Read Ebook: Pottery decoration under the glaze by McLaughlin M Louise Mary Louise

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It is necessary to exercise this care in keeping the ware moist, in order to prevent the clay, which is applied to the surface in painting, from cracking during the process of drying. It must always be borne in mind that the material made use of in painting is simply clay, which has been artificially colored, and, as clay, becomes subject to the rules which govern all work of this kind, whether it is making pottery, modeling, or painting faience.

The drying of the clay used in painting can, however, be retarded by the use of gum tragacanth, which may be mixed with it. It would, perhaps, be better always to take the precaution to use this medium, although when, as remarked before, the body of the ware is still quite soft, and the condition of the atmosphere such as to prevent too rapid drying, the painting may be executed simply with the use of water.

Just here a caution as to the use of gum tragacanth may be given, and that is, that it is better not to mix the gum with more of the colored clay prepared for painting than is to be used at once. When mixed only with water, the clay after becoming dry, can be easily rubbed down again with water; but if gum tragacanth has been used in the mixture, and it has been allowed to dry upon the palette, the gum will not re-dissolve readily under the action of water and the palette knife, and the mixture will be full of small particles of undissolved gum, which will render it unpleasant to work with. To prepare gum tragacanth for use, it is dissolved in water, to which may be added a drop of salicylic acid to keep it from turning sour.

The clay, which is to form a body for the colors, must be dissolved in water until of a proper consistency for painting. It should be a little thicker than the diluted clay used by potters and technically called "slip." As to the quality of the clay, the desideratum is that it shall be colorless and not inclined to crack in drying. The clay used in the manufacture of white granite ware is probably the best clay for this purpose, generally accessible. This can be mixed with all the colors without injury to the tint of any. Parian clay produces the most beautiful effects, and, where it is possible to procure it, forms the best medium for this painting. More care must, however, be exercised in its use, as it is very liable to crack in drying, and from the translucency produced in the body by the action of the fire, must be laid on more thickly than clays which have greater opacity, to produce the effect desired.

In the case of yellow, which does not always stand the fire well, it is best to mix the color with a yellow-tinted clay to ensure a successful result. C. C. clay, which is a cream-tinted white, will effect this. If a darker yellow is desired, clay which in firing acquires a decided yellow-tint may be used.

A light cream-tinted clay, such as C. C., or "stilt" clay, may be used with yellows therefore, with advantage, with browns and blues without disagreeable effects; but in the case of scarlet, pink, or crimson and greens, nothing but white clay must be used, if purity of tint is desired. The reason for this is that the presence of iron in the yellow-tinted clays injures the colors mentioned.

The clay can be procured from the pottery in broken pieces, or, better, in a semi-pulverized state from the trimming in making the wares. When in this state it is easy at any time to dissolve enough for use. It is, perhaps, better to prepare it just before it is to be used, as the longer clay stands, after it has been mixed with water, the more compact it becomes. When it has just been dissolved, it still retains air among its particles, and this renders the mixture more porous and less liable to crack. It soon dissolves in water and can be stirred until smooth. It may be strained through a sponge, alternately allowing the sponge to absorb the diluted clay and then squeezing it. Probably the most convenient way is to rub the clay in a mortar until all the lumps are dissolved. If a very small quantity only is needed it may be rubbed down upon the palette with the palette knife as it is wanted.

A palette or a slab of glass may be used for mixing the colors and clay. The latter is the best, as it can be procured of large size, and as in this kind of work a considerable quantity of paint is necessary, there should be ample room to mix the colors. A slab of French plate glass, at least twenty by twenty-four inches, may be procured. This can be imbedded in plaster of paris, which will make it stronger, as well as furnish a white surface upon which the colors will show to better advantage.

The colors, after being thoroughly ground, can be mixed with clay in such proportions as may be desired. The white clay takes the place of white, and is used to lighten every tint, as well as to form a body for the colors. It is a good plan, where experience has rendered it possible to do it with judgment and certainty of result, to mix the various tints in water with clay, in quantities, and then allow them to dry. When dry, they can be pulverized and the colored powder can be put away in bottles for future use. This saves time when painting, and also ensures a like result from the use of a mixture which has already been tested and found to be satisfactory. It is only, however, after considerable experience in mixing colors, and verifying their results, that this can be safely done.

