There are a number of different commercial print processes, all suitable for different applications. To find the best and most cost-effective process you'll need to know what

they are, how they work and what's the most appropriate for your job...

Design for print

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( 2 - 3 ) offset lithography

( 4 ) gravure

( 5 ) flexography

( 6 ) screenprint

( 7 ) pad printing

( 8 - 9 ) alternate / woodblock & digital printing

Design for print. offset lithography

dampening rollers

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Offset Lithography is the most popular printing method for small business marketing materials, and is often how most printed things you see have been produced.

In offset printing each colour of ink is applied separately, C-M-Y-K. One plate, One colour. Offset printing can also use premixed inks (SPOT COLOURS) to obtain hues outside the normal colour range of process printing.

Design for print. offset lithography

dampening rollers

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Offset Lithography is the most popular printing method for small business marketing materials, and is often how most printed things you see have been produced.

In offset printing each colour of ink is applied separately, C-M-Y-K. One plate, One colour. Offset printing can also use premixed inks (SPOT COLOURS) to obtain hues outside the normal colour range of process printing.

inking rollers

plate cylinder

offset cylinder

impression cylinder

stock

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Why would you use Offset Printing?

Low Price Per Piece - The more you print, the less you pay. This is because most of the cost is in the setup.Brilliant Quality - Producing rich, accurate colour and high-quality images and photographs, with sharp typefaces and fine details. HOWEVER the image quality is slightly inferior when compared to Rotogravure or Photogravure printing.

Types of Offset Lithography...

Sheet fed - Individual sheets >> Available in 'Full size' 28 x 40 inches/ 'Half size' or 'Quarter size'.

Web Offset - Fed from a large roll of paper, generally used for high volumes, examples include Catalogues and Maga-

How it works; Offset lithography works on a simple principle: Ink and Water don't mix! Image information is put on thin aluminium plates, in relief. The plate is securely clamped; a resilient rubber-coated cylinder, called the blanket cylinder; an impression cylinder; a system of inking rollers called the ink pyramid; and a plate dampening unit.

The litho plate is dampened, and then inked. Next, the inked image is trans-ferred (offset) to the blanket. The paper moves between the blanket and the impression cylinders, which are "packed" to ensure complete contact, and the image ink ink is transferred from the blanket on to the paper stock.

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Design for print. gravure

The biggest rival to web-offset is Gravure. This is an intaglio process that is used to print everything from the highest-quality postage stamps and banknotes, through glossy magazines and mail-order catalogs, down to rough-and-ready wallpapers.

How it works: Produced as a means of reproducing continuos tone. Present-day gravure machines are huge high-speed rotary presses that print from a web of paper. The engraved cylinder is partially immersed in a bath of thin, solvent-based ink. Its surface is flooded with ink, and as it revolves it is wiped clean with a flexible steel blade called a doctor blade, leaving ink only in the image areas.

A web of paper is pressed against the surface of the engraved cylinder by a rubber covered impression cylinder, and the ink is transferred to the paper. The paper passes to a folder and then a dryer, similar to those found on web-offset machines.

If your seeking to make an informed and responsible choice when it comes to selecting your stocks, look out for the 'Forest Stewardship Council Logo', A non-profit organisation looking for solutions to the problems created by bad forestry practices.

plate

plate cylinder

impression cylinder

ink

stock

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flexography

Flexography is a relief process, a form of letterpress, which prints using flexible rubber or photopolymer plates. Produced as a means of printing on non absorbent packaging materials. Flexography presses are rotary web-feed machines, similar in layout to gravure machines. Flexo generally uses thin inks, usually solvent-based and uses a two-roll inking system. A smooth metal founda-tion roll transfers the ink first to an etched metal or ceramic anilox roll, which is covered in dimples or cell of fixed size and depth (rather like a gravure cylinder) that act as ink-carrying reservoirs, and then to the printing plate or sleeve. Water-based inks containing fluorescent dyes can also be printed using flexography.

It is an economical process only for very large print runs, typically measured in millions of copies.

Because of the plate's squashiness, flexo is used for food packaging applications that require flexibility - printing on plastic bags and other non-absorbent stock such as cellophane and metal foil and corru-gated surfaces.

Flexography is often used for unglamor-ous applications, such as cardboard boxes and for difficult packaging materials such as waxed paper and plastic.

Advantages: Fast-make ready, prints well on non-absorbent stock, possibility of using water-based ink, prints well on cheap paper stock.

Disadvantages: Image spread, poor halftones, usually have to use solvent based ink, expensive to set up.

ink trough

impression roller

printing cylinder

anllox roller

fountain roller

rubber covering

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At the other end of the spectrum, the silkscreen process, or screenprinting is used only for relatively short print runs. It is a simple and direct method of delivering ink, and can thus be used to print on any kind of substrate, even on curved and uneven surfaces. It can produce thick and opaque deposits of ink, in brilliant, saturated colours.

