Printing on Textiles

7/31/2019 Printing on Textiles

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Textile printing can often be consideredpart of the finishing industry. Fabricprinting is an art form and can be done in

many different ways.It is essentially a decorative pattern ordesign that is applied to constructed fabric.


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Textile printing is an ancient art form found on cloth inEgyptian tombs dating to about 5000B.C. Greek fabricsdating from the 4th century B.C. have also been found.

Block prints were first seen imported from India to theMediterranean in 5th C B.C.

During the renaissance, Indian chintz was imported toEurope, where it became popular and was imitated. France

became a leading centre of this type of cloth productionduring that time. Stencil work, a highly developed form ofprinting from Japan was another early discovery of applyingpattern to fabric.


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Roller Printing

Flat (Silk) Screen Printing

Rotary Screen Printing

Block Printing

Heat Transfer Printing

Dye Sublimation Printing

Resist Printing


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This process involves a print paste (like a thick paint) thatis applied to an engraved roller, and the fabric is guided

between it and a central cylinder. The pressure of theroller and central cylinder forces the print paste into thefabric. Because of the high quality it can achieve, rollerprinting is the most appealing method of printing designer

and fashion apparel fabrics.


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Long runs of the same

fabric design are producedon a roller print cylindermachine operating atspeeds between 50 and100 yards a minute. Asmany as 10 differentcolors can be printed inone continuous operation,but each colour must have

a separate roller.

The design is cut into the

surface of copper rollers;by varying the depth of theengraving on the roller theshade depth can be altered.Sharpness of line and finedetail can be achieved thisway. A typical printingmachine has a large paddeddrum or cylinder, which is

surrounded by a series ofcopper rollers, each with itsown dye trough and doctorblade that scrapes away

excess dye.


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The tubular screens rotate at the same velocity as thefabric, the print paste is distributed inside a tubular

screen, which is forced into the fabric as it is pressedbetween the screen and a printing blanket (a continuousrubber belt). It picks up colour from the engraved area ofeach roller in sequence. The printed cloth is driedimmediately and conveyed to an oven that sets the dye.Knitted fabric is mostly printed in this method as it doesnot pull or stretch the fabric.


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In flat screen printing, a screen on which

print paste has been applied is loweredonto a section of fabric. A squeegeethen moves across the screen, forcingthe print paste through the screen andinto the fabric. The screen is the image

carrier made from a porous meshstretched tightly over a metal frame.

A positive stencil using negative artwork is produced on the mesh either

manually or photo chemically. Ink isthen forced through the fine meshopenings using a squeegee that isdrawn across the screen allowing

print paste to pass through only theareas where no stencil is applied.


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Block printing is a traditional process dating back to Indiain the 12th century. Wooden blocks made of seasoned teakin different shapes and sizes are cut by trained craftsmen.Each block has a wooden handle and two or three holesdrilled into the block to the passage of air and release ofexcess print paste.

Fabric is stretched over a printing table and fastenedwith small pins. Printing starts from left to right, first

the colour is evened out in the tray and then the block isdipped in. Then the block is applied to the fabric withcareful registration and pressure is applied.


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Multiple colour designs are labourintensive and require a lot of skill to

register the prints exactly.

Colour variation is hard to avoid withthis method as print ink can vary inquality of depth or colour.

The Japanese took woodblock printing to new levelsand developed unparalleledskill in the construction offine delicate prints.


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This is essentially transferring an image to fabric from apaper carrier. When heat and pressure are applied tothis paper the inks are transferred. Some transfers aretopical, and the image sits on the surface of the fabric.Other transfers are absorbed into the fibres of the

fabric.

Heat transfer printing is clean andenvironmentally safe. The only by-product is thepaper carrier. It is the perfect print method for

short run and sample production, but can also beused for batch production as well.


