ALL-OVER PRINTING (AOP)
The garment industry of Bangladesh started in 1978 with the Riaz store. All-Over Printing had started in the Bangladesh garment industry in the 1980s. In the early days of the garment manufacturing industry, very few factories worked in All Over Printing (AOP). In time, printed fabrics were made only for the local market, not for the world market.
From 1980s, AOP started its excellent journey in export oriental factory within the Bangladesh. Now, AOP are running about 85+ factories in Bangladesh. Bangladesh has already gained the skill to compete with any country within the world with AOP and has created a powerful position. The tastes of the buyers in the current fashion world are changing day by day and the demand for All Over Printing (AOP) is increasing day by day keeping pace with the tastes of the buyers.
Now let us know the detailed information about All Over Printing (AOP).
What is All Over Printing?
All over printing, AOP is a term used to describe a special kind of printing that covers and repeated across the whole surface of apparel. Besides, AOP is basically a special type of textile printing technology, where printing is done across the full width of the fabric.
THREE TYPES MACHINE ARE USED IN AOP TECHNOLOGY:
- Rotary screen machine.
- Flatbed screen machine.
- Digital printing machine.
Rotary screen and flatbed screen machines are very common in our textile industry. Digital printing machines are not yet so available in our Industry. But soon digital printing machines will take the place of Rotary and Flatbed machines.
ROTARY SCREEN PRINTING MACHINE:
Features of rotary screen printing machine are point out below:
- The screen of rotary screen-printing machine is Round and the screens are made of Nickel.
- During developing the planning for the rotary screen, the developer creates a repeat of the planning by calculating the diameter of the screen. The diameter of the Rotary screen is 641 mm, 820mm, 914mm and 1018mm.
- The amount of color print capacity of the rotary screen is 20 colors. But because of the complexity of Machine Setting, usually, printing is done no more than using 12 colors. For example, if the fabric has 10 colors, then use 10 screen.
- The Fabric printing rate per minute is 30-60 meters. Fabrics print faster when the design contains a lower number color.
- Colors automatically passing to the rotary screen from the drum with the help of a machine compressor and color wastage is higher in rotary screen printing.
- Cost of the Rotary screen is high. Per Screen, the cost is approximately 5k-8k TK in BDT. It depends on the diameter of the rotary screen.
- Rotary screen does not have the Possibility to shows Repeat mark or Join mark during Print.
- The more the color of the design, the fabric wastage is more during setting the design in fabric printing.
- All kinds of the design can’t be printed on a rotary screen-printing machine.
- Any types of fabric can be printed.
- There is a possibility to break the screen while the machine running.
- For color penetration, various sizes of stainless steel rollers or blade squeegee are used inside the screen.
- Due to the machine runs very fast, screen rotation is also fast. So, after printing done certain times some pinholes come out on the screen, for this reason, remove the screen from the machine and to remove the pinhole by re-touching is required. Then the machine starts again for further production.
- Screen preparation process is complicated. It takes more time to expose and develop the screen. Approximately every screen takes 25 to 35 minutes to expose.
- After developing the screen and before setting on the rotary machine need to harden the coating chemical of the screen, for that each screen curing is done by setting on the polymerize machine for 20 to 30 minutes.
- Need to coating, the screen by using Photo Emulsion RS-100 and RS-1203 before exposing the screen. To coating, each screen has required approximately 200 grams of Chemical.
- CMYK’s design can’t be print perfectly on a Rotary screen-printing machine.
- Rotary screen-printing m/c is unprofitable for short quantity production.
- The initial installation cost of the Rotary screen-printing machine is very high. So, this is expensive.
- Disperse or Reverse printing is goodly done on a Rotary screen-printing machine.
- Color separation can be done within a short time.
- Critical design in laser exposing machine such as 1-pixel line, 1-pixel dot, or spray, the screen does not open perfectly on the screen. As a result, sometimes the development screen design doesn’t fully match the main design/ buyer design.
- If the fabric is printed in the rotary screen-printing machine, there is a possibility of failure in the heavy metal (Nickel) test of the fabric.