The screen is made from synthetic gauzes or metal meshes. The screen has two functions: to support the stencil, and to regulate the ink. The screen itself is supported in a wooden or metal frame, evenly tensioned using air-powered or mechanical devices. Most screens are made from polyester. Screenprinting is mainly associated with poster and T-shirt printing.

Most screenprinting is very labor intensive, using a hand operated bench configuration - literally pulling the squeegee across the surface of the screen. The process can be automated on a rotary machine - the squeegee and flo-coater remain in the same position while the screen moves, paper is pulled by a gripper between the screen and a vacuum cylinder.

Advantages: Non-impact process, versatile.

Disadvantages: Small print runs, not recommended for halftones, close registration and four colour work is difficult.

Design for print. screenprint

a positive film is exposed and hardened onto a light sensitive emulsion applied to the screen

the emulsion attaches itself to the fabric mesh.

The desired ink is ‘squeezed’ through making your print

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At the other end of the spectrum, the silkscreen process, or screenprinting is used only for relatively short print runs. It is a simple and direct method of delivering ink, and can thus be used to print on any kind of substrate, even on curved and uneven surfaces. It can produce thick and opaque deposits of ink, in brilliant, saturated colours.

The screen is made from synthetic gauzes or metal meshes. The screen has two functions: to support the stencil, and to regulate the ink. The screen itself is supported in a wooden or metal frame, evenly tensioned using air-powered or mechanical devices. Most screens are made from polyester. Screenprinting is mainly associated with poster and T-shirt printing.

Most screenprinting is very labor intensive, using a hand operated bench configuration - literally pulling the squeegee across the surface of the screen. The process can be automated on a rotary machine - the squeegee and flo-coater remain in the same position while the screen moves, paper is pulled by a gripper between the screen and a vacuum cylinder.

Advantages: Non-impact process, versatile.

Disadvantages: Small print runs, not recommended for halftones, close registration and four colour work is difficult.

Design for print. screenprint

a positive film is exposed and hardened onto a light sensitive emulsion applied to the screen

the emulsion attaches itself to the fabric mesh.

The desired ink is ‘squeezed’ through making your print

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Pad printing utilises a flexible silicone rubber transfer pad that picks up a film of ink from a photo-etched printing plate and transfers it to a three-dimensional part surface. The unique properties of silicone rubber allow distortion-free, single or multi-colour images to be applied to flat, curved, or tapered surfaces with excellent definition and opacity. Pad printing inks, specifically formulated to adhere to various substrates, are used to decorate metals and ceramics as well as a wide range of of plastics.

Examples of pad printing

Medical devices (surgical instruments, etc.)

Implantable & in body medical items (catheter tubes, contact lenses, etc.)

Golf ball logos/graphics

Decorative designs/graphics appearing on Hot Wheels or Matchbox toy cars

Automotive parts (turn signal indicators, panel controls, etc.)

Letters on computer keyboards and calculator keys

TV and computer monitors

Identification labels and serial numbers for many applications.

pad printing

3/ pad deposits tacky ink onto the substrate

1/ solvents evaporate from the ink

2/ pad picks up tacky surface of ink

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Design for print. woodblock printing

Woodblock printing is a technique for printing text, images or patterns. The wood block is carefully prepared as a relief matrix, which means the areas to show ‘white’ are cut away with a knife, chisel, or sandpaper leaving the characters or image to show in ‘black’ at the original surface level.

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Design for print. woodblock printing

Woodblock printing is a technique for printing text, images or patterns. The wood block is carefully prepared as a relief matrix, which means the areas to show ‘white’ are cut away with a knife, chisel, or sandpaper leaving the characters or image to show in ‘black’ at the original surface level.

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Images are captured from a matrix of dots, generally called pixels. The digitized image is then used to digitally control the deposition of ink, toner or exposure to electromagnetic energy, such as light, to reproduce images. This allows colour management systems to help keep images looking the same colour despite where they're viewed or printed. This compressed data allows for the development of a common language for digital printing also know as 'PostScript' which has been developed by Adobe. To see what PostScript looks like you can open a PDF or EPS in a text editor, the code seems very intricate but to a computer it just a simple code of instructions.

One of the most important advantages of digital printing is that it offers a quicker response time due to its minimal press setup and it’s built in multicolour registration system. This eliminates many of the upfront, time consuming processes that can cause analog printing methods to have a slower turn-around time. Another advantage of Digital printing is the ability of offer variable printing

Digital printing technologies give the designer more options of substrates to print on due to its non-contact printing. This eliminates the distortion of images that occurs in analog process, like screen printing. It also requires less harsh methods of holding the substrate in the press, thereby giving more options of substrates. This means that substrates such as fabrics, very thin paper, and even ceramics can be safely printed on offering the customer more choices in designing.

digital printing

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