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Dye sublimation allows photo lab quality picture printing.During the dye sublimation printing process, an image isdigitally printed in reverse with dye sublimation toners orinks onto media. That image is then placed on top of afabric and subjected to high heat and pressure to form aheat press. The dye sublimation toners or inks sublimate the inks go from a solid state to a gaseous state withoutbecoming liquid in between and flow into the fabric,dyeing the threads.

This creates a gentle gradation of colour and doesnot distort or fade over time.


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Discharge printing is one method of resist printing andinvolves using a chemical paste called a disperse dye. Itmust be used with a reactive dye as a ground colourfor the process to work. It also has to be cured orfixed with steam so the dye reacts with the fabric and

causes a colour reaction. Discharge printing producesthe brightest, lightest prints on dark-colouredgarments and can be very striking. This method canonly be used on natural fibres and fabrics that will

discharge colour.Another method of resist printing is Batik. Naturalmaterials such as cotton or silk are used as they absorbthe wax that is applied in the dye resisting process. The

fabrics must be of a high thread count (densely woven)for best results.


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Although experts disagree on the origins of Batik, itis very popular in Indonesia and Africa.

The cloth that is used for batik is washed and boiled

in water many times before the wax can be applied sothat all traces of starches, lime, chalk and othersizing materials are removed. Before modern-daytechniques, the cloth would have been pounded with awooden mallet or ironed to make it smooth and suppleso it could receive the wax design. The designer usesa tjanting(wax pen)to draw the design on the cloth.The wax is kept fluid in a melting pot.


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After the wax has been applied, the fabric isready for the dye bath. Today most batikfactories use large concrete vats, above the vatsare ropes with pulleys that the fabric is drapedover after it has been dipped into the dye bath.The amount of time it is left in the bath

determines the hueof the colour (longer fordeeper colours)


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Printing techniques are renowned for their damage to the

environment and the health of the workforce producing them.There is a lot of washing preparation done to the fabricbefore it can be printed on and this sends chemicals into theair and water and pollutes the outside environment. A typicalprocess will often include sequestrates, alkalis, bleachingagents, stabilisers, catalysts, crease-resisting agents, aciddyes, exhausting agents, soaping agents and softeners.Probably 2030 chemicals per process. Harsh and hazardouschemicals are used in the dyeing and printing methods of

fabrics and toxins like carbon monoxide, carbon dioxide,sulphur dioxide and zinc oxides carcinogenic are commonlyfound in these processes. Transfer printing is the mostenvironmentally friendly form of printing onto fabric and also

the most cost effective. As a result it is fast becoming thetextile manufacturers choice for the future.


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In piece dyeing, which is used primarily for fabrics that are tobe a solid colour, a continuous length of dry cloth is passedfull-width through a trough of hot dye solution. The cloth thengoes between padded rollers that squeeze in the colour evenlyand remove the excess liquid. In one variation of this basicmethod, the fabric, in a rope-like coil, is processed on a reelthat passes in and out of a dye beck or vat.

The most commonly used processes forimparting colour to cotton are piece dyeingand yarn dyeing.

Yarn dyeing, which occurs before thecloth is woven or knitted, is used toproduce gingham checks, plaids, wovenstripes and other special effects. Bluedyed warp yarns, for example, arecombined with white filling yarns in

denim construction.


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One of the most commonly used yarn-dyeing methods ispackage dyeing. In this system, yarn is wound on perforated

cylinders or packages and placed on vertical spindles in a rounddyeing machine.

Dye solution is forced alternately from the outside of thepackages inward and from the inside out under pressure.

Computers are used increasingly in dyeing processesto formulate and match colours with greater speed

and accuracy.


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Finishing, as the term implies, is the final step in fabricproduction. Hundreds of finishes can be applied to textiles,and the methods of application are as varied as the finishes.

Cotton fabrics are probably finished in more

different ways than any other type of fabrics. Somefinishes change the look and feel of the fabric, whileothers add special characteristics such as durablepress, water repellency, flame resistance, shrinkagecontrol and others. Several different finishes may be

applied to a single fabric.