- Rotary screen-printing machine has a limitation of squeegee pressure.
- After production, the screen must wash perfectly with water, either, the open area of the screen becomes blocked and Production can’t be done next time.
- A screen can be reused 3/4 times.
- The resolution should be 360, 508, 720 pixels/inch in developing a design. The higher the resolution, the higher the time it will take in screen preparation.
- In AOP, color is created by matching the shade with the pantone (TCX, TPX) or color swatches and then printing is done.
- The production can be done at any temperature and humidity of the floor.
- This printing is possible on deep-dyed fabrics or black fabrics. And also White print can be done on any type of fabric.
Many types of machinery are used to expose the rotary screen:
- Exposing machine-Inkjet or Laser
- Cool dryer machine/Climatizer
- Coating machine.
- Polymerize machine.
- Light stand and developing stand.
- Water tank/ Screen developing tank.
- Endring fixer/Endring gluing machine.
- Unpacking Machine.
- Screen checking stand.
Here some machines name are list out with their origin:
- Ji- long………China
The steps of rotary screen preparation are given below:
1) Screen rounding and degrease:
The new screen is removed from the packet and also the tension ring is carefully attached to each side of the screen, which may be easily removed from the screen or reconnected. After attaching tension ring the screen needs to be kept within the polymer machine at a temperature of 160 degrees for 40-60 minutes. The quantity of grease applied to the screen hardens the screen because of the grease hit and rounds the diameter of the screen perfectly. And this process is named screen rounding.
After rounding the screen, the screen got to be degreaser. A degreaser may be a kind of soapy water that’s ready to clean the grease or oily substance on the screen. The screen is degreased with foam by mixing one a part of water with four parts degreaser and inserting the screen inside the developing stand.
Or after soaking the screen during a degreaser tank for 15/20 minutes and washing it with water, it becomes a screen degreaser. After rounding the screen, you’ve got to insert the screen inside the lighting stand and check it well by turning on the light. Whether the mesh hole is closed or if there’s any dirt on the screen, if any hole is closed or dust is on the screen, it should be cleaned with compressor or water pistol machine. Then the screen is polymerized at the temperature of 40-120 C for 20/30 minutes or at normal humidity with water for 4/6 hours to realize an appropriate form for coating.
2) Screen coating:
The screen is to be coated during a light yellow room. Excessive light dissipates the warmth of the emulsion. To stay the temperature of the emulsion perfect, AC should be installed within the screen preparation room, if the emulsion contains any tiny sand particles or the other dirt, during screen coating, those sand particles will form a pinhole on the screen.
There are generally three kinds of chemicals utilized in screen coating:
- Universal emulsion
- Sensilax sensitizer
200 grams of chemicals are wont to make a screen coating. In 100 g of emulsion, 10% water, 5% sensitizer and also the rest are photo emulsions.
Many times the share of chemicals has got to be changed counting on the thickness & sharpness of the design. During this case 20% water has got to be used and at an equivalent time an exposer uses his practical experience to try to this. Many new chemical companies are currently marketing readmit emulsions. It’s usually wont to make emulsions in step with design variations.
For best results, mixing emulsion should be mixed all right by stirring with a stick.
Screen coating is finished in two ways:
- Coating machine
- Manual process
a. Coating machine: 200gm of the prepared emulsion is added into a clean scraper ring and coated on the clean screen with a speed at 10-12 min. Then dried at 35oC – 40oC and 60% ratio in an oven with circle wind and on over ± 20c temperature differences. Coat the binder evenly on the both surfaces beaten the enduring and also the nicked screen with a scraper coup ting and removing the excessive binder.
