Printing

" The process of decorating textile fabrics by applying pigments dyes or other related material in the form of patterns is called Printing."
Though spinning itself gives a kind of decorative pattern to the fabric, Printing enhances the look and appeal of it. There are many evidences of printing being carried out in the 4th century BC A Printing block at about A.D.300 has been unearthed in the burial grounds of Akhmin in Egypt. In the regions of Mexico & Peru, Pre-Columbian printed textiles have been found. Today, Textile Printing involves the skills of many artisans and designers and has thus become highly sophisticated.

Classification of Printing Styles

Printing styles are classified as direct , discharge or resist

Direct Printing:

This is the most common approach for applying a color pattern. In this style of Printing, colored pastes are printed directly on the cloth and any design may be produced. If done on a white fabric it is called overprinting.

Discharge Printing:

The fabric is first dyed with background color and then printed with a chemical that will destroy the color in the designed areas. Usually a paste contains a reducing agent or reagents to print the design. After Printing, the fabrics need to be washed thoroughly to eliminate the by-products of the reaction. This method of discharge Printing is thoroughly satisfactory, only if properly done.

Resist Printing:

The cloth is first printed with a resist plate, a resinous substance that cannot be penetrated when the fabric is subsequently immersed in a dye. When the cloth is dyed or pigment padded, only those parts not printed with the resist are dyed. In this resist method, the durability of the fabric is not affected.

Methods of Textile Printing

The following are the main methods of Textile Printing:

Block Printing:
Being the oldest and expensive method of Printing, it is no longer commercially viable and is hence used for decorative pieces for the home or in expensive linens for upholstery purposes. Wooden blocks carved with a design are made from solid pieces of wood or metal block. On the face of the block the dyestuff is applied in paste form. The block is pressed down firmly by hand on selected portions of the surface of the fabric imprinting the design as many times as desired on a specific length of cloth. Additional locks must be carved for various designs. After the fabric has been entirely printed with one color, other colors are applied in the same way until the design is complete.

Roller Printing:
Whenever long runs of fabric are to be printed with the same design, the technique of Roller Printing is used. This method is relatively inexpensive when compared to hand Printing. The rollers replace the blocks. Just as there are separate blocks for each color, there are separate rollers here. The design is repeated with each rotation of the roller. The number of rollers to be used depends on the number of colors in the design. As many as 16 rollers can be used at a time. This printed cloth is then passed through a drying chamber and later into a steam chamber where the moisture and heat sets the dye.

Screen Printing:
This may be a hand operation or an automatic machine process. Firstly the cloth is laid on a Printing table, gummed in position or pinned to a back gray and then the design is applied through a screen made of silk or nylon gauze stretched over a wooden or metal frame, on which the design is for one color has been produced. This is usually a photographic process. A screen is placed over the fabric on the table against registration stops, so as to ensure accurate fitting of the pattern. Print paste is poured on to the screen edge nearest the operator and is spread with a squeegee over the surface of the screen so that color is pushed through the open parts. The screen is thus moved until one color has been applied to the cloth. The process is repeated with different screens, for the application of other colors.

Other Methods of Textile Printing

Heat Transfer Printing:

This is the newest method of printing fabrics by transferring designs to fabric from special pre-printed paper.

Duplex Printing:

The fabric is printed on both sides in Duplex Printing. Thus in this method a clear outline is produced on both sides of the fabric. The design is applied so skillfully by the Printing cylinders that the result may be mistaken for a woven design.

Spray Printing:

This method of Printing involves the application of colors from spray guns through stencils and has limited but occasional profitable use.

Resist Printing:
The fabric is dyed with a tannin mordant paste and then the desired areas to be used for the motif are stripped of the covering, leaving the areas white. The fabric is then piece "dyed" and some or all of the white areas are colored by this method of printing.

Print-On-Print

When the discharge or resist methods of Printing are not called for, this procedure is used. Each color used must have its own color roller and provide clean and clear effect. Many effects are possible by the use of this method. This is an ideal method with regard to price and high production.
Photographic Printing:

Photographic printing can be transferred to fabric by the use of photo engraved rollers. Various ways are used to obtain the result, all adapted from color printing on paper. Red, Yellow and blue, the primary colors are much used to obtain a host of color-effects.

Shadow Printing:
Chintz, cretonne, ribbon and some silks are woven with only the warp printed so as to provide mottled  effects when woven with a white or light colored filling. These indistinct motif fabrics are reversible.

Stipple Printing:
Printing of small dotted effects set in among spaces or bare areas of a printed motif. Used chiefly in novelty effects.

Warp Printing:
Warp yarn is printed on a beam and then it is rewound onto a second beam which is placed in the back of  the loom and made ready for the weaving operation. Warp prints give a melange or mottled effect when  woven with plain filling, white or in some light color. Rather popular are coverlets, some dress goods,  counterpanes, bedspreads, hangings etc.