How to use fabric emulsion

Printing is a process of decorating textile fabrics by application of pigments, dyes, or other related materials in the form of patterns.

Block printing

The wood block with embossed design is made of strong wood, or a material that glues fine-grained wood with cheap wood. When a large area is included in the design, these areas will be recessed and the space will be filled with hard felt. Thin wires are usually made of copper, while other effects are made by interlacing copper tape and felt. In order to facilitate the registration of continuous printing or offset printing, each block has a plurality of spacing pins, which are arranged to coincide with well-defined points in the pattern. The cloth is printed on the table, which is covered with fabrics or blankets of several thicknesses, and the entire table is covered with thick, tightly stretched synthetic rubber. Spread the cloth to be printed on the rubber, spread it in place or nail it to the back cloth fixed on the table. Apply the color evenly to the block, and use the handle of a small heavy hammer or mallet to imprint the pattern on the fabric to be printed to help the paste penetrate. Then, apply more colors to the block and repeat the process with a pitch change pin to obtain true registration. After the fabric is completely printed in one color, apply other colors in the same way until the design is completed. Although block printing has become too laborious and expensive for commercial use, some of the most beautiful prints are made in this way.

Roller printing

This technique is used whenever long runs of fabric are to be printed with the same design. The modern machine, based on one originally devised in 1783, consists of a large central cast-iron cylinder over which passes a thick endless blanket providing a resilient support for the fabric. Backing fabrics, called back grays, are placed between the blanket and the fabric to prevent undue staining of the blanket. Although formerly made of cotton fabric, most modern back grays are continuous belts of nylon. The blanket and back gray are appropriately tensioned, so that the fabric moves through the machine as the central cylinder rotates. Engraved printing rollers, one for each colour, press against the fabric and the central cylinder. The pattern on the roller is etched on the surface of a copper shell supported on a mandrel. High-quality engraving is essential for good printing. Each printing roller is provided with a rotating colour-furnishing roller, partially immersed in a trough of printing paste. Finely ground blades (doctor blades) remove excess colour paste from the unengraved areas of these rollers, and each also has a lint blade. The printed fabric passes from the main cylinder and through a drying and steaming chamber to fix the colour. Although this machine prints only one side of the fabric, the Duplex roller machine, essentially a combination of two roller machines, prints both sides. Modern printing machines are smooth-running precision machines fitted with carefully designed roller bearings and hydraulic or pneumatic mechanisms to ensure uniform pressure and flexibility. Pressure is regulated from an instrument panel, and each roller is controlled independently. Automatic registration is effected by electromagnetic push-button control, and modern electric motors provide smooth-running, variable-speed drives. The washing of back grays and printer’s blankets has also been automated.

Spray printing is the application of colour from spray guns through stencils and has limited but occasionally profitable use.