Textile Printing

Itistheprocessofapplyingcolourtofabricindefinitepatternsordesigns. In properly printed fabrics the color is bonded with the fiber, so as to resist washing and friction. Textile printing is related to dyeing but, whereas in dyeing properthe whole fabric is uniformly covered with one color, in printing one or more colors are applied to it in certain parts only, and in sharply defined patterns.The main objectives of textile printings are the production of attractive designs with well defined boundaries made by the artistic arrangement of a motif or motifs in one or more colors. Printed fabrics are well protected from friction and washing if dyes or pigments are applied properly on fiber. A strong bonding is formed between dyes and fibers.Steps in textile printing:Textile printing is carried out in different steps, such as: At first, fabrics should be pre-treated before printing. Printing paste must be prepared by using printing ingredients; printing performance depends on a well printing paste. Then, making an impression of the print paste on the fabric by using any of the printing methods, which is required. After that, drying is carried out on printed fabric. Steaming is carried out on printed fabric for fixing the printing paste on the fabric. At last, printing fabrics are neutralized by the after-treatment process.

History of Textile Printing:Early forms of textile printing are stencil work, highly developed by Japanese artists, and block printing. In the latter method a block of wood, copper, or other material bearing a design in intaglio with the dye paste applied to the surface is pressed on the fabric and struck with a mallet. A separate block is used for each color, and pitch pins at the corners guide the placing of the blocks to assure accurate repeating of the pattern. In cylinder or roller printing, developed c.1785, the fabric is carried on a rotating central cylinder and pressed by a series of rollers each bearing one color. The design is engraved on the copper rollers by hand or machine pressure or etched by pantograph or photoengraving methods; the color paste is applied to the rollers through feed rollers rotating in a color box, the color being scraped off the smooth portion of the rollers with knives.More recent printing processes include screen printing, a hand method especially suitable for large patterns with soft outlines, in which screens, one for each color, are placed on the fabric and the color paste pressed through by a wooden squeegee; spray printing, in which a spray gun forces the color through a screen; and electro coating, used to apply a patterned pile. Color may be applied by the various processes directly; by the discharge method, which uses chemicals to destroy a portion of a previously dyed ground; or by the resist, or reserve, method, which prevents the development of a subsequently applied color to a portion of the fabric treated with a chemical or with a mechanical resist.

Styles of Printing:A process for producing a pattern on yarns, warp, fabric, or carpet by any of a large number of printing methods. The color or other treating material, usually in the form of a paste,is deposited onto the fabric which is then usually treated with steam, heat, or chemicals forfixation.There are three different printing'styles' used to produce patterned effects on textiles, these being termed direct, discharge and resist. Each of these will be described in turn.

Direct Printing Style

This method involves the direct application of the color design to the fabric and is the most common method of textile printing. The dyes used for direct printing are those which would normally be used for a conventional dyeing of the fabric type concerned.

Discharge PrintingStyleIn this method the fabric is pre-dyed to a solid shade by a traditional dyeing process and the color is then destroyed locally, by chemicals incorporated in the print paste especially for that purpose. The result is a white patterned discharge on a colored ground.In white discharge printing, the fabric is piece dyed, then printed with a paste containing a chemical that reduces the dye and hence removes the color where the white designs are desired. In colored discharge printing, a color is added to the discharge paste in order to replace the discharged color with another shade.

Resist PrintingStyle

In this method of printing the fabric is first printed with a substance called a 'resist' which will prevent the dye from being taken up in a subsequent dyeing process. The resist functions by either mechanically preventing thedye from reaching local areas of the fabric or by chemically reacting with the dye or the fiber, to prevent adsorption.A printing method in which the design can be produced: (1) by applying a resist agent in the desired design, then dyeing the fabric, in which case, the design remains white although the rest of the fabric is dyed; or (2) by including a resist agent and a dye in the paste which is applied for the design, in which case, the color of the design is not affected by subsequent dyeing of the fabric background.

Methods of Printing:There are several methods of printing; the main methods are as follows:

BLOCK PRINTINGBlock printing is a printing technique for producing patterns by means of carving a design into a wooden block. The raised part is coated with ink and prints the design on fabric or paper which is similar to modern day stamping. It is the oldest form of printing known to man and has since been replaced by silk screening.Block Printing is one of the oldest types of printmaking, and has been around for thousands of years. There is evidence that it existed as early as the fifth century BC, with actual fragments found from as early as the fifteenth century. It has been done around the world, with roots in India, China and Japan.Since there is such a long history of block printing, there are many different techniques, but it is essentially using a carved material covered in ink to transfer an image on to paper or fabric. Block printing can be done with wood, linoleum, rubber, or many other materials, but we use linoleum for this work.Images that are printed with this technique are typically much bolder than other types of printmaking: since the blocks are carved by hand, there is often less detail and more texture to the prints. It is possible however, when using a very small knife, to carve blocks with a huge amount of detail.Block printing is also known as relief printing because the ink leaves a raised texture on the paper. This is different than letterpress where the image is applied with enough pressure to leave an indent on the paper; typically block printing is done by hand, so the ink sits on the surface adding a raised texture to the paper.