b. Manual system: Manually coating the screen doesn’t make the emulation penetration 100% perfect on the screen, resulting in various problems, but not such a lot the matter with the local design. Moreover, within the case of export design, this manual system isn’t acceptable, also as manually screen coating isn’t perfect and time is wasted, for this reason, screen coating is not any longer done manually. Exposers often solve many screen problems by reducing or increasing the viscosity of the emulsion, for instance, making emulsions counting on the exposure or sharpness of the planning. After coating the screen, the screen has got to be kept upright for 15/20 minutes so the emulsion applied on the screen comes down by rolling. Then the screen should be kept within the emulsion machine at the temperature of 30/35 degrees Celsius for 20/25 minutes. This dries the emulsion applied to the screen. If there’s no clematises machine, it are often dried during a light-dark room with normal fan air, during this case, it takes longer, about 2/3 hours. If the emulsion screen isn’t exposed within 4/5 hours, the emulsion temperature is lost. However, in a very dark room with AC, the coated screen is often finished up to 18 hours.
3) Screen expose:
After the screen coating, the screen has to be exposed. The device by which the screen is exposed is called the rotary screen exposing machine.
There are also three types of exposing machines:
- Manual exposing machine.
- Inkjet exposing machine.
- Leaser exposing machine.
When designers did manual design, they used to expose it in manual exposing machine. There were various problems in manual expose but even after that manual expose was given, the main material for giving manual expose is design film. With this film, part by part exposure was given and the cost would be less.
With the change of technology, CAD exposing process started instead of manual. First Inkjet then Leaser exposing system is started. Any critical design can be perfectly exposed in inkjet and laser exposing machine.
4) Screen developing wash:
After exposing the screen, the screen has to be developed within 10/15 minutes. If wait for a long time, the emulsion of the screen becomes hard, so there is a problem in screen wash.
The exposing screen has to be carefully immersed in water in the developing tank. Make sure that the screen does not rub against the body of the developing tank. Because if the tank is rubbed hard, the screen emulsion is likely to go up. Under of the develop tank has two semicircular stands, above which, carefully soak screen on it in water for 10/15 minutes. The screen should be removed from the develop tank and the outside and inside of the screen should be cleaned with water under high pressure through a shower. And sometimes, rub lightly with foam. In this way the design area is opened from the screen at water pressure.
Then insert the screen inside the lighting stand and check each motif of the design. If a motif is not fully open, it must be opened with the help of water gun machine. At this time, it is very carefully noted that, the extra area of the design is not opened. Thus the exposing screen has to be developed by the water very carefully.
After that it is necessary to remove the water from the screen, for this removing the screen from the light stand and keep it upright for 10/15 minutes. Then the emulsion on the screen surface should be kept inside polymerize at the temperature of 120 degree Celsius for 20 minutes to harden it.
5) End ring gluing:
To remove the screen from polymerize, end ring gluing is done. And before doing the end ring gluing should be cleaned well.
After that the end ring adhesive should be applied manually on both sides of the end ring (front side and back side) of the screen. After applying the adhesive, the adhesive should be dried for 10/15 minutes.
Then with the help of end ring gluing machine, put the end ring inside the screen and hit for 10 minutes. After hitting the end ring will be firmly attached to the screen. If the end ring does not attach perfectly, then the screen will be destroyed by opening the end ring during fabric production. For this, the end ring should be applied very carefully.
After inserting the end ring, the screen has to be checked by inserting it in the check stand. If a pinhole or extra area of the design area is opened on a screen, it should be closed with a brush with photo emulsion.
How to Find Out the Mistakes of Rotary Screen?
If after the completion of the printing process it is seen that the design as asked by the buyer has not been done properly. The line of such a design may have become one millimeter instead of a half millimeter. Then you have to check the design, mash selection, pressure, speed, viscosity to find out exactly where the problem is.
It will not be possible to find out just by looking at such a mash selection in one place. You have to check all the steps starting from the design.
The following are all the important steps to be discussed:
The design is developed by the designer through a series of processes in the same way that the buyer is asked to design for printing. Design is the most important step of printing, because the subsequent activities are completed according to the design. That is why design is called the heart of printing. So we have to keep an eye on the design so that it is not wrong. Designers need to have a clear idea about textile printing design.
Mash means the hole in the screen. If the mash is less, the hole in the screen will be bigger. If the mash is more, the hole in the screen will be smaller. Depending on the mash selection, the thickness of the printing line will be thicker or thinner.
