Printing is a part of wet processing technology which is carried out after pre-treatment of fabric or after dyeing of fabric for producing attractive designs on fabric or other materials. Printing is described as localizing dyes or pigments which are applied locally or discontinuously to produce various attractive designs on fabric. Main objectives of printing are producing attractive designs with well defined boundaries made by the artistic arrangement of a motif or motifs in one or more colors. If dyes and pigments are applied properly on fiber, printed fabrics are protected from friction and washing. A strong bonding is formed between dyes and fiber.

Steps of textile printing:
Firstly, pre-treat fabrics before printing.
Use printing ingredient to prepare printing pasts. Printing performance depends on a well printing paste.
Use any printing methods to make an impression of the print pasts on the fabric, which is required.
Carry out steaming on printed fabric to fix the printing paste on the fabric.
After-treatment process neutralizes printed fabric.

Styles of printing: There are three different styles of printing: direct style of printing, discharge style of printing (including white discharge and color discharge) and resist style of printing (white resist and color resist)

Methods of printing: Using different instrument carry out printing. Use different method to produce impression on fabric. Demands of users vary methods which rely on the type of materials and the purpose of end product usage.

The followings are the methods applied for textile printing operation.
Block Printing
Burn-out Printing
Blotch Printing
Digital printing
Duplex Printing
Engraved Roller Printing
Electrostatic Printing
Flock Printing
Ink-jet Printing
Jet Spray Printing
Photo Printing
Rotary Screen Printing
Screen Printing (Flat Screen)
Stencil Printing
Spray Printing
Transfer Printing
Warp Printing
Special Methods (Tie dyeing and Batik Printing)

In the early of history, printing was carried out by hand. Nowadays, different modern techniques are widely used for printing, which are controlled by computer. Graphics design is also widely used. Textile machines improve printing methods a lot.

Pigments are mainly synthetic organic materials which have no affinity on the cotton fabric. For this, binder is used for making film on the surface of pigment so that produce a 3-dimensional cross linking between fibers and pigments. After drying, curing is carried out under 150-180℃ for fixing the pigments on the surface of cotton fabric. Price of pigment printing is lower than that of other printing process.

The following are the process of pigment printing on cotton fabric:

Recipe: Recipe can be changed due the depth of color
Thickener: 2%
Binder: 8%
Fixe: -2%
Water: 90%

Fabric Pre-treatment
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Table preparation
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Fabric plaited on the table
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Pigment printing paste apply with the help of screen
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Curing at 160℃ (belt speed 6.50 m/min)
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Delivery

Printing is a method of wet processing technology which can produce various types of decorative and attractive designs on the surface of the fabric.

Process of printing 100% cotton fabric:
Printing is the most used process. Process of printing varies, due to the types of fiber. When printing natural fibers such as cotton, wool and silk, the impurities on natural fibers must be removed before dyeing and printing. The process is also called as pre-treatment process. After printing, finishing process is carried out for improve the out looking of the printed fabric.

Inspection of grey cloth
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Stitching
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Shearing or Cropping
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Singeing
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Desizing
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Washing
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Scouring
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Bleaching
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Washing
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Stentering
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Printing
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Steaming
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Washing
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Calendaring
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Inspection
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Folding or Rolling
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Packing

Emboss printing also called as pub printing, differs from pigment printing, foil printing, flock printing or any others dyes printing, which is particularly used for making logo or other decorative purpose. In this printing process, printing is done by embossing the printing paste on the textile materials.

Process of emboss printing (pub printing)
Recipe: This is a sample recipe for emboss printing process.
Rubber paste: 49%
Pub/Emboss: 49%
Fixer: -2%

Fabric pre-treatment
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Table preparation
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Fabric plaited on the table
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Apply printing paste by screen (3times)
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Hanging for 15min
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Curing at 170℃ (belt speed 3m/min)
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Delivery

Emboss printing is mainly used for business card which can produce various types of glossy design.

Color fastness: Color fastness means the resistance to changes when subjected to particulars of condition which is specified in terms of changes and expressed in terms to the magnitude.

Color fastness to washing is used for measuring the fastness of colored materials, which is carried out in dyeing lab. Based on different measuring procedures, the test can be varied. For quality assurance system, a record is maintained for dyed fabrics or finished fabrics. Computer color matching system (CCMS) can save the record.