The Printing ProcessThe first step is to sketch the design. It is important to reverse the image if you are using text, as the printed image will be the reverse of what is on the block. Once you have the image ready, and then transfer the design on to the linoleum to give me an outline of where to carve.The next step is to carve the design. Carve away the parts that you dont want to print, as the ink will be applied to the raised surfaces to print the design. Whatever surface is untouched will be what prints onto the paper. Carving a block can take anywhere from an hour for a small piece, to several weeks or even months depending on the size and detail of the image.Use a range of knives, with very small-tipped knives for carving outlines and details, and much larger ones for cutting away the background. Carving the blocks takes a lot of patience, because if your hand slips it can ruin the whole piece. With practice, you can learn the amount of pressure it takes to carve the material, and the best techniques to use for certain designs.

Once the block is carved, trim the excess off with scissors to give it a straight edge, and then it is ready for printing. There are many different types of ink on the market, and its important to test them out to find the best one. Use oil-based inks because they give the best even coverage and print well on both fabric and paper, but there are lots of options out there.To print, squeeze a small amount of ink onto a piece of glass or Plexiglas, and roll it out with a roller (also called a brayer) to get a thin, even layer, because its important to apply the ink evenly to the block.Then roll the ink on to the block, making sure there is a thin but even layer on the whole design. Then take the block and press it down onto the paper or fabric. You can do this with your hands, a printing barren (a specific tool to apply pressure to a block), a rolling pin, by walking on it, or with a printing press whatever it takes to apply even pressure.The most important part is applying the pressure evenly, since the color will be stronger in some areas of the print than others if uneven pressure is applied. This is also a step that takes some practice and perfecting.The ink then takes several days to dry, so unlike other printing processes, there is a long wait time before the prints are ready to use. The oil based inks can take from two days to a week to fully dry, whereas water-based inks will dry slightly faster. The inks are made to dry slowly so that you are able to print without having the ink dry on the block; if you print with a fast-drying ink or paint, it will sometimes start to dry before you have even finished the print, giving a very uneven coverage.

Tips and AdviceBlock printing is very popular because of the bold and simple designs that can be created, but that simplicity takes a lot of steps to achieve. The technique is excellent for images with just a few colors and fewer details, but can be difficult to use for images with lots of small text, or very fine details that tend to break off the block with too many uses.One of the advantages of block printing is that it can be done on a surface of almost any size and texture like fabric, paper, canvas, wood and other materials, and you dont have to worry about fitting it through a printer or a press.Block printing is also an excellent way to produce a something that is truly handmade, but can be very easily replicated. Carving the block is time consuming and requires a lot of patience, but once you have the block you can use it hundreds or thousands of times.Block printing is also one of the easiest printing methods to get started with, since the materials needed to start are relatively inexpensive, and you dont need a lot of equipment for printing. Its a great way to get into printmaking!

SCREEN PRINTING:

Screen-printing is the most flexible printing process. It can be used to print on a wide variety of substrates, including paper, paperboard, plastics, glass, metals, fabrics, and many other materials including paper, plastics, glass, metals, nylon and cotton. Somecommonproductsfromthescreen-printingindustryincludeposters,labels,decals, signage, and all types of textiles and electronic circuit boards. The advantage of screen-printing over other print processes is that the press can print on substrates of any shape, thickness and size. An important characteristic of screen-printing is that a greater thickness of ink can be applied to the substrate as compared to the other printing techniques. This allows forvarious interesting effects that cannot be achieved through the other printing methods. Because of the simplicity of the application process, a wider range of inks and dyes are available for use in screen-printing than for use in any other printing process.

Overview of the Screen Printing Process Screen-printing consists of three elements The screen which is the image carrier The squeegee Ink

The screen-printing process uses a porous mesh stretched tightly over a frame made of wood or metal. Proper tension is essential to accurate color registration. The mesh is made of porous fabric or stainless steel mesh.