As in other kinds of underglaze painting, it may be given as a general rule, that the colors are intensified in firing, in this, however, much more than in other methods. All the stronger colors are intensified to a degree difficult to realize before experience has taught the artist what to expect. They all become several shades darker, and, in the case of blues, blacks and greens, it is more difficult to obtain delicacy, than depth of tint.

In the use of scarlet, crimson and yellow, a considerable amount of the color in proportion to the clay must be used for the darker portions to give sufficient depth. Only enough clay must be taken to give body to the paint, and the mixture should then be applied very thickly. The painter must also bear in mind the fact that the stronger color will overpower the weaker in mixtures, even when the latter is in such degree as to give the color to the mixture before firing. After firing, the stronger color will appear in excess. In making such mixtures, therefore, the stronger color should be used very sparingly, if it is desired that the other should predominate in the tint when fired. Otherwise, the colors may be found after firing to be entirely different from what was intended.

METHOD OF PAINTING.

Let us suppose that the artist wishes to paint a vase. A certain tint being selected for the ground, the color, or colors, which are to produce it are mixed in their relative proportions, according to the hints given above. A sufficient quantity should be prepared to paint the whole ground, especially if a mixed tint, which it would be difficult to reproduce in its exact proportions. It will require some little experience to enable the artist to judge how much will be needed, and, perhaps, it will be somewhat difficult for any one accustomed to painting in other methods, to realize the quantity of paint used in this. It is better to have too much mixed than too little, as it can be kept and used another time.

Before commencing to lay on the ground, it is well to wash the surface of the vase with a thin solution of glaze , or with borax water. This is to ensure the adhesion of the clay, of which the painting is to consist, to the clay of which the vase is made. Previous to this, the vase, if not already in good condition, should be washed over with a brush, or with a sponge dipped in water, or sprinkled until it has absorbed water enough to keep the clay, which is to be applied to its surface, from drying too quickly.

The second coat finished, a lighter tint should be mixed, with which the ground is varied by touches here and there, making the highest light of the ground, while touches of the first tint mixed, give the darker shades. There should be difference enough in tone between the middle tints of the ground, and these lighter and darker tints, to produce a good effect of light and shade, and these touches should be laid on with a free hand, and then softened into the ground, care being taken that the lights and shadows should not end too abruptly.

In these touches, as in all the painting, there must be a certain thickness in reality, as well as in appearance, to make the work effective when finished. The clay shrinks and seems to be dissipated in the process of firing, and if applied too thinly, in any part, will reveal the body of the ware, or some under-tint, perhaps spoiling the appearance of the whole. The transparent effect, produced by a thin layer of clay, which, after firing, shows the under-tint through, is sometimes very beautiful in certain parts of a design. It is, however, difficult to judge by the eye of the requisite degree of thickness necessary to produce this effect, and the heat of the firing may be so great as to cause that portion of the painting to disappear entirely. It can not, then, be safely counted upon, and the best way is to depend solely upon the lights and shades of the painting for the effects desired.

The ground finished, the decorative design may be painted upon it. This should not be outlined upon the surface, but should simply be painted with a free hand, and without too much attention to detail, a brilliant effect of light, shade, and color being the object aimed at in this style of painting.

We will suppose that a floral design is to be painted upon the vase. The middle tint of the flowers can first be laid, the shadows are then put in, and lastly the high lights, laid on heavily, almost giving the effect of relief. Leaves and other accessories of the design may be treated in the same manner. The edge of the design must be softened into the background, to avoid a hard effect after the work is glazed. The process of glazing has a tendency to soften and melt the tints into each other, but this effect must be enhanced by judicious use of the middle tints and shadows of the painting, and by leaving the edges thin. One of the greatest beauties of this kind of painting, when well done, is the effect of the rich colors melting into each other, with a charming indistinctness, which leaves something to the imagination of the beholder.

Those who have not been accustomed to the use of color in such masses, will, perhaps, be embarrassed at first by the difficulty of painting with clay. This will soon be overcome by practice, but, as has been said before, it should always be remembered that it is clay which is used, and, therefore, the work is subject to the conditions which govern the use of that material.

It is unnecessary to enter further into details, as it is only intended here, to give some instruction as to the method of painting, leaving the manner of it to the artist, it being taken for granted that any one desiring to practice this kind of painting should have already attained some proficiency in the use of colors, and should have acquired a knowledge of the rules which govern art.

