. A bowl having top and bottom alike may, so far as design is concerned, be classed with the pill box. We don't know which is the top until we have spilled the pills. If attractive pieces of pottery are found with the top and bottom of equal diameter and with curves in themselves objectionable, it will invariably be found that the attractiveness consists in some beauty of glaze, colour, or decoration which is prominent enough to conceal the defects of form.

_Natural Forms._--It may be well to add a word here in regard to the imitation of natural forms in designing the general shape of any piece of pottery; and that word is a very brief one. Avoid them. Nature is a great teacher in all branches of art; but in pottery her suggestions are to be used as decorative elements rather than for fundamental shapes. A fish with a flower in its mouth does not seem appropriate; but a bowl for water-lilies, while it may not take the form of a fish, might reasonably have a fish as an element of its decoration.

_Testing Profiles._--A good way to study the effect of the profile of both sides of the bowl is to fold the paper on which the profile is drawn vertically through the centre and transfer the line reversed by rubbing the back of the paper, thus giving the other half of the drawing in exact symmetry. When the general shape of the profile has been tested in this way one side should be redrawn carefully; then, with the paper folded along the centre line, so that the pencil line falls outside, the whole form may be cut out; and then it may be unfolded. The next step is to begin to build up the design in clay.

_The Building._--Roll out a coil of clay a little thicker than the bottom of the bowl is to be; perhaps 3/8 or 1/2 of an inch will serve, since the bottom is to be hollowed slightly by scraping. The roll should be uniform in diameter and rolled as little as possible, in order that it may not become too dry. Upon the piece of paper or the plaster bat start to coil the roll from the centre until the desired size is reached, then smear the rolls together, working toward the centre. Turn the coil over and work the other side together, truing up the circle and making the bottom of uniform thickness. Avoid the use of water in smoothing the coils together. It may seem to make the work easier, but it softens the clay and invites careless work.

With another coil begin to build up the sides, making a complete circle, and, having pinched off the ends where they meet, join them carefully. Lay two or three coils in this fashion, pressing each coil firmly into place as it is laid, and smooth them together as in the base. The process is illustrated in the drawing. If the clay is very soft, the work may be set aside to harden a little, while a beginning is made upon other pieces. It is well to have two or three pieces in the process of construction at the same time.

_Testing the Work._--A template or gauge will be needed to test the work as it progresses from the first rough stages to the finish. This is made of card-board by cutting out an exact copy of the profile, leaving at the bottom sufficient width to insure rigidity when the template is held upright on the table or bat.

As the work goes on, if the design requires that the form should be "brought in" toward the top, the coil must be laid a little inside of the profile desired, as the smoothing tends to increase the diameter slightly. In all the building, allowance should be made for this enlargement. When the coil is high enough and of the shape desired, it should be allowed to stiffen until it is rigid enough to handle. With the various modelling tools the surface should then be scraped wherever it is necessary to remove the hardened clay in order to give a symmetrical shape to the desired profile.

A drawing is shown to illustrate the process of scraping. The surface should be left smooth and even; and this may be accomplished without water or sponge. The flat sides of the scraping tool may be used to polish the clay as soon as it becomes leather hard--_i. e._, hard and stiff, but before it begins to whiten and dry.

The lip or top of the bowl will require special attention. It will probably need to be thinned down and have all sharp edges removed. Then the bowl should be turned upside down and the bottom hollowed out to a depth of 1/16 to 1/8 of an inch, leaving a "foot" or rim around the outside of the circle to give it steadiness.

_The Decoration._--After the bowl is complete as to its general form, the problem of its decoration, if there is to be any, must be solved. This may be studied during the intervals when it is necessary to set the bowl aside to harden. If the form and colour are good, the bowl may possess a charm that will not be improved by decoration. On the whole, less decoration, rather than more, should be the aim. The three vases illustrated at the top of a following page are examples of pottery without decoration. (See page 308.)

