Methods of Printing

Methods of Printing

1. Block Printing

Block printing is the ancient method of printing designs on the textile material by hand. It is the simplest of the printing methods. In this method, the desired design is carved on a wooden or metal block. The fabric is pinned on a table which is firm, strong and withstands the pressure of printing. The top is made of metal with a resilient surface made of artificial leather. The wooden block is stamped in the print paste or applied on the surface of the block. The block is stamped firmly on the selected part of the fabric. This process is repeated to print the required length of fabric. Multicoloured designs require separate blocks for each colour. Block printing is done mainly in decorative pieces or in expensive linens for upholstery purposes.

Advantages

·               Simplest method of printing

·               Handmade art

·               No special printing equipment required

Disadvantages

·               Tedious and time consuming process

·               Expensive

·               Irregular colour shade

·               Overall production is low

·               Carving of blocks is difficult and laborious.

2. Roller Printing

It is a machine printing method, in which designs are printed on textile fabric by engraved rollers. This method of printing produces over 4000 yards of printed fabric per hour. The cylinder is made up of cast iron which acts as a printing table. The cylinder is covered with many layers of special fabric which has linen in warp and wool in weft for providing resiliency. It is covered with a layer of woollen blanket which provides the perfect surface for printing. The woollen blanket is covered with unbleached cotton cloth which will absorb excess dye. The last layer is the fabric which is to be printed.

The design is transferred onto the cloth by engraved copper rollers. The design roller is arranged in such a way that the paste is applied on the roller and then transferred to the cloth. Number of engraved rollers rotate in contact with larger cylinder in rotation. The cloth is printed at the rate of 1000 to 4000 yards per hour. There are series of rollers each imprinting a different colour on the fabric. The sizes of the engraved cylinders depend on the pattern to be printed. There are different ways of engraving the roller such as hand engraving, machine or mill engraving and photographic engraving. The design roller rotates against the cloth and the design is imprinted. The fabric moves on to the second roller where the second colour is printed. The doctor blade placed in contact with design roller scrapes the excess dye from the surface of the design roller. The printed cloth is dried and then steamed to set the dye.

Advantages

·               Superior to other methods for the production of fine and precise designs

·               Production is faster and accurate

·               All colours required to print can be achieved in one process itself

·               Versatile in colours, pattern and scale

Disadvantages

·               Required skilled labour

·               Laborious process

·               Production cost is more for printing in small quantities

·               Creation of engraved rollers is expensive

·               Time consuming process

·               If rollers are not aligned properly, it results in one or more colours falling out of position

3. Stencil Printing

In stencil printing, the design is first traced on the cardboard, wood, metal or plastic sheets with marker pens or pencils. Using scissors, knife or sharp blade the design is cut out. The uncut portion represents the part that is to be left uncoloured. When cutting the stencil care must be taken that small patterns must be cut through first. If large patterns are cut over or keeping small pattern inside then the smaller designs would be cut away with it. The stencil is placed on the fabric to be printed and the printing paste is applied with stencil brush through its interstices. When printing is repeated, care must be taken that the stencil on face side does not take up dye. Other colours can be applied on the design when the first colour dries. This method is suitable for both fine delicate design and large space design.

Advantages

·               Low budget investment

·               Exclusive designs and intricacy

Disadvantage

·               Unevenness on printing table leads to uneven printing

4. Screen Printing

In this printing method, fabric is spread on large table and design screen is placed on the fabric. The screen consists of wooden frame covered with nylon or silk cloth and the technique is called as silk screen printing. Lacquer is applied on the screen to make the areas except design opaque so that printing paste is transferred through the design only. Based on the number of colours, many numbers of screens are prepared to complete the design. The printed portion should be allowed to dry before placing the second screen. When screens are placed properly, they will produce a complete design.

Advantages

·               Whole width of fabric is printed at once and so the process is faster than block printing

·               Screens can be preserved for future use

Disadvantages

·               Preparation of screen is a time consuming process

·               Preservation of screen needs extra care

·               A small damage in the screen will spoil the entire printing

The design is created by painting or making non-design portions of the screen opaque, thus preventing the print paste from passing through. The areas where the print paste passes through will create a printed pattern. The screen is placed in contact with the fabric to be printed and the print paste is forced through the screen by a squeegee. The squeegee is used to spread the dye evenly through the screen. It is moved across the screen, forcing the print paste through the mesh openings. It helps in making a clean image on the printed surface. A screen is prepared for each colour of the design. There are two types of screen printing namely Flat screen printing and Rotary screen printing.

