TEXTILE DESIGN / PRINTING / DECORATION

 

Introduction

Printing can be defined as the localized application of dye or pigment in a thickened form to a substrate, to generate a pattern or a design. It is an important economic way of producing colourful effects on fabrics and to lesser extent on yarns. It is a highly industrial art of long history. Printing is essentially transfer of dye or ink onto a fabric using pressure. It is comparable to textile dyeing. In printing process, dye (dyestuff / pigment) is applied or printed onto the textile material. However, in contrast to dyeing, only a limited surface of the textile is coloured.

Printing techniques and styles known to the expert include the following:

i.                    Block printing

ii.                  Roller printing

iii.                Duplex printing

iv.                Discharge of extract printing

v.                  Resist printing

vi.                Stencil printing

vii.              Screen printing

viii.            Rotary printing

ix.                Transfer printing

x.                  Warp printing

Discussions on the basic principles underlying the major fabric printing methods are presented in this section.

1.      Relief Method

In this printing technique, the fabric receives colour from the raised surface of the printing material with pressure. Examples are Block printing, and Letter press material of paper printing.

 

2. Engraved (or Intaglio) Method

 

 The colour is held in the incised lines and the pattern is transferred from them to the cloth by pressure. Roller printing and copper plate are typical examples of this method of printing.

 

3. Screen Printing

Screen printing is basically a stencil printing technique. It is a developed version of the stencil process. A screen refers to wooden, plastic or metal frame with a mesh fabric (man–made or natural) like silk mesh or organdy stretched taut over it. Portions of the mesh have the holes blocked off with P.V.A. material (non–printing area) and the printing paste is forced through the open printing areas by a rubber or metal blade called ‘squeegee’ to effect print on the fabric beneath it. Flat-bed screen printing and rotary screen printing styles are examples of this method of fabric printing.

 

4. Lithographic Method

Lithography is an image transfer method in which an oil-receptive image area accepts an oil-based ink which is transferred to a rubber–covered cylinder and then transferred onto the printing surface. This printing technique is also called Planographic printing or Offset lithography.

Lithographic method is rarely applied to textiles but used extensively for paper printing. With this process, there is no difference in depth between the printing and the non-printing surfaces.

The design is prepared in greasy ink upon a porous surface or roughened metal. The dampened surface is then supplied with the printing ink. The clean portions of the plate roller repel the oil-based ink while the greasy portions accept the ink for the printing. Impressions are then made on the fabric with the inked plate or roller.

 

5. Sublistatic (or Transfer) Method

Heat transfer or sublistatic printing is a method of printing in which special dyes are first printed onto a paper before the designs are transferred from the paper to the fabric. The transfer of colours takes place as the colour sublimes through vapourisation. This is achieved by rolling pressure and at a high temperature (424°F) or (200°C). This printing method is used on synthetic fabrics with the use of mostly disperse dyestuffs.

 

Fabric Printing Techniques

i.                   Block Printing

Block printing is the simplest of the printing techniques and requires only a limited technology. It is basically hand printing method and the oldest method of printing designs on fabrics. It is not preferred for printing fabrics on commercial quantities by most experts as compared to techniques like roller printing due to its slow rate of production.

Some experts assign 2000B.C. as the date for the discovery of block printing for fabric decoration at Caucasus in Russia. Blocks that were used in printing textiles have been recovered from Egyptian graves of the 4^th century A.D.

In block printing, the print paste is applied to the textile material from a raised surface on a wooden base or block. It is thus a relief method. In the early and mid-18^th century, simple wood block was used for line work and small shapes. The design is transferred onto the block and the background and non-printing areas cut to a depth of 1-2cm according the type of shape and type of fabric to be printed.

Fine clothes need less deep cutting. Areas over 5cm in width do not print well because the wood does not hold the water-based dyes easily enough to give a regular result. When bigger areas are to be printed, a colour block is used.

Thick felt is pressed into the center of the motif so that it is level with the wooden outline. The wood outside the shape is then carved away leaving a firm area of pattern in felt with a supporting wall of wood. The felt holds the dye readily and allows the block to give out its colour evenly to the fabric.