Generally speaking, bowls like the one we are building may be decorated by one of three methods: By sinking lines or channels in its surface by means of a sharpened, chisel-like stick (D, page 285); by modelling or carving the surface; or by painting the surface with coloured "slip" or with coloured glaze. It should be explained that "slip" is a mixture of clay and water of the consistency of cream; it may be coloured or uncoloured. A combination of two or more of these methods is, of course, possible. Examples of the first two methods are shown in the illustrations of bowls, vases, and tiles. A combination of the first and third methods was used in decorating the tiles of the middle row shown in Plate XIV opposite page 316.

_Classes of Decoration._--The _form_ of the decoration is simply a matter of space division, as illustrated by two examples shown below. It is evident, too, that decoration, so far as form is concerned, divides itself naturally into three general classes: (a) The horizontal band; (b) the vertical division; (c) a combination of these two. The last will prove to be the most common of the three. It should be noted that an all-over pattern, which has been left out of consideration as tending to monotony, would commonly be a combination of both horizontal and vertical methods of division. It should be noted also that the presence of other than vertical and horizontal lines in pottery decoration does not affect the main classification. Typical examples of these divisions are illustrated in both bowls and vases, as well as in the cuts A and B. It will be seen in each case that one scheme or the other predominates and that there are possibilities for great variation in treatment.

Analyzing the patterns shown in all these illustrations, we find that the band or horizontal scheme offers a succession of large and small spaces, giving variety and rhythm. In many of those patterns showing the combination type there is a concentration or "knotting" of the line at regular intervals, frequently at the intersection of both horizontal and vertical elements. This is well illustrated by the left-hand bowl of the middle row shown in this plate opposite page 294. When the method of painted decoration is employed the concentration point is composed of mass instead of line. All this serves to give emphasis and rhythm.

For subject matter in decoration natural forms may be used as shown in the vase at the left of the top row illustrated in Plate XIII, opposite page 312. Or an abstract arrangement of lines may be employed, as shown in its nearest neighbour, which may or may not have had its origin in a very much conventionalized natural motif. The essential thing to remember is that the divisions of spaces must be varied and rhythmic and the decoration suited to the method of application.

_How the Design is Applied to the Clay._--After the design has been studied as much as possible on paper it should be planned out on the bowl with a soft pencil, allowing sufficient space for the incised line or channel to be made. The clay should be leather-hard--_i. e._, stiff but not dry. The spacing around the circumference should be made exact, deviating somewhat, if necessary, from the spacing of the paper drawing. A good way to manage this important step in the process is to measure the circumference at the point of greatest width with a narrow strip of paper and then to divide this circumference by folding the paper evenly into the number of units desired. By wrapping the paper around the bowl again the points of division may be transferred to the clay and then projected upward or downward vertically to the belt that it is desired to meet. It is necessary to make sure that the vertical lines are true "meridians" and do not swerve to the right or the left. In order to test the horizontal lines, measurements may be made from top or bottom. All of this work is best done free-hand; for, aside from the value of the eye training derived, hand-built pottery is seldom exact enough to permit of a more mechanical method of planning its decoration.

The drawing on the clay having been completed, the next point is to choose the tool best fitted for the work and carefully make the cuts, deepening them from time to time as the work progresses. If the design is to be worked out in line, a chisel, like that illustrated in D (page 285), may be whittled from a pine stick. It is held nearly upright and used as a scraper to cut out at first a shallow channel. Reserve should be exercised in cutting, because, generally speaking, there is danger of making the design too insistent. Some of the best designs are very subtle and quiet. Care should be taken, however, to allow for a slight filling in of the hollow by the glaze when it is applied.

_Modelling a Decoration._--If the decoration is to be modelled it would seem wise to do it, in whole or in part, as the work is built up; but in this case great care will be needed to keep a firm hold on the relief and unity of the decoration. It will be easy to over-model the work.

_How Under-glaze is Applied._--For decoration with under glaze the colours given under the head of glazing (page 304) are mixed in different proportions with dry powdered clay and water to form a colour paste. This is painted on the "green" or moist clay, forming a smooth and even surface. Experience will teach the proportions of colour to be mixed with the clay. These proportions vary greatly with different colours. A very strong colour like cobalt will give a deep blue if mixed in the ratio of one part by weight of cobalt to ten parts of clay. Colours like the oxides of iron and copper are of medium strength, and antimony is quite weak.