A stencil is produced on the screen either manually or photo chemically. The stencil defines the image to be printed in other printing technologies this would be referred to as the image plate.Screen printing ink is applied to the substrate by placing the screen over the material. Ink with a paint-like consistency is placed onto the top of the screen. Ink is then forced through the fine mesh openings using a squeegee that is drawn across the screen, applying pressure thereby forcing the ink through the open areas of the screen. Ink will pass through only in areas where no stencil is applied, thus forming an image on the printing substrate. The diameter of the threads and the thread count of the mesh will determine how much ink is deposited onto the substrates.

Many factors such as composition, size and form, angle, pressure and speed of the blade (squeegee) determine the quality of the impression made by the squeegee. At one time most blades were made from rubber, which, however, is prone to wear and edge nicks and has a tendency to warp and distort. While blades continue to be made from rubbers such as neoprene, most are now made from polyurethane, which can produce, as many as 25,000 impressions without significant degradation of the image.

Screen preparation:Screen (or image transfer) preparation includes a number of steps. First the customerprovides the screen printer with objects, photographs, text, ideas, or concepts of what they wish to have printed. The printer must then transfer a "picture" of the artwork to be printed into an image which can then be processed and eventually used to prepare the screen stencil. Once the artwork is transferred to a positive image that will be chemically processed onto the screen fabric (applying the emulsion or stencil) and eventually mounted onto screen frame that is then attached to the printing press and production begins.The silk screen is a wooden or aluminum frame with a fine nylon or silk mesh stretched over it. The mesh is coated with a light sensitive emulsion or film, which - when dry - will block the holes in the mesh. The image that needs to be printed is output to film eitherbycameraorimagesetter.Thisfilmpositiveandthemeshonthescreenaresandwiched together and exposed to ultraviolet light in a device called a print-down frame. The screen is then washed with a jet of water which washes away all the light sensitive emulsion that has not been hardened by the ultraviolet light. This leaves you with an open stencil which corresponds exactly to the image that was supplied on the film.Next the fabric to be printed is pinned on a wooden table so that it is evenly stretched and there are no ripples.Alternatively a wax table is used. The surface of the table is covered with wax. Below there are a network of pipes through which steam is passed. This causes the wax to soften and the fabric is just firmly pressed on to the table.Thewoodenframeofthescreenisfittedwithmetalhandleswhichwillfitontotocorrespondingwoodenprotrusions on the table. This is to aid placement, when two or more colors are being used. Thedye ispoured onthe screenArubber blade with awooden handle isfirmly pulled across the top of thescreen; it pushes the ink through the mesh onto thesurface of the fabric which is being printed. Another person stands at the other side of the table. He takes hold of the rubber blade and repeats the process. Since the nonprinting areas on the silk screen are blocked out, the ink is pushed through only the porous areas corresponding to the design and is thus transferred to the fabric. Ifmorecolorsareused,theprocessisrepeatedwithanotherscreenandcolor.Thescreen is always washed with a lot of water immediately after use. If this is not done, the dye dries on the screen and clogs up the design.

Flatbed Screen Printing

In flat bed screen printing, this process is an automated version of the older hand operated silk screen printing. For each color in the print design, a separate screen must be constructed or engraved. If the design has four colors, then four separate screens must be engraved. The modern flat-bed screen-printing machine consists of an in-feed device, a glue trough, a rotating continuous flat rubber blanket, flat-bed print table harnesses to lift and lower the flat screens, and a double-blade squeegee trough. The in-feed device allows for precise straight feeding of the textile fabric onto the rubber blanket. As the cloth is fed to the machine, it is lightly glued to the blanket to prevent any shifting of fabric or distortion during the printing process. The blanket carries the fabric under the screens, which are in the raised position. Once under the screens, the fabric stops, the screens are lowered, and an automatic squeegee trough moves across each screen, pushing print paste through the design or open areas of the screens. Remember, there is one screen for each color in the pattern. The screens are raised, the blanket precisely moves the fabric to the next color, and the process is repeated. Once each color has been applied, the fabric is removed from the blanket and then processed through the required fixation process. The rubber blanket is continuously washed, dried, and rotated back to the fabric in-feed area. The flat-bed screen process is a semi-continuous, start-stop operation. Flat screen machines are used today mostly in printing terry towels.

Advantages

large repeats

Multiple strokes for pile fabrics

Disadvantages

Slow

No continuous patterns

Productivity:

From a productivity standpoint, the process is slow with production speeds in the range of 15-25 yards per minute. Additionally, the method has obvious design limits. The design repeat size is limited to the width and length dimensions of the flat screen. Also, no continuous patterns such as linear stripes are possible with this method. However, this method offers a number of advantages. Very wide machines can be constructed to accommodate fabrics such as sheets, blankets, bedspreads, carpets, or upholstery. Also, this technique allows for multiple passes or strokes of the squeegee so that large amounts of print paste can be applied to penetrate pile fabrics such as blankets or towels. Currently, approximately 15-18% of printed fabric production worldwide is done on flat-bed screen machines.

