Carolyn Sue Jarrell, aged 12, of Chesapeake, W, Va., for her question:

How do they put designs on material?

There are several ways to put designs on cloth. One way is to spill a blot of ink on your dress. Another way is to drip soup on your blouse. But these designs are not artistic. What's more, they wash out ‑ we hope.

Colored designs on material should be wash‑proof. Special dyes are used for the job. Nowadays, most of these dyes are man‑made. The chemists can make 1500 different colored dyes for cloth from coal tar. Coal tar is made from coal. The coal is heated in closed ovens. Different substances are driven off at different temperatures. Each dye substance can be collected in a separate container.

The background color of the cloth is usually done first. This is called stock dying. The raw fibers of the material may be dyed. The woven threads may be dyed. Or the yard goods may be dyed whole in a big vat.

The colored designs may be put onto the cloth by handwork. This is expensive and takes time. They may be put on by rolling machines. This is the fast and inexpensive way to put designs onto cloth.

Maybe you have done stencil work. You cut an openwork design in heavy waxed paper. Place the cutout flat on the cloth. Use a stiff brush to stipple through the holes. This is something like the expensive silk screen color printing.

The silk screen is a, section of silk held tight in a wooden frame. The design is traced onto the silk. The background is painted in with lacquer. The design is left clear. The screen is then placed flat on the cloth. Color is pressed through the design section. The lacquer keeps the color from passing through the background. A separate silk screen is needed for each color used.

Block printing is also done by hand. The design may be carved on wood or etched on metal. One block is cut for each color to be used. Each block is then covered with its proper dye. It is then carefully pressed into place on the flat material.

Cloth printing machines use blocks curved to fit onto rollers. These designs are etched onto metal. The cloth runs through the rollers like paper running through a printing press. A different roller is needed to apply each dye. These rolling machines can decorate hundreds of yards of material in a day.

Sometimes designs are woven right into the cloth. Woolen plaid designs are woven with different colored threads on the loom. Beautiful brocades are also woven on the loom. These designs call for complex machinery. Such woven designs are usually expensive to make.