It is often desirable to print a colored design on a fabric that has been already dyed. There are three modern methods of printing patterns: direct printing, discharge printing, and resist printing.
In direct printing the fabric is passed between polished copper rollers, on the surface of which a design has been engraved. When there is to be more than one color in the design a separate roller is necessary for every additional color. The coloring material, which consists of dyestuffs made into a paste, is placed beneath the rollers, a single color for each roller. As each roller rotates it comes into contact with the color and impresses the colored design on the fabric. A strip of steel, called a doctor, removes the color from every part of the roller except that covered by the design.
Discharge printing consists in removing color by means of a chemical from goods already dyed in the piece, thus leaving a white pattern.
Resist printing consists in stamping a chemical on a plain white cloth, and dyeing the cloth afterwards. The chemical makes the dye ineffective on the pattern.