Required materials: The followings are necessary for wash fastness test:
1. Sample size 40 x 100 mm
2. Multi-fiber at 40 x 100 mm
3. ECE detergent (WOB)-4g/L
4. Sodium Perborate (Na2BO3.H2O2-1g/L)-1g/L
5. Distilled water
6. Noramal cold water
7. Steel balls

Required instruments: Various types of instrument are required for measuring color fastness to wash, including rota wash, scissor and stitch machine.

Steps for measuring color fastness to wash: Color fastness to wash is an off-line quality assurance.
1. Cut sample and multi-fiber at 40 x 100 mm.
2. Take the sample with 50 ml ECE detergent (WOB) and 50 ml Sodium per borate. For marks and Spencer, take the solution by formula: (Sample fabric + Multi-fiber weight) x 50 ml.
3. Keep the sample under 60℃ for 30 minutes in Rota wash machine.
4. Rinse the sample twice with cold water.
5. Dry at 60℃ by hanging or by Flat iron pression but temperature should not be more than 150℃.
6. Dry the specimen and the change of shade & degree of staining is measured by Grey Scale and Staining Scale.

In dyeing and finishing section, quality assurance system is used to measure the quality of dyed fabrics. Through checking the shade of dyed fabrics, the fastness properties can be worked out. Dyed fabrics will be issued with quality certificate, for them having good fastness properties.

The quality of dyed fabrics is assured in laboratory, dyeing section and finishing section.

In laboratory:
1. Receive swatch card from buyers according to their requirement.
2. Dye sample by manually or CCMS.
3. Dye sample until matching with swatch card.
4. Fastness & other tests of fabrics can be also carried out.

In dyeing section:
1. Dye sample in dyeing machine and dyeing shed, matching with the approved sample.
2. Move to bulk production, if the result is matched with approved sample.
3. During dyeing, take the samples when accurate shade matching accurate shade. The interval is lasted fro 30-40 minutes.
4. Collect dyeing sample which having been softened.
5. Last of all, collect sample from fixation & matched.
6. Allow fabrics to be finished.

In finishing:
1. Using a series of finishing machines maintains correct width, softness and appearance according to requirements.
2. Test samples for several times for GSM, shrinkage & fastness properties.
3. Inspect fabric and prepare for delivery.

A quality assurance manager runs quality control department to ensure the quality of textile products during manufacturing. Quality of textile produces is checked in every step of manufacturing. For quality assurance system diagram, different international quality standards are adopted. Q.C department also helps CCMS test the quality of a textile material.

The followings are the quality assurance system diagram for textile products.
Yarn processing
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Yarn test
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Pass — Fail
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Knitting Send to spinning mill
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Grey fabric inspection
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Pass — Fail
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Grey store Send to store as reject
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Batch making
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Dyeing
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Dewatering
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Drying / stentering
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Compacting
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Fabric checking
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Lab Inspection (Shade)
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Pass — Fail
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Delivery Send to store as reject
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Send to concern Department

Textile Testing Quality Control (TTQC) lap is used to ensure the quality of textile products. TTQC lap plays a key role in the evaluation of textile products. Nowadays, producers are expected to supply qualitative product.

In textile industry, quality is assured at the every step of production. From the raw materials to the finished goods, quality control department assures the quality. Quality must be assured in fiber selection, yarn production, fabric manufacturing, wet processing and apparel manufacturing. The quality of dyestuff and chemicals which is used in dyeing, printing and finishing also should be checked. Mostly, quality control department gives a quality pass certificate so that finished products can be exported.

Educational institutes, research institutes for teaching the quality evaluation system and research have TTQC lab, so does as testing the quality of the textile products. Some TTQC labs are set up for commercial purpose. Some quality standardizing group also set up TTQC lab for testing the quality. TTQC lab also ensures the quality of the dyes and chemicals in dyestuff market.

Types of TTQC lab for quality assurance of textile products:

There are various types of TTQC:
1.Textile testing and quality control lab (TTQC Lab) in the Industry.
2.TTQC lab in the educational institute.
3.TTQC lab in the research institute.
4.Commercial TTQC lab.
5.Port TTQC lab.
6.TTQC lab in the standardizing house.
7.TTQC lab in the buying house.
8.TTQC lab in the dyestuff market.
9.TTQC lab in the arm force or defense department.