To such there will simply be the difficulty of learning to work with a new material. If this knowledge does not exist, it will be no easier to succeed in accomplishing any thing, worth the doing, in this, than in other kinds of art work.

With regard to the colors to be used, it is enough to say that a sufficient number can be obtained to produce by admixture, in various degrees, tints for the production of any subject required. It is only necessary to remember, as said before, that in these mixtures the stronger colors must not be in such proportion as to overpower the weaker. A list of useful colors has been given in a previous chapter. In regard to the mixtures of these colors a few words may be of use.

Black is a very useful color for shadows, making, in its admixture with white clay, numerous pleasing tints of grey, which may be varied by the addition of any other color which may be desired. As black is one of the strongest colors, however, it must be very sparingly used where a light tint is needed. In the mixture of blue and green, the former must exist in a much smaller proportion than the latter, if the mixture is to have a greenish tint. Experience alone can give success, but enough has been said to prevent the beginner from making very disastrous mistakes.

The painting must, of course, be executed while the clay is wet, and should be finished in one sitting. If this is not possible, it may be kept wet in the way described for keeping the ware before painting.

In describing the method of painting a vase, we have taken for our model, one decorated with flowers. Decorations can, however, be as varied in regard to subjects as paintings on canvas. Floral decorations seem to be the best adapted to vases, or other objects having rounded surfaces. Plaques and vases, such as pilgrim jars, which afford flat surfaces, may also be decorated with landscapes or figures. For these subjects somewhat different treatment may be adopted, but enough has been said to indicate the requirements of the material, and each artist will find a manner suited to himself.

Decorations of a similar character can be produced upon ware of different colors, leaving the color of the clay for a ground. This has a very good effect when done upon cream-tinted clay in suitable colors. As this kind of ware should be fired at a higher temperature than the deeper tinted and coarser clays, the colors are liable to fade in the firing. This is not undesirable, however, as the faded tints harmonize with the light ground much better than darker colors. Some beautiful effects can be produced by decoration of this kind, which can be supplemented by carving and gilding.

The same method can be used on a ground of dark red clay by the selection of colors which will harmonize with the ground. Yellow flowers look well upon a ground of this character, and the yellow color can be produced, as we have said before, by the use of yellow clay, either alone or as an adjunct to the color.

Monochrome decorations can also be produced, by the use of natural clays of various colors, in the same manner as that pursued in the use of the artificially tinted clay of which we have been treating. Good effects can be produced in this way, with the advantage that the colors will be fully retained in the firing. Red, or brown and white, in various degrees of combination, can be used to produce a design with every effect of light and shade. Also, red, with cream-tinted clay, or the three colors--red, yellow and white--can be used together. These designs can be produced upon grounds of cream, red, or yellow clay.

DRYING.

When the painting has been completed, it should dry very slowly, and it would be better, if possible, to effect this by placing it in a moist, cool place. It is, however, difficult to handle a piece of ware when wet. The clay is in a very soft state, and a sudden jar might cause the vase to fall to pieces.

If the vase has not been in proper condition for painting, or has dried too quickly, it will, after some hours have elapsed, begin to show fine cracks upon the surface of the painting. These may be stopped, before they have gone too far, by passing a modeling tool over them, or, if the crack has become too deep for this treatment, it may be filled with clay as nearly as possible in the state at which the body of the ware has arrived. If the cracks are allowed to go too far it will be difficult to stop them, as they may have extended into the body of the ware.

If the piece is permitted to go to the firing with any cracks, however small upon its surface, they will become widened in the firing, and, especially after the glazing, will show very distinctly.

In the biscuit, they may be stopped by filling them with powdered clay mixed with gum water. But an ounce of prevention is worth a pound of cure, and the safest method is to prevent their appearance in the first place. If this can not be done, they must be stopped as soon as they appear. The finer clays seem to have a greater tendency to crack in drying, and when the cracks have appeared, they are more difficult to stop than in other clays.

FIRING.

