Archive for March, 2006

Spinning

We have already mentioned spinning in terms of a textured pattern on green ware (see page 47). This technique can also be applied in underglaze decoration with exciting results. The procedure is basically the same, the only difference being the use of color. Rather than textured spirals, underglaze spinning produces spirals of color. Naturally, underglaze spinning, too, can be applied only to round or cylindrical pieces.

The “one stroke” underglazes are more satisfactory for spinning purposes than the opaque underglazes, since they do not “drag” as much and will blend to a greater degree. Even with the “one stroke” colors, however, it is a good idea to add a little glycerin to the color so that it will “slide” better during the spinning process.

A single color may be used or, for more interest, several colors may be applied in succession. Keep the sponge well saturated with color or you may find that you are pulling off color rather than putting it on. Experiment with various colors until you find combinations that are pleasing. You can achieve interesting effects by spinning a light color (turquoise, for example) over the entire piece and then spinning a contrasting color (perhaps brown) along the outer edge or in the center. A color-spun piece can be extremely handsome and often needs no other decoration.

Sponging

Sponging provides the decorator with one of the most attractive underglaze backgrounds. A sponged background, while simple enough to produce, lacks the too regular appearance often present in a sprayed or spattered background. Because the over-all effect depends upon the type of sponge, the way in which the sponge is handled and the amount of color applied, sponging lends a great deal of individuality to the ceramic piece.

For general purposes, the fine-textured “elephant’s ear” sponge (available at most art and ceramic stores) produces the most satisfactory sponging, although unusual effects are possible with artificial and coarse-textured sponges. Dampen the sponge and dip it into diluted color. If the sponging appears too light, you can always go over it again, but if it is blotchy and heavy at the start there is nothing to do except wipe it off and begin again. To prevent spotty sponging you must handle the sponge correctly. Apply the color to the surface of your piece in gentle, patting motions, avoiding jerky, erratic movements. Don’t press hard with the sponge or a splotchy pattern will usually result. The main difficulty in sponging is avoiding a spotty, uneven pattern; a sponged background should be soft without any distracting heavy blotches of color.

Practice on paper first until you become familiar with the technique. Sponging is not difficult, but, like anything else, requires some practice to perfect. Once you have mastered it, do not limit sponging to all-over backgrounds; later in this chapter we will discuss other ways of applying sponging to your decorating.

Spraying through cloth

Some of the most interesting underglaze backgrounds can be obtained by spraying color through fabrics of various textures. Dishcloths, burlap, netting, crocheted doilies and cheesecloth are among the textured cloths that can be used for background effects. The cloth should be thoroughly dampened so that it adheres to the surface of your piece or the force of air from the airbrush will move the cloth, distorting the pattern.

To insure an even application on all sides, it is a good idea to place the ceramic piece on a decorating wheel that can be turned during the spraying process. A variety of effects is possible by rearranging the folds of the material. Cloth that is wrinkled, folded or pleated will produce an entirely different pattern than cloth that has been placed flat on the surface.

Spatter

An easy yet effective background is a spatter background that can be achieved very simply with a toothbrush. Apply a liberal amount of underglaze color to the toothbrush and draw your forefinger through the bristles, producing spatters of color. Stand the piece upright, if possible, and hold the toothbrush at a right angle to it; this prevents unwanted globs of paint from dripping off the toothbrush onto the piece.

The spatter may be of one color or, for a more interesting effect, it may consist of several colors. The color may be spattered over the entire surface, or used only as an edging, or a heavy concentration of spatters may be used just in the center of the piece. Often a solid color background can be softened and given interest by heavy spattering of a contrasting color around the edge of the piece. Use this technique freely either by itself or as an accent on other underglaze backgrounds; you will find it a solution to many of your decorating problems.

