Archive for January, 2006

Sgraffito is one of the most effective and popular techniques used in ceramics and is especially favored when an intricate line design is desired. It is essentially a cutting or scratching technique. The clay piece is first coated with an engobe and while the engobe is still damp a design is scratched with a sharp tool, revealing the body underneath the engobe. You may use almost any type of scratching tool from a wire loop to a pen point, but the tool you will probably find most occasion to use is a scratch knife point that can be inserted in a pen holder. Most art stores and ceramic dealers carry scratch knife points in assorted sizes. Try different size points to lend more interest to your design, since a design consisting of lines of unvarying width is often monotonous.

If you find the cutting difficult, the engobe may be too dry. Keep a damp sponge handy and go over the surface whenever the cutting seems difficult or the engobe begins to chip around the incised line. If the piece is extremely dry, cover it with a damp cloth for about fifteen minutes before you sgraffito.

When you are incising a design remember to pull the tool toward you. Never try to cut a line with the tool moving away from you or from bottom to top. Even if you have to turn the piece around from time to time, make certain that you keep the tool moving toward you. Otherwise, in addition to producing a very awkward line, you will find that the engobe tends to chip around the cut line. The quality of your line is all-important in a sgraffito decoration. There is something very stark about a line; it stands alone with no blending of colors to disguise its beauty or ugliness. A line is like the little girl who “when she was good she was very, very good, but when she was bad she was horrid” and the only way to achieve a “very, very good” line is, as with anything else, by constant practice.

There are various ways of applying an engobe for sgraffito purposes. It may be sprayed, painted or dipped. Dipping a piece only partially in an engobe provides an interesting background for sgraffito work and is

Illustration 60
A sgraffito design was here applied to a background of sponged engobes. The scratched-on design reveals the body underneath the engobe.

particularly effective on tall pieces that often require a breaking up of solid color. Your sgraffito design will then be the same color as the undipped portion of the piece. A large area of engobe can also be painted in the form of a simple pattern (leaf, fish, bird, etc.) with sgraffito work inside the area. Interesting variations can be obtained by sponging different colored engobes on the piece as a background for a sgraffito design. (See Appendix.)

Other interesting decorations are possible by dragging a comb or fork through a wet engobe. For this technique, the piece should be wet when the engobe is applied. Paint a strip of engobe on the wet surface, applying it heavily. While the engobe is still wet, draw a comb or fork through the strip, dragging

Illustration 56
For slip trailing, the vase is turned upside down and engobe, squeezed in generous globs along the edge, trails down in stripes.

Illustration 57
Practice is needed to make a vase like this.

Illustration 58
For “dragging” engobes, lines of engobe, with honey added to keep it moist, are trailed on a plate.

Illustration 59
A fork is then dragged across the wet engobe lines. For this technique to be successful, the engobe should be applied heavily.

it across the surface of the piece. An interesting repeat design can be formed by dragging the comb through several strips of different colored engobes.

Slip trailing

A more elaborate type of decoration can be made by slip trailing, a method by which the engobe flows from a slip tracer, a syringe-like device that trails a design onto the piece. You can buy a slip tracer from your ceramic dealer. You may also use a plastic squeeze bottle – the kind mustard comes in.

The line produced by slip trailing will be thick, raised and somewhat erratic, due to the continuous flow of slip from the tube which allows little time for indecision. Once you set the slip tracer down on the surface of the piece, the slip flows even when your hand is not moving. You will probably require some practice with this technique to acquire sufficient control of the tool, but when you have mastered it you will find slip trailing a very expressive method of decorating.

A “fun” variation of this technique is wet slip trailing. The entire surface to be decorated is first covered with an engobe which is painted on with a large brush, sprayed, or dipped on the piece. While the engobe is still wet, the design is trailed on with a contrasting colored slip. The excitement inherent in this technique stems from the fact that hardly any control is possible, for as the two engobes mix and settle together, a certain amount of distortion results-anything can happen!

The lines of the design may zig where they should have zagged, sometimes producing bizarre effects and, if you feel adventurous, you can shake or tap the piece to exaggerate the distortion. This technique is, of course, not very dependable, but it certainly results in effects impossible to obtain any other way! (See Appendix.)

The most direct method of decorating clay with color is by using a slip of contrasting color on the piece. Slip used for this purpose is referred to as “engobe” and may be painted, trailed, stenciled, sprayed, sponged, dipped or inlaid. Each technique has its own special quality and each requires a different design treatment and handling of the material. Engobe decoration is usually done on leather hard or, sometimes, wet clay; rarely are engobes used on bisque ware. The effectiveness of this decoration is due largely to the fact that the decorating is executed in clay. You thus avoid a “painted on” look and gain a certain amount of richness and unity.

How to make engobes

You can purchase prepared engobes in a variety of colors, ready to use, but you may want to mix your own. Although you can use metal oxides or body stains as colorants, the easiest way to make an engobe is to add liquid underglaze color to your white slip. The slip will lighten your color a great deal so you must use approximately 25% underglaze color in order to obtain a color of any depth.

Engobe painting

Any piece that is to be painted with engobe should be thoroughly sponged first as a damp surface is more receptive to slip. If you add glycerin to the slip, you will find it easier to brush on. (Wherever glycerin is mentioned in this book, mineral oil may be substituted.) Slip does not flow as freely as paint and is apt to “drag,” making brush strokes difficult; therefore, any decoration made by engobe painting should be limited to a free, simple type of design with the slip applied heavily. This technique does not lend itself to intricate decoration or delicate brush strokes.

Illustration 55
The red clay vase is enhanced by a design painted on with white engobe.