Rotary printing:Rotary screen printing is so named because it uses a cylindrical screen that rotates in a fixed position rather than a flat screen that is raised and lowered over the same print location. Rotary presses place the squeegee within the screen. These machines are designed for roll-to-rollprinting on fabric ranging from narrow to wide-format textiles.

In rotary printing, the fabric travels at a consistent speed between the screen and a steel or rubber impression roller immediately below the screen. (The impression roller serves the same function as the press bed on a flatbed press.) As the fabric passes through the rotary unit, the screen spins at a rate that identically matches the speed of substrate movement.The squeegee on a rotary press is in a fixed position with its edge making contact with the inside surface of the screen precisely at the point where the screen, substrate, and impression roller come together . Ink is automatically fed into the center of the screen and collects in a wedge-shaped well formed by the leading side of the squeegee and the screens interior surface. The motion of the screen causes this bead of ink to roll, which forces ink into stencil openings, essentially flooding the screen without requiring a flood bar. The squeegee then shears the ink as the stencil and substrate come into contact, allowing the ink to transfer cleanly to the material.By converting the screen-printing process from semi-continuous to continuous, higher production speeds are obtained than in flat bed printing. Typical speeds are from 50-120 yards per minute for rotary screen printing depending upon design complexity and fabric construction. Rotary screen machines are more compact than flat screen machines for the same number of colors in the pattern. Therefore, they use less plant floor space.Also with rotary screens, the size of the design repeat is dependent upon the circumference of the screens. This was initially seen as a disadvantage, because the first rotary screens were small in diameter. However, with todays equipment, screens are available in a range of sizes and are no longer considered design limited. Todays rotary screen machines are highly productive, allow for the quick changeover of patterns, have few design limitations, and can be used for both continuous and discontinuous patterns.

Productivity:Estimates indicate that this technique controls approximately 65% of the printed fabric market worldwide. The principle disadvantage of rotary screen printing is the high fixed cost of the equipment. The machines are generally not profitable for short yardages of widely varying patterns, because of the clean-up and machine down time when changing patterns. Flat screen printing is much more suitable for high pile fabrics, because only one squeegee pass is available with rotary screen. However, rotary machines are used for carpet and other types of pile fabrics. Most knit fabric is printed by the rotary screen method, because it does not stress (pull or stretch) the fabric during the process.The rotarygarmentscreen printing machine, developed in the 1960s, is the most popular device for screen printing in the industry. Screen printing on garments currently accounts for over half of the screen printing activity in the United States.

Advantages Fast Quick change over of pattern Continuous patternDisadvantages Design limitations Small repeats

Transfer Printing:Transfer printing is the process of putting images onto a special paper and then using that printed paper to transfer the images to your fabric with a hot iron or hot press. Heat transfer is great for producing clear and very well defined images.

Supplies Plain cotton T-shirt. T-shirt transfer paper. Some cool graphics. (You can use whatever you like here.) A printer (ink jet not laser jet). An iron, with the steam setting switched off. A hard surface, with a couple of tea towels on top. Note:notan ironing board as this is too soft for the transfer to take properly.

Once youve gathered all your supplies, its really very simple to transfer the print onto the T-shirt. The instructions that follow work with the transfer paper , but obviously check the instructions on your paper before you go ahead.

Process

1. Practice printing your graphic out onto normal printer paper first. You want to make sure you know which side of the paper your printer is using, that the graphic is the right size for your T-shirt and that it looks how youd like it to once its printed out. Put the white paper over the T-shirt and make sure it all looks right. Its also worth pointing out that your final graphic will appear as a mirror image of the one in front of you, so make sure it looks okay this way round. (If youve got words in your image, you can use the mirror setting on your printer, though this might not give as clean a print as normal.) But at this stage, experiment and make sure youre completely happy with your results before you put it onto the transfer paper.2. Print!3. Cut round the details of the graphic as closely as you can. Try and remove as much of the area that has nothing on as possible.4. Line up your image onto the T-shirt. The clear side with the print on should face the fabric, the white side with the squares faces out. Check and check again that its straight and just as you want it to be.5. Iron the paper for around two minutes. Make sure the steam setting is not switched on. Concentrate on the centre first and then work your way out to the sides.6. Let the paper cool down.7. Carefully and slowly remove the white backing, starting at one of the edges and pulling it off evenly.8. Admire your creation