If the line is half a millimeter, the mash can be 155. If the line is one millimeter, the mash can be 70. If 60 mash is given in place of 155 mash, then half millimeter will be one millimeter in place of line. It will not match the design given by the buyer.
So you have to do the mash selection properly to do the design properly.
The color will come out of the screen, it depends on the pressure. If you put more pressure, the color will spread more. If you put less pressure, the color will be less.
If the speed is high, the production will be high. If the speed is low, the production will be low.
Now the question is, when will the speed be higher? When will it be lower?
If the number of colors of the fabric is less, the speed of the machine will be higher, and then the production will be higher. If the number of colors of the fabric is more, the speed of the machine will be less, and then the production will be less.
Viscosity means density. If the color density is low, the liquidity is high. If the density is high, the liquidity is low.
If the density is less than required, the printing paste should be spread on the fabric. So the viscosity of the color should be as much as it needs to be.
FLATBED SCREEN PRINTING MACHINE:
Features of flatbed screen printing machine are point out below:
- The screen of the Flatbed screen printing machine is flat. Screen is made of polyester or bolting cloth which is attached to the aluminum frame with 100% tension.
- Any kind of design measurement can be developed in a flatbed screen. For those different sizes of screens are used.
- Flatbed screen printing can print more than 12 colors.
- The fabric print rate per minute is 15-20 yards.
- Color is given manually on the flatbed screen during printing. Here, color wastage is lower.
- The cost of a flatbed per screen is approximately 3k-4k TK in BDT.
- During printing if the print was 100% body coverage design then the Repeat mark or Join mark will show.
- Smoothness and sharpness of the design in flatbed screen printing machine is relatively good.
- The fabric wastage is lower during setting the design in fabric printing.
- Flatbed screen printing machine can be print any kind of design. Such as – Sari, Three pieces, Bed Sheet, Then Cloth, etc.
- Any types of fabric can be printed. But, in knit fabric the sharpness and print quality is good.
- There is no possibility to break the screen while the machine running.
- Fabric print is done automatically by pressurizing of rubber Squeegee on the frame.
- Fabric print is done by ups and downs of the flatbed screen and fabric is printed slowly. So the possibility of coming out Pinholes on the screen is lower than the rotary screen machine.
- Screen preparation process is easier. Approximately every screen takes 20 to 40 minutes to expose.
- After developing the screen and before setting on the flatbed machine coating chemicals are harden by using the hardener chemical.
- Need to coat the screen by using Photo Emulsion SP-1300-HV and TXR before exposing the screen. To coating, each screen has required approximately 200 grams of Chemical.
- CMYK’s design can be print perfectly on a flatbed screen printing machine.
- Flatbed machine printing m/c is profitable for short quantity production.
- The initial installation cost of the flatbed screen printing machine is low. So, this is inexpensive.
- Vertical stripe easily can’t be print by flatbed screen printing machine because the join mark or repeat mark is shown.
- Disperse or reverse printing is not goodly done on flatbed screen printing machine.
- In Laser exposing machine, critical design such as 1-pixel line, 1-pixel dot, or spray, open perfectly on the screen. As a result, after developing the screen, the type of line or dot in the design are fully matched to the buyer design.
- If fabric print on a flatbed screen printing m/c, there is no possibility to present metal (nickel) in fabric. So, surely the Nickel test will be passed.
- There are no limitations of squeegee pressure in flatbed screen printing m/c.
- After production, the screen needs to wash perfectly with water. Either, the open area of the screen becomes blocked and production can’t be done next time.
- A screen can be reused 3/4 times.
Here some flatbed screen printing machines name are list out with their origin:
- KUIL………….South Korea
- STORK ……….Netherlands
- ZIMMER……. Austria
Types of All-Over Printing Paste: (Rotary & flatbed):
There are six kinds of all over printing paste these are:
- Pigment Print
- Reactive Print
- Discharge Print
- Raised Print
- Glitter Print
- Burnout Print
In rotary screen printing the reactive print is the lightest and the discharge print is the hardest. Reactive printing cannot be done on dyeing or on black fabric. Discharge is printed on deep dyeing.