To make hand–blocked prints, the following steps are used:

i.        Carve the design onto a wooden or metal block.

ii.      Apply dyestuff in paste form to the design on the face of the block.

iii.    Press down the block firmly by hand on selected portions of the fabric to print the design.

iv.    Repeat the printing at other predetermined areas on a particular length of fabric, if desired by the designer.

v.      Use additional carved blocks to print the second, third, or any additional colour if needed for the design. Each colour in the design requires a separate block for the printing. The more the colours used, the more expensive the hand–blocked print will be, because of the enhanced beauty of the design as well as the labour involved in the hand printing.

 

Finishing of blocks for printing

i.        Apply a waterproof varnish coating to the wood to preserve it as long as possible.

ii.      Make two finger–grip holes in the back of the block to enable the printer pick it up easily and also hold it securely.

iii.    Produce guides for ink printing by fixing pins at corners or specific portions of the block to help in correct registration and repeating of motifs.

A wood block for fabric printing

 

Mechanisation of Block Printing

Although block printing was popular, it was loosing grounds as a result of the much faster cylinder or roller printing. Many attempts were made to mechanise the process to compete with the new methods. Surface roller machine invented by Ebinger (a Frenchman) in 1800 AD and Perrotine produced in 1834 AD by Perrot are two known block printing machines.

 

ii.     Roller Printing

Roller printing is the machine method of printing designs on cloth by engraved rollers. It turns out colour –designed fabrics in vast quantities at the rate of thousands of yards an hour. Roller printing is also referred to as Intaglio or Machine printing. The printing areas are recessed below a smooth surface. The engraving of patterns unto the copper rollers in itself is a highly technical and lengthy process. The technique of roller printing is especially used for very large batches but face great completion from rotary screen printing in recent times. It has also resulted in the less use of the block printing technique. Block printing is comparatively considered to be time consuming and too expensive to use.

 

Basic Principle of Roller Printing

In roller printing, colour in the form of a paste situated in the engraved portions or grooves of copper printing rollers is transferred to the fabric. The fabric passes over a large central cylinder or pressure cylinder, covered by a lapping with an endless printing blanket running over it. On it runs a backgrey which is in direct contact with the fabric to be printed.

The pattern or design to be printed on the fabric is engraved on the copper rollers. The engraved portions receive dyestuff through the furnisher which takes up the printing paste from a colour box. Each printing roller receives only one type of dye and transfers this specific colour to the cloth as part of the entire pattern which must eventually be obtained on the fabric.

Engraved roller printing with one colour

Once the rollers have been prepared, they are installed in exact position on the machine. The fabric to be printed moves over a rotating drum. Behind it is placed a layer of fabric (back grey) that absorbs excess dye and keeps it from being deposited on the drum. The design roller also rotates, moving against a rotary brush (furnishing brush or roller) that rotates in a tray of printing paste. This brush furnishes colour to the roller. A doctor blade scrapes off excess dye from the roller, and the roller then rotates against the cloth and the design imprinted. The fabric moves on to the second roller where a second colour is imprinted and so on in a continuous printing operation.

The rollers must be aligned perfectly for proper registration of the design on the fabric. If rollers are not positioned correctly, the resulting print will have one or more colours that do not fall in quite the correct position, causing the printing to be distorted. The printed cloth is dried immediately and then passes to a chamber in which steam or heat sets the dye.

Roller printing is superior to other types of printing for fine or precise designs. However, roller printing requires skilled labour and much heavy manual work in the changing of the colour troughs and rollers. The initial investment of time and money in the preparation of rollers for roller printing and in setting up the machine are such that production of small quantities of printed cloths are not economically viable. Roller printing is used more advantageously for lengthy runs of the same pattern. However, the introduction of rotary screen printing technique has led to a decline in the use of the engraved roller printing technique.

  iii.  Duplex Printing

Duplex printing is done on a special machine that prints designs on both sides of the fabric at the same time. The fabrics may be passed through the roller printing machine in two separate operations or through a duplex printing machine in a single operation. Duplex printing produces an equally clear outline on both sides of the fabric. The design is applied so skillfully by careful registration of the printing cylinders that may be mistaken for a woven design. This process is seldom used now, for it is expensive to create duplex prints.

Duplex printing machine