When the piece decorated is thoroughly dry, it should be fired at a temperature sufficient to make the body durable, and at the same time to perfectly fix the colors of the painting, so that there may be no danger that the glaze will cause them to run in the final firing. This latter defect may also result from an excess of glaze, and where it exists only in a very slight degree, produces a melting softness which is very pleasing. This effect is, however, so likely to be exaggerated to the ruin of the work that it is best not to run any risk of the kind in firing, and to depend upon the painting alone for the harmonious blending of the tints.

The temperature at which the work is to be fired, must, of course, depend upon the qualities of the clay of which the piece of ware is made. As has been said before, this clay should be one that does not require an excessive degree of heat in firing. The exact degree can be estimated by the potter who understands the requirements of the clay which has been used in the manufacture of the particular piece of ware in question. It may be said that the temperature at which Rockingham ware is fired is suitable for this work, and that a glaze such as that used upon that kind of ware can be used with good results. It is possible to have a glaze so adapted to the body of the ware as to prevent it from crazing, and yet preserve the brilliancy of the colors.

MODELING IN RELIEF.

Under this head may be comprised the decorative modeling of figures and other designs upon pottery, in various degrees of relief. First, we have figures in relief forming decorations upon vases. These, as well as other designs in high relief, belong properly to the domain of sculpture, and the methods of producing them do not vary essentially from those in use in that art. The final process in this case is the firing, instead of the casting in plaster and cutting in marble.

Of the methods of producing floral designs in relief, a few suggestions may be of use. These, as well as the painting described in the previous chapter, must be executed when the body of clay, to which they are applied, is very wet, and the applied clay must in this case be, as nearly as possible, in the same condition. If the clay is not in the proper condition, the work will crack in drying.

The vase which is to be decorated being in the right state, a lump of clay, having the plasticity necessary for modeling, is procured. This may be of C. C., a deeper cream color, or red, according to the color desired. White granite is not plastic enough, and is, besides, liable to crack in drying. But of all white clays, parian forms the most beautiful substance for this kind of modeling. Leaves and petals of flowers can be shaped from pieces of clay, which have been flattened to the required thickness, either by pressing upon a slab of plaster of paris, by means of a weight, such as potters use; or, if the work is not on a large scale, the clay can be shaped in the palm of the hand. The forms can then be cut with a sharp modeling tool. If there is more moisture in these pieces of clay than in that which forms the body of the vase, they should be allowed to remain a short time upon a dry plaster slab. The plaster will quickly absorb the moisture in the clay. When ready, the pieces can be placed in position on the vase, the places where they are to be applied having been previously washed with clay and water , or with glaze water, to make them adhere. Stems are made by rolling pieces of clay between the palms of the hands, or upon a flat surface of wet plaster or wood. They are afterwards allowed to dry, and when in proper condition, applied in the same manner as the flowers and leaves. Delicate touches may be put in with a brush dipped in clay, of a proper consistency for painting. The forms of the design can be shaped and finished after they have been applied to the vase by the use of modeling tools, and, finally, with a camel's-hair brush. The design may also be brushed over with a sponge, moistened with water, which will also be found very useful in restoring the smooth surface of the ground, if it has been injured in the process of modeling.

After the modeling has been completed, the work should be gone over with a modeling tool, and in places where a mass of clay has been attached to the surface, the edges should be under-cut. This will prevent cracking. If this precaution is not taken, a crack thus produced may extend into the body of the vase and render it unfit for firing. Where a large mass of clay occurs in the modeled design, it is better to hollow out the projection from the inside of the vase, to prevent the cracking or warping of the whole in firing, caused by the unequal thickness.

Cracks, which may appear in drying, should be filled, or, if possible, be pressed out with a modeling tool, before the piece is fired. If the crack is so deep that it is necessary to fill it, the place should be cut open with a modeling tool, moistened with water, and filled with clay, as nearly as possible in the same condition as that upon the vase.

Flowers can be modeled in parian clay upon a creamy-tinted ground with good effect. Various colors of deeper tinted natural clays, or clay which has been artificially colored in the body, can be used as the ground of such decorations. Light grounds are sometimes colored after the first firing, in the biscuit; or a ground can be painted in the method described in the previous chapter, while the vase is soft, and the modeled decoration can then be applied instead of the painting.