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Olduvai stone chopping tool


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The discovery of this stone tool helped

to prove that humans evolved in

AfricaThis chopping tool is the oldest humanly made object in the British Museum. It

could be used for many purposes including chopping bones, plants and wood.By using a stone hammer to knock flakes off of a pebble our ancestors couldmake a tool with a sharp, functional edge. Olduvai is part of the great EastAfrican Rift Valley torn open by massive earthquakes. Many skulls and bones

of our early ancestors have been found along this valley.

Can we be human without objects?

The invention of the first tools is one of the most important moments in humanhistory. Making, using and sharing things played a key role in developinghuman behaviour. The ability to make tools allowed humans to adapt to new

environments and out-compete other animals. Gradually it would lead tohumans becoming the most successful animal in the world. All moderntechnology began with these first chopping tools


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Richard Leakey

"To me it's a question of being able to

look backward and give the present a

root... To give meaning to where we aretoday, we need to look at where we've

have come from." (Richard Leakey, in

National Geographic, February 1998)


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Kusuma Barnett, Head of

Volunteers, British Museum When you look at this object you might ask yourself what is it and why is it in the Museum? If you

were able to hold it in your hand as I did in 2005 and find how comfortably it fits into your palm (likea computer mouse!), you would know straight away that this was made to be held by a person.

I never thought I would have the opportunity to handle something made nearly 2 million years ago. Itwas just like touching history.

I was one of a team of volunteers which helped visitors to the Museum handle this object. Most ofour visitors were just as excited as I was at being able to hold something that was so old.

Some visitors were close to tears. Some were sceptical: was it really made by man and not a piece ofrock? I was able to show the visitors the sharp and uniform cutting edge and discuss with them thepossibility of how it could have been made by deliberately knocking flakes off the sides using a hardstone a bit like a hammer.

In a letter written to the Museum, a visitor said: The opportunity to hold one of the oldest human

artefacts was a unique feeling, and I can honestly say that I have rarely found an object fit so neatlyinto my hand. It was the same for many of our visitors who handled the chopping tool.

It is one of the most memorable experiences of my time at the Museum.


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Professor Clive Gamble,

Archaeologist, Royal Holloway

University of London This stone tells two stories: one about the fossil ancestor who made the tool and the other about the fossil hunter who found it. Is it having

objects that makes us human?

The ancestor and the archaeologist are separated by almost two million years. They are similar because both walked upright and used tools.However, they differ greatly in the size of their brains and the sophistication of their technology. So are they both human?

Louis Leakey, the flamboyant Kenyan-born fossil hunter and champion of the importance of Africa for human evolution, was 28 when hefound this stone tool. Not everyone believed that they were ancient artefacts and he had to wait another thirty years before it could bescientifically proven.

At the time, he claimed that these ancient Olduvai people, for whom 28 was a ripe old age, were our ancestors because they had things, likethis tool. But crows, sea otters, monkeys and apes all make and use tools and we dont call them human. In fact, these ancest ors had brainsnot much larger than a chimpanzeealmost three times smaller than our own. So, if it wasnt big brains that made us tool users or tools alonethat made us human, was it our minds and imagination?

But how can a stone tool help us to understand the extent of the human mind? Certainly, it cannot tell us about a capacity for language or apassion of religious beliefs. However, the action of flaking the stone repeatedly to create a sharp-edged tool points to other imaginativepowers - appreciating the properties of materials, predicting the outcome of physical actions, and understanding that an alternative point ofview exists other than your own and acting accordingly. In other words our ancestors had an understanding of how other minds work,something no animal has and which children develop by the age of four.

To complete Leakeys tale, his discoveries were questioned and his long search for our African origins, as predicted by Darwi n, went on andon. His task was to convince others and eventually he triumphed. That was his story.

The toolmaker had other concerns to deal with. As this simple tool shows, he or she was just beginning to appreciate the potential of beinghuman, moving beyond the mental ability of apes and crows and into the foothills of the human imagination. Brains are needed to makeobjects. But two million years ago a new story began that married brains to objects in such a way that together the human mind evolved.

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