In flatbed screen printing (Discharge, Glitter, White paste and apson) print Smoothness and Sharpness shows relatively good then the Rotary screen.
LIMITATION OF AOP IN ROTARY AND FLATBED SCREEN:
There are some limitations in AOP. The main limitation is:
- We cannot print any design on rotary screen or flatbed screen.
- No more than 20 colors can be used in rotary and flatbed screen.
- The print cost is higher
- Complexity of machine. The effect of photo print and 3D cannot be brought clearly through AOP.
Bangladesh’s garment sector is dependent on buyers’ requirements. When a buyers’ submits a design, then how do you know if it is possible to print this design or not?
10 Important Things for All Over Printing:
When receiving designs from buyers, a clear understanding of those below 10 things are crucial. If one is missing, then it creates a problem.
- If there is no repeat.
- If there is no design repeat measurement.
- If there is no clear design file or image.
- If there is no print paste-type.
- lf there is no fabrication.
- If there is no number of print color.
- If there is no reference of base/ground dyeing color.
- If there is no fabric GSM and fabric diameter.
- If there are no Panton or color swatches.
- If there is no mention the category of sample.
ALL OVER DIGITAL PRINTING:
Due to some different challenges, rotary and flatbed screen are added to the new technology ‘All Over Digital Printing’. Currently, 60% of digital print is completed in Bangladesh, India, Indonesia, Pakistan and Vietnam. Due to increasing demand, many Bangladeshi printing factories have started digital printing. Digital print is directly printed in fabric with ink. No film or screen is employed for this. A perfect technology for multi-dimensional design printing is ‘All Over Digital Printing’.
DIGITAL PRINTING MACHINE:
Features of digital printing machine are point out below:
- Screen is not required in this printing.
- Digital design development process is different as:
- Most of the designs are done by Photoshop software. Sometimes Adobe Illustrator software is also used.
- Color separation doesn’t require. The work has to be done on the main image or the file of the design.
- The brightness of the design file has to increase or decrease to match the color of the main sample. Example: The color contrast-which is used for woven fabrics-is not the same for the knitted fabrics. Another type of color contrast is used for knitted fabric.
- Decision has to be made depending on the texture of the design that which mode should be used in developing design RGB mode or CMYK mode.
- Most of the designs are used 8 inks in the printing on fabrics. They are: A) Cyan B) Magenta C) Red D) Yellow E) Black F) Orange G) Blue H) Grey
- All types of fabric can be print except blended fabric like PC, CVC, etc.
- The quality of digital printing on deep-colored fabrics is not good enough.
- White color print is not possible.
- Reactive, Acid, Disperse and pigment can be done by digital printing.
- RGB and CMYK both modes are possible in this printing to develop a design. To get a better quality of printing on fabrics, the file of the design printing needs to be cleared.
- The resolution has to 300-1200 pixel / inch when developing the design. Depending on the quality of the printing, the resolution is selected. The higher the resolution, it takes higher time in developing design, the production is slowed down and a better quality of printing is achieved.
- The production rate is lower. The production depends on the machine head. The higher the number of heads, the higher the production. Generally, the production rate is (1-3) m/min. The production rate of MS Lario machine is around140 m/min. Only Robin Tex has the machine.
- The printing has to do in the AC room. Temperature 25°C and Relative Humidity (RH) 65%±2% required. Otherwise, it will effect on print heads and color continuity.
- Before printing, fabric requires the pre-treatment process. But, needs less chemical than traditional printing for coating. Thickener, Urea, Sodium Bicarbonate and water are needed for coating. Sometimes resist salts are also used depending on types of thickener.
- Uses of water is 90% less and electricity is 30% less.
- No limitation of color. As a result, better sharpness can be attained.
- Need steaming after printing. Fixation is done in steaming.
