In dyeing, the difference between cloths made of animal and of vegetable fibers is important, as animal fibers resist acids better, and plant fibers resist alkalis. It is important to state which kind of cloth is to be used when buying dyes; some textile dyes are suitable for both.
Many cloth dyes take effect only in hot or even boiling water. These are, of course, unsuitable for batik work, as wax melts at well under boiling point. Cold dyeing produces, on the whole, much better colors on animal than on plant fibers. Animal fibers also hold the dye faster than vegetable ones with the primitive methods we are discussing. Wool is mostly too rough for batik; a smooth silk is the best choice, for the colors come out with greatest purity on silk, and its sheen and texture, especially if it has a linen weave, are added attractions. A great deal of work goes into a multicolored batik, which justifies the use of a good natural silk, even if other cloths are suitable.
Although today there is an inexhaustible selection of textile dyes with every imaginable nuance of color, the number of dyes that work out well under the primitive conditions of domestic dyeing is limited. Anyone intending to go in for batik should make a pattern book. It is important not to make the patterns too small, for colors look quite different on a large piece and on a small cutting. Different kinds of silk will need testing, so that the right weave is chosen for the right design.
Taffeta weave is usually the most suitable; a delicate design should have the smoothest taffeta. This is woven from thread unwound from an undisturbed cocoon, unlike slub silk, which is taken from shed cocoons and cuttings, and thus consists of short fibers which have to be properly spun before they can be used. Siub silk is thus more fibrous and, like linen, has irregular thick knobs which are very attractive in the cloth, but which in batik make sharp line drawing impossible. Tussore silks look the same; they are wild silks taken from wild silkworms and are more difficult to dye. Silks are often dressed with metal salts to make them stiffer, and these, too, take dyes badly.
As we have said, batik is a process of resist dyeing. Only one color can be applied at a time, and when there are several colors everything which is to remain in the first color has to be treated with "resist" in the subsequent dips, while those exposed to the next must be protected afterwards from later colors. The more colors in the design the longer and more complicated the process. Some colors can, of course, overlap, so that every place where a later color is to come need not necessarily be covered every time, but some experience is needed to envisage the combinations of colors ahead.
It is wise to make several test pieces of a given dye, say yellow, to test not only the pure color but also how it mixes with blue, red, and whatever other colors are to be used. Let us give a practical example: first we dye in yellow and cover everything which is later to be blue. For the second dip we cover everything that is to stay yellow, and dye blue; this will give blue where the wax was applied at the yellow dip, and green everywhere else. Thus two colors are given by one dip. If before or after the yellow there were a red dip, the blue could give not two, but three colors according to the waxing: blue, green, and purple.
It is not enough to know the theory of color combinations, every coloring substance reacts differently and must be tested in its combinations with cloth and other colors.
All this shows how important it is to prepare the work beforehand and not to make a first attempt with more than two or three dips. Even that can give five or six different colors. It should be borne in mind that overprinting always produces a darker tone than direct printing.
In the example we discussed using blue and yellow, the blue will always be lighter in tone than the green. If the green is wanted as light or lighter than the blue it will have to be dipped in a separate green dye.
The graphic effect of batik is due equally to the manipulation of the tjanting and the fact that no gradual transitions of color are possible. As in sgraffito and mosaic each patch of color lies by the next without any modulation. To this is added a texture that cannot be either influenced or eliminated deliberately; it can at best be made closer or sparser. When the cloth is pressed into the dye the hardened wax breaks up and the dye, of course, penetrates into the cracks, making a fine veining of color. This is characteristic of batik, and in doubtful cases can determine the authenticity of the work. This texture emphasizes the picture plane in a very natural seeming way.
Another uncertainty must be reckoned with. After each dip it is practically always necessary to iron out all the wax; only rarely does the design allow one part to keep the wax through several dips. Thus, many of the lines and areas of the design are repeatedly waxed over, and it is unlikely that it will be done so exactly that the edges of the design remain sharp; a blurred effect is to be expected.