Flat Screen Printing or Hand Screen Printing

It is done by hand. The design is copied onto a series of very fine, flat screens, one for each colour to be printed. Lacquer or other impermeable substance is applied to all parts of the screen that are not part of its design. Each screen is fitted onto a wooden or metal frame. The fabric to be printed is spread onto a long table. A screen is set over the fabric and the printing paste is poured on the screen and forced through its unblocked areas onto the fabric with a squeegee. The screen is then moved to the next section of the fabric and the operation is repeated until the entire fabric is printed. This process is repeated for each colour of the design. Hand screen printing is time-consuming and limited to short length of fabrics.

Automatic Flat Screen Printing

In this method, the process is automated and therefore faster. Here the fabric moves on a wide rubberized belt. The screens are placed above the belt. As the fabric moves, the screens are automatically lowered to the cloth and the appropriate colour is applied with automatically regulated squeegees. The cloth is dried in an oven.

Advantages

·               Prints upto twenty colours in one run

·               High production rate

·               Produce brighter and cleaner shades

·               Produces designs consisting of squares, circles and ovals

Disadvantage

·               High cost

Rotary Screen Printing

This method of printing is done using machine. The fabric to be printed is moved on a wide rubber belt under the rotary screen cylinders. It is the fastest method of screen printing, with a production of more than 3500 yards per hour. A squeegee in each rotary screen forces the paste through the screen onto the fabric. The cloth is then passed into a drying oven to set the colour and washed.

Advantages

·               Faster method of printing

·               Rotary metal screens are light weight in contrast to the heavy copper rollers and hence they cost less.

·               Operates continuously

·               Production output is higher

5. Transfer Printing

Transfer printing means shifting of a design from one surface to another. In this method, designs made of pigments in paraffin or thermoplastic base can be transferred by heat and pressure to the fabric surface. The fabrics printed by this method become stiff and they are not fast to washing and light. A more effective and easier method of transferring the design intact from paper to fabric is by vaporizing the pigments in the design. Vaporizing can be done by dry heat transfer and wet heat transfer.

Disperse dyes are the only dyes which can be sublimated and used for heat transfer printing. Hence transfer printing is suitable for fabrics which have affinity to disperse dyes. Polyester, nylon and acrylics can be printed by this method. The fabric to be printed is passed through a heat transfer printing machine which brings paper and fabric together and passes them through the machine at about 204°C. Under high temperature, the dye on the printed paper sublimates and is transferred onto the fabric.

Advantages

·               Production cost is low because there is no requirement of post printing treatments

·               There is no wastage of pigment as the design made on paper is transferred to fabric

·               Prints with excellent line details, intricacy and shading can be done

·               Design can be made with many colours

·               Rich and brilliant shades can be generated on woven and knitted fabrics

·               Process is simple and does not require skilled labour

·               High quality prints

·               Less time

·               Environment friendly process

·               Economical for short runs

Disadvantages

·               Selection of dyes is limited

·               Poor colourfastness

·               Not suitable for all types of fabrics

6. Batik Printing

Batik printing is a hand printing method. This is a resist style of printing. In this method, designs are made using wax and the fabric is immersed in the dye bath to colour the unwaxed portions. The wax is applied using various tools such as brushes, tjap and tjanting.

Tjanting is a spouted tool used to draw designs on the fabric with melted wax. Tjap is a pattern made of fine copper strips. The tjap is pressed on liquid wax and applied to the fabric. Wax is applied on both sides of the fabrics. After application of wax, the fabric is dyed to obtain desired colour. Only the portions not covered by the wax will absorb the dye. After the dye has been fixed, the fabric is dried, then boiled and rinsed to remove the wax. It is a slow process.

Advantage

·               Gives an artistic effect to the fabric

Disadvantages

·               Very laborious and time consuming process

·               Dye has to be applied at a temperature lower than the melting point of wax

7. Photo Printing

In this method, the fabric is coated with a chemical that is sensitive to light and photographs are printed on the fabric. The results are similar to the photograph printed on the paper. This is a direct style of printing.