Continuous process flow chart for all-over digital printing:
Here some machine name are list out with their origin:
- Reggiani Machine (Italy brand)
- Durst (Italy brand)
- MS Machine (Italy brand)
- Atexco (China)
- Homer digital print (China)
Here is a List of All-Over Printing Factories in Bangladesh:
- Unifill Composite Dyeing Mills Ltd.
- SIM Group.
- HH Textile Mills Ltd.
- Sanjana Fabrics Ltd.
- Beximco Textile Division.
- Rahim Textile Mills Ltd.
- Divine Group.
- Thermax Group Ltd.
- Hossain Dyeing & Printing Mills.
- Tania Textiles Ltd.
- GMS Composite Knitting Industries Ltd.
- Pakiza Knit Composite Ltd.
- Knit Concern Group.
- Unicon Group
- DBL Group.
- NR Group.
- Robintex Group.
- Chaity Group.
- APS Group.
- Comfit Composite Knit Ltd.
- South China Bleaching & Dyeing Factory Ltd.
- Mithela Textile Industries Ltd.
- Knitwear Ltd.
- Monno Fabrics Ltd.
- Rim Dyeing Ltd.
- K.N Textile Ltd.
- Apex Holdings Ltd.
- Four H Group.
- Utah Group.
- Dird Composite Textiles Ltd.
- Palmal Group of Industries.
- Mosharaf Composite Textile Mills Ltd.
- KDS Group.
- Opex & Sinha Textile Group.
- Impress-Newtex Composite Ltd.
- Tru Fabric Limited,
- Zaber&Zubair Fabrics Ltd.
- Chorka Textile Ltd.
- Jamuna Group.
- Satter Textile Mills Ltd.
- Dyeing, Printing & Finishing Ltd.
- Amanat Shah Fabrics Ltd.
- Sawfttex Ltd.
- Pride Group.
- NZ Group.
- Intramex Textile Ltd.
- RK Group.
- NZ Group.
- Metro Knitting and Dyeing Limited.
- ACS Textiles (Bangladesh) Limited.
- A Concern of Micro Fibre Group.
- A-One Polar Ltd.
- Lithe Group.
- AJI Group.
- Mondal Group.
- Phonex Textile Ltd.
- All Tex Group.
- Infinia Group,
- Silver Composite Textile Mills Ltd (Unit-3, Textile)
- Croni Group.
- Azad Rifat Fibers Ltd
- Bornali Fabric.
- Bomby Fabric.
- S B Style Composite Ltd.
- Padma Bleaching & Dyeing Mills Ltd.
- Experience Textile Ltd.
- Tithi Textile Mills Pvt Ltd.
- Antim Group.
- Consumer Textile Mills Ltd.
- Fariha Knit Tex Ltd.
- PN Composite Ltd.
- Nice Fabrics Processing Limited.
- Unity Fabric Ltd.
- Primer Dyeing & Printing Mills Ltd.
- Bengal Apparel Ltd.
- Urmi Knitwear Ltd.
- Noor Group.
- Regent Textile Ltd.
- Younusco Group.
- Paramount Textile Ltd.
Here is a List of the Factories in Bangladesh that have Digital All-Over Printing Machines:
- Dird Composite Textile Ltd.
- Naz Bangladesh Ltd.
- Silver Line Composite Textile Ltd.
- Hossain Dyeing & Printing Limited.
- Nice Fabrics Processing Limited.
- ACS Textiles (Bangladesh) Limited.
- Jamuna Group.
- Pran RFL Chorka Textile.
- Beximco Textile Division.
- Mondol Group.
- GMS Composite Knitting Industry Limited.
- Robintex Group.
- Echotex Textile Ltd.
- Apex Holding Limited.
- Knit Concern Group.
- Experience Textile Ltd.
- Hr Textile Mills Limited.
- UTAH Group.
Special thanks to Md Shawkat Hossain (Sohel) sir, to take session with so much sincerity.
Author of this Article:
Jannatul Ferdous Meem
Textile Engineering College, Noakhali
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It’s me, a Textile Consultant, Blogger & Entrepreneur. I’m working as a textile consultant in several local and international companies. I’m also a contributor of Wikipedia.