From a distance, and away from direct light, the T-shirts look great. Every little detail of the pattern has been transferred, crisp and clear onto the T-shirt fronts.But up close, or in the light, the area where the transfer has been ironed is really shiny and stiff, to the point of being reflective. That area has also lost any stretch, so it sits stiff and solid even when its being worn. Overall, it definitely looks amateur.Because we used an image that has lots of black lines with white space behind it, those areas which should appear neutral show up shiny. This method would work far better for transferring on a solid block image, probably with color, rather than one that any blank spaces in. Then, youd need to cut exactly round the image you had and youd eliminate this problem of shiny areas where nothing is happening.You will reassess once theyve been through the wash a few times, as that might help soften it up a bit, try to use solid image to prevent from this problem.

Advantages High quality print Fewer seconds Economical for short runs Pollution free

Disadvantages: Slow process Primarily for polyester

Other Methods Of Printing:Stencil PrintingThe design is first cut in cardboard, wood or metal. The stencils may have fine delicate designs or large spaces through which color is applied on the fabric. Its use is limited due to high costs involved..

Blotch PrintingIt is a direct printing technique where the background color and the design are both printed onto a white fabric usually in a one operation. Any of the methods like block, roller or screen may be used..

Airbrush (Spray) PaintingDesigns may be hand painted on fabric or the dye may be applied with a mechanized airbrush which blows or sprays color on the fabric.

Electrostatic PrintingA dye- resin mixture is spread on a screen bearing the design and the fabric is passed into an electrostatic field under the screen. The dye-resin mixture is pulled by the electrostatic field through the pattern area onto the fabric.

Photo PrintingThe fabric is coated with a chemical that is sensitive to light and then any photograph may be printed on it.

Differential PrintingItisatechniqueofprintingtuftedmaterialmadeofyarnshavingdifferentdyeingproperties such as carpets. Up to a ten color effect is possible by careful selection ofyarns, dyestuffs and pattern.

Warp PrintingIt is roller printing applied to warp yarns before they are woven into fabric.

Tie DyeingFirm knots are tied in the cloth before it is immersed in a dye. The outside of the immersed portion is dyed but the inside is not penetrated. There are various forms of Tie-dyeing like Ikat Dyeing where bundles of warp and/ or weft yarns are tie dyed prior to their weaving. In Plunge Dyeing the gathered, folded or rolled fabric is usually held with stitching to form specific patterns.

Batik DyeingIt is a resist dyeing process. Designs are made with wax on a fabric which is then immersed in a dye. The unwaxed portion absorbs the color.

Jet Spray PrintingDesignsareimpartedtofabricsbysprayingcolorsinacontrolledmannerthrough nozzles.

Digital printingIn this form of printing micro-sized droplets of dye are placed onto the fabric through aninkjetprinthead.Theprintsystemsoftwareinterpretsthedatasuppliedbyacademic_Textiledigitalimagefile.The digital imagefile hasthe datatocontrol the droplet output so that the image quality and color control may be achieved. This is the latest development in textile printing and is expanding very fast.

Conclusion:

At the initial stage of printing, the printing work was done by hand but day by day this style is changing by utilizing different modern techniques. Now different types of critical printing is done very easily by the bless of modern science. Most of the printing machines are controlled by the computer. Graphic design is mostly use in printing process. Different types of textile machine manufacturing companies trying to improve the present techniques of printing methods.Anyhow, printing process plays an important role in the civilized world. Multiple colors can be use in printing process. Sometimes printing properties show the identity of a nation. So, we should give great emphasis on printing process to produce different types of attractive designs on textile material.

BIBLIOGRAPHY

file:///D:/report/Block%20Printing%20Basics%20-%20TopTenREVIEWS.htm file:///D:/report/The%20Printing%20Process%20%20Block%20Printing%20%20%20Oh%20So%20Beautiful%20Paper.htm file:///D:/report/textiles%20%20The%20Printing%20of%20Textiles%20%20%20Infoplease.com.htm file:///D:/report/Technological%20Advances%20in%20Rotary%20and%20Flatbed%20Printing.htm file:///D:/report/Heat%20Transfer%20Printing%20-%20Wisconsin%20Screen%20Process.htm file:///D:/report/Different%20types%20of%20textile%20printing%20processes.htm file:///D:/report/Textile%20Printing%20%20%20Definition-Styles%20and%20Methods%20of%20Printing%20%20%20Textile%20Fashion%20Study.htm file:///D:/report/How%20does%20the%20heat%20transfer%20process%20work%20%20-%20Local%20Hero.htm

20 | Page