Decorations of this character in high relief are frequently colored in natural tints, either under the glaze, in the biscuit; or over the glaze. The taste of this manner of finishing relief-work is somewhat questionable, and the same objection might apply to it as to colored sculpture. That it has received the sanction of the best factories in the world is no proof of its being in accord with correct taste, as the many atrocities of Dresden and Capo di Monte testify. Some of the later Haviland faience, however, having a ground in the usual style of that ware with decoration in high relief, colored with subdued tints, harmonizing with the grounds, is so artistically done that one can hardly think it open to this objection, although it can not be considered an improvement upon the earlier work of this establishment in which the colored decorations were simply painted upon the surface.

It is only to the use of colors which imitate those of nature upon modeled decorations that there could be any objection. Relief-work may be conventional in its form, or colored conventionally, in one color or many, or gilded, with perfect taste. The latter method produces a fine effect, but, to make it successful, the color of the ground should be well chosen, and the design simple in form and not too much detached from the surface. The gilding looks best when left unburnished, and should only be rubbed enough to give the effect of dead gold.

Next, we have applied designs in low relief. These are made in several different ways, according to the effects desired. Work of this kind is more commonly executed by the method used in the production of Wedgwood-ware. The designs to be applied are first modeled in clay. Casts are then taken of the models in plaster of paris. Clay of the kind desired for the relief designs is then pressed in the mold and the edges trimmed off. The design can be removed from the mold by the aid of a flat, steel instrument, with a short, broad blade; or a palette knife, which when pressed upon the clay adheres to it and detaches it from the mold. It can then be transferred to the piece of ware to be decorated, to which it is made to adhere by the use of "slip," as described before.

This method is very useful, indeed, indispensable in the manufacture of such wares commercially, when the same designs are to be repeated many times, but it is hardly to be recommended for artistic work, except for conventional designs, borders, etc. This method of casting the forms in a mold may be useful, however, in the reproduction of leaves of intricate outline, which can be made of various sizes, and, from the plasticity of the clay, can be infinitely varied in position according to the taste of the worker.

When objects of delicate and intricate form, such as threads, spider's webs, nets, and sometimes leaves, are to be represented in work of this character, it can be accomplished by dipping threads, or nets of cotton, or, if leaves, the natural leaves themselves, into "slip." The clay adheres to the threads, or forms, and after it has set sufficiently, they can be placed upon the object to be decorated. On firing, the substance inclosed within the clay is dissipated and the clay only, remains. Some very wonderful and beautiful effects may be produced in this way; but, as these delicate forms are necessarily very fragile, especially if much detached from the surface, they are only suitable for articles intended solely for ornament.

Designs in low relief can also be applied with the brush in the forms desired, which may afterward be shaped and finished by the use of modeling tools, or, when dry, carved with steel instruments. This latter is said to be the method by which M. Solon executes his exquisite designs in fine white clay upon ware which has been colored in the body. One of the greatest beauties of M. Solon's work is the transparent effect produced where the clay has been left so thin as to show the colored ground through.

The colored grounds in the Wedgwood and Solon ware are produced by the use of a fine clay body, which has been artificially colored throughout, which, in the case of Wedgwood, is finished by a very slight glaze, and in the Solon ware, by a full glaze, by which the transparent effects of certain parts of the work are brought out. The colors used in the body of these wares are blues, dark greens, and olives, and also black. Where it is not possible for the amateur, for whom these hints are written, to obtain such wares for decoration, very pretty work can be produced, as has been mentioned before, by the use of a body of naturally colored clay upon which white or a light-colored clay can be applied.

Relief-work can be finished with a full glaze, a very slight glaze, or can be left unglazed. As a general thing it may be said that the modeling in a design in high relief will look best with but a slight glaze, or none at all. The slight glaze is called by potters a "smear" glaze, and is effected by firing the work in a "seggar," which is glazed upon the inside. The unglazed ware absorbs enough glaze from the glazed surface to give it a semi-glazed appearance, which is very pleasing. Work in partial relief, as well as articles in full relief, can also be finished by the application of colored glazes. This is the method by which the ware known at the present time as majolica is produced. Blue and green glazes of this kind are frequently to be obtained in potteries in this country, where they may be applied to work which has been modeled. Other colors in majolica glazes are to be had from the dealers, and if the colors desired can not be applied at the pottery, the artist can apply them with a brush in the same manner as paint is used upon the biscuit. The effect of work of this kind can also be enhanced by gilding put on over the glaze.

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