Subject: Dyeing and Printing. Unit 8: Styles of printing. Quadrant 1 e-text

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Shana Emmeline Summers
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1 Subject: Dyeing and Printing Unit 8: Styles of printing Quadrant 1 e-text Learning Objectives The learning objectives of this unit are: Describe the process of block printing, hand screen printing, automatic flatbed screen printing, automatic rotary screen printing, heat transfer printing. 8.1 Block Printing It is the oldest and simplest method of printing. The designs to be printed are first carved on wooden timber. Colour in the form of thickened paste is applied to the raised parts of the block, and an impression of the design is obtained by stamping the block by hand, with a wooden hammer on the cloth. Each shade of a colour requires a separate block. Design possibilities. Designs in any number of colours and on any scale can be reproduced. Block prints possess richness, fullness and purity of colour. There is no limiting factor in respect of size of repeat. The prints produced by this method are of great decorative value. Disadvantages. The main disadvantages are: The method is slow and production cost is high. It is not possible to obtain fine, sharp outlines. Repeat marks are visible, due to separate impressions of the block. Large repeat size is not possible. Since it is a manual method, it is quite laborious. 8.2 Hand Screen Printing The screen is made up of tightly stretched nylon gauze. The design is transformed on the screen with photo emulsion.

2 The screen is placed above the cloth, and printed with rubber squeezes manually. After printing each colour, the print is dried by bottom steam pipes or hot air blower. After printing, the fabric is dried wel,l and rolled on a cylindrical shaft. Advantages. It is best suited for economical printing of small lots. The equipment is simple equipment, easy to install, and requires less maintenance. It is also inexpensive. Damages can be easily controlled. Unlimited colours can be printed. Maximum possible repeat size is possible. Cut- garment prints is possible. It is adaptable for both woven and knitted fabrics. Disadvantages. Half tone designs, fine-line paisley prints and lengthwise stripe designs are not possible. The production is slow, and is time consuming. It has low productivity. Scope for lot-to-lot variation. It is uneconomical for large production yardage. 8.3 Automatic Flatbed Screen Printing The fully automatic flat printing machine consists of three units: Fabric feeding unit Printing unit, and Drying unit with plaiter In the fabric feeding unit: The cloth from the batch roll is taken through guide rolls, tension bars, and fabric guider and is pressed to the blanket by means of feed roll.

3 The Printing Unit: consists of an endless synthetic rubber blanket, which supports the fabric during printing and returns to the feed position after washing. Printing Station: According to the capacity of the machine, 8-16 printing stations are available. Before the start of printing, the screens are positioned according to the repeat and order of printing. The cloth is fed, and printing stations are switched on. Printing is done sequentially, at various printing units, and then leaves to the drier unit. There it gets dried, and is finally plaited on trolleys. Large repeat size (up to 60 ) possible. Over all and cross border designs are printed. Better colour definition than roller prints and it is equal to hand screen. It is adaptable to all woven and knits. Rapid changeover of designs is possible. It has the Best machine registration. Limitations: However, this system has certain limitations. The cost of screen preparation and special mountings is more costly than hand screen. It is not adaptable to low yardage. Half-tone designs, Fine-line paisley prints, and lengthwise stripes are not possible. 8.4 Automatic Rotary Screen Printing Working principle: The respective screens are mounted on the rotary heads.

4 Selected squeegees are inserted and connected to the respective colour pumps. The fabric to be printed is fed to the blanket, and gets printed by the respective screens continuously. The printed fabric is conveyed through the dryer and plaited. It is possible to print at speeds up to 80 meters per minute. Printing is continuous. Up to 40-inch repeat size are possible and larger than roller printing, but smaller than flatbed screen. Lengthwise stripe effect is possible. Fall-on designs is possible. It is adaptable to all wovens and knits. It provides cleaner, and brighter colours than roller print. It has excellent colour definitions, but less than flat bed screen prints. Rapid change over of designs is possible. It is efficient for long runs and moderately small (1000 yards) runs. Limitations. Cross border designs and Fine-line paisley prints are not possible. Half tone designs are not as effective as in roller printing. It is uneconomical for short runs. Colour penetration is difficult for thicker fabrics. Colour consumption and wastage is higher. Design repeat size is smaller than flat bed printing.

5 8.5 Heat Transfer Printing Working principle: In this method, the vapour phase transfer takes place by heating under pressure at c for 20 seconds. The dye sublimes under heat from the paper, and is absorbed by thermoplastic substrates. The colouring matter, and the thermoplastic binder are transferred to the fabric, under heat and pressure. After the release of the film, the paper is removed when the design is completely transferred to the fabric. It produces bright, sharp, clear fine-line designs. It has the ability to print cut garment parts and small items. It is adaptable to long and short yardage runs. Rapid pattern changeover is possible. Simple, low-investment installation steamers, washers, dryers, dryers, etc. are not required. It has the fewest seconds of all printing processes. Heat setting is also accomplished. Limitations. The Lead-time for paper preparation can cause problems in high fashion markets. The fiber content in fabric should be minimum 50% synthetic Fiber. Cellulose s and protein fibers cannot be printed. Over print only on pastels, or else it will not completely cover the original colour. 8.6 Conclusion To summarize, in this unit you have learn the techniques of block printing, hand screen printing, automatic flatbed screen printing, automatic rotary screen printing, and heat transfer printing.

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