Before the work is left to dry it would be well to make sure that all corners and rough edges are smoothed off as they will show light and rough through the glaze. The use of sand-paper, however, is not advised, though it may occasionally be used in the emergency of an accidental roughness remaining after the piece is dry. The aim should be to have all clay work show something of the plastic nature of the material out of which it is made.

_Firing._--Pottery must be "bone" dry before it is fired. A very satisfactory portable kiln for firing may be purchased for from $34 to $175, according to the size. The smallest size, which is illustrated in the next drawing, will be ample for the needs of one or two persons. If, however, the amateur does not care to go to the expense of purchasing a kiln, it is generally possible to find a pottery factory in the vicinity that will undertake the firing and perhaps the glazing.

_Temperature Required._--Pottery is fired at a temperature varying, according to the clay and the glaze used, from approximately 1800 to 2000 degrees Fahrenheit. Modelling clay fires at 1958 degrees Fahrenheit, or what is called "cone 04." This term comes from the fact that the heat is gauged by pyrometric cones, which can be seen through a spy hole attached to the kiln. These cones are graded compositions of various materials and possess different degrees of resistance to heat. They are usually set up in clay in groups of three or more. When one of them melts it bends over, as illustrated in the accompanying drawing, which shows cone 05--the most fusible one--completely "down," and 04 at a point indicating that it is time to shut off the heat from the kiln. This must be done gradually and the kiln must be allowed to cool completely before it is opened. This is especially necessary when firing the glazes described in the following section, which require the same temperature as modelling clay. Further details about firing and caring for the kiln may, of course, be learned from descriptions accompanying the apparatus. Pottery comes out of the first firing in the kiln a dull porous ware and in colour either cream, buff, or red, according to the amount of iron in the clay. In this state it is called "bisque" or "biscuit."

_Glazing._--It is necessary to bring the pottery up to the condition of bisque before it can be glazed; or, to speak more accurately, before it can be over-glazed; for it has already been shown how the so-called under-glaze is put on before the first firing. The subject is somewhat technical, and it will not be possible in a single chapter to take up the details extensively. Briefly speaking, the glazes most used for this class of work are the lead glazes--combinations of "white lead" or carbonate of lead as a flux with kaolin, flint, whiting, feldspar, and other ingredients. These are supplied in powdered form and are ground together in water by means of a mill or a large mortar and pestle; a mortar 8 inches in diameter will serve.

_Grinding the Glaze._--The grinding should continue about an hour. It should be said, however, that there is such a thing as grinding too fine. After the glaze has been properly ground a small quantity of gum tragacanth, dissolved in water, is to be added as a binder to prevent flaking and rubbing off in handling. It is also a good plan, though not always necessary, to strain the glaze, as soon as it is ground, through fine muslin. The tools and materials needed for this work may be itemized as follows: Lead carbonate, whiting, Canadian feldspar, Florida kaolin, French flint, white oxide of zinc, and various other oxides and colours noted in the text; earthenware bowls, 10 or 12 inches in diameter, for holding the glaze; large spoons, preferably aluminum; agate mortar and pestle, 8 inches in diameter.

_Example of Matt Glaze and Bright Glaze Mixes._--Two mixes are given below calculated to fuse at cone 04. One has a "matt" or dull velvety surface, and the other has a "bright" or shiny surface. The matt will be found more desirable for general work because it harmonizes better with flowers and foliage. The figures given below refer to units of weight. Metric weights (grams) are most convenient to use, but any units will serve so long as the same one is used throughout. The matt glaze should be of the consistency of thick cream, the bright glaze somewhat thinner.

MATT BASE Lead carbonate 154 Whiting 25 Canadian feldspar 83 Florida kaolin 51

BRIGHT BASE Lead carbonate 142 Whiting 20 Canadian feldspar 84 Florida kaolin 8 White oxide of zinc 8 French flint 44

The bases itemized above are colourless and there must be added to them from 3 to 6 per cent. of colouring material that will stand heat. A list of materials with their colours when fired is given on page 304, together with a few typical combinations of colours in quantity suitable to be added to the glaze bases given above. The following lists are by no means complete, and it is expected that the young decorator will make use of these colour mixtures simply as an introduction to quite extensive experimenting:

COLOUR MATERIALS