No matter what type of design you plan for a ceramic piece, unless you give the background the same amount of consideration the decoration cannot be wholly successful. In planning a decoration, both the design and the background should be worked out together since the effectiveness of one depends upon the other. Any elaborate or complex design will certainly become lost if applied over an equally complex background and a severely simple design applied to a flat, uninteresting background will result in a rather stark decoration. The problem of selecting a proper background is actually no more than a problem of balance and contrast: a soft background for a severe design, a patterned background for a simple line design, etc. Decorating with underglazes provides you with an endless choice of backgrounds with which to experiment. Learn as many background techniques as possible and apply them with imagination and intelligence, always remembering that whatever background you choose must complement the design. You will find underglaze decorating an exciting challenge! (See Appendix.)

Solid background

A solid background may be applied by spraying or brushing. When brushing on a solid coat of color, the main problem is one of even coverage. Nothing is more discouraging than to discover that the fired piece is full of uneven patches of color. One of the reasons for poor coverage is the wrong brush; too many decorators attempt to cover a large area with a small, round brush. The best brush for backgrounds is the square sable, either the ” or 1″ size. However, even with the right brush, the manner in which the color is applied remains a determining factor in the matter of even coverage.

The surest way to obtain an even background is first to dilute the color slightly with water and brush on the color with the brush strokes moving in one direction; then do the same with a second coat but change the direction of the brush strokes; finally, apply a third coat (full strength this time), alternating the brush strokes. One of the dangers in applying a solid background lies in too heavy an application of color because of eagerness to insure an even coverage. By diluting the first two coats and alternating the brush strokes you can usually eliminate this danger.

While you can, with practice, perfect the brushing-on technique, the most satisfactory way of obtaining a solid background is by means of an airbrush. If you plan to do even a limited amount of production work, an airbrush is an invaluable tool, not only for solid backgrounds but for many other effects impossible to achieve any other way.

Although there is nothing complicated in the handling of an airbrush, some practice is required to handle it efficiently and easily. Dilute the underglaze color to a very thin consistency for spraying or it may clog the airbrush. Beginners have a great tendency to get too close to the piece, thereby saturating it with color. Another mistake is to “spot” spray, that is, to move the airbrush in jerky motions, heavily spraying a small area at a time, rather than moving the airbrush in a continuous circular motion that will cover the entire area progressively with light coats.

One disadvantage to spraying is that you must take great care in the further handling of the piece since the color will dust off easily, leaving finger marks and smudges on the sprayed surface. This can usually be remedied, however, by adding syrup or honey to the underglaze color before spraying.

Defects

Improper application of underglazes will cause various defects in the finished piece. One of the most common of these is chipping, which may be caused by too thick an application of color or improper cleaning of the piece. Another difficulty is the “bleeding” of a color during glaze firing. Blue and black underglazes seem to be the worst offenders. Usually too heavy an application of color is the reason for this bleeding or running. The glaze, which becomes fluid during the melting process, can cause a heavily applied underglaze to flow. By bisque firing the un-derglaze decoration before glazing, bleeding can usually be eliminated since the underglaze will become fixed and less liable to be attacked by the melting glaze. Sometimes too heavy an application of the glaze itself may cause bleeding, although again this is less likely to occur if the decoration has been bisque fired.

Brushes

The choice of brushes is very important to the ceramic decorator. A good decoration can never be made with poor materials and it is a wise decorator who invests at the start in a few good brushes. Sable brushes, although more expensive than poorer grade brushes, are cheaper in the long run since they will long outlast a cheap brush and give your decorating talents a better chance in the process.

Illustration 66
Left to right: ” flat sable brush for backgrounds and large areas; #8 sable for large design areas; #3 sable for small areas and general detail; # 1 liner for fine detail.

The size of the brush depends a good deal on the decorator, but, in general, try to avoid the very tiny brush. If you invest in a good brush that holds its shape, it is not necessary that it be a minute size even for fine lines. You should not need anything smaller than a #1 or #2 liner for very fine detail work. A #3 or #4 is a good brush for general detail work and filling in small areas. For large areas or backgrounds, a flat ” or 1″ sable is essential. You will have to experiment with various sizes until you find the most comfortable brush, but whatever its size, make sure the brush is a good one. Remember, though, even the best brush cannot give the best service unless it is treated with respect. Always clean your brushes in water immediately after use, smooth them to a point between your fingers and let them dry in an upright position. Never leave a brush, bristles down, in water or paint, not if you expect to use that particular brush again!