Design for Print// Commercial Print Process

CMYK: Stands for "Cyan Magenta Yellow Black." These are the four basic colors used for printing color images. Unlike RGB(red, green, blue), which is used for creating images on your computer screen, CMYK colors are "subtractive." This means the colors get darker as you blend them together. Since RGB colors are used for light, not pigments, the colors grow brighter as you blend them or increase their intensity.

SPOT COLOUR: Print technicians and Graphic Designers around the world use the term spot colour to mean any colour generated by a non-standard offset ink; such as metallic, fluorescent, spot varnish, or custom hand-mixed inks. (as opposed to obtaining a colour by via mix of cmyk)

GREYSCALE: One colour black and all the shades of grey through to white (black and white photography is grey scale)

MONOCHROME (mono): Monochromatic colours are all the colours of a single hue derived from one colour and extended using the shades,tones and tints of that colour.

HALFTONE: This is a mechanical process (as opposed to chemical) for converting tonal values into a series of dots thatalthough solid dots, when printed give the impression of continuous tone.

STOCK: Generally stock can be divided down into 3 catagories- Paper, Paperboard or Card Board - as well as 3 finishes - Matt, Satin, Glossy

STOCK WEIGHT: Refers to the the thickness or density of the chosen Paper or Board. Paper products that let little or no light pass through (e.g. poster board) are considered dense or heavy. Paper products that allow some light to pass through (e.g. tissue paper) are considered lightweight. 

Flexography

Flexography is a method of direct rotary printing that uses resilient relief image plates of rubber or photopolymer material.  The plates are affixable to plate cylinders of various repeat lengths, inked by a cell-structured ink-metering roll, with or without a reverse-angle doctor blade, and carrying a fast drying fluid ink to plates that print onto virtually any substrate, absorbent or nonabsorbent.  Flexography is a rotary printing method which means for every revolution of the printing plate cylinder, an image is produced.

Best of all, at Dac Labels & Graphic Specialties, Inc. we are able to achieve a level of print quality that rivals even high quality sheet fed printing.

• It can print on a wide variety of absorbent and nonabsorbent substrates.
• It uses fast-drying inks, whether solvent, water-base or ultraviolet (UV) curable.
• It can print wet ink over dry ink to eliminate trapping problems, back-trap contamination and setoff.
• It uses resilient rubber or photopolymer image carriers that can print millions of impressions.
• Presses can accommodate a wide range of cylinder repeat lengths to match customer printlength requirements.  Flexography is a near total variable-repeat-length system.
• Its inking system can deliver a predetermined amount of ink with minimum on-press adjustments.
• It can print continuous patterns (gift wrap, wallpaper, floor tiles).
• It can print on extensible plastic films.
• It can print on the reverse side of stretchable, transparent films.
• It can perform coating and in-line laminating operations.
• It is cost effective for many applications.
• It enables fast turnaround time between jobs.
• It can do short-run work profitably.
• Presses can produce in-line, pressure sensitive labels in a continuous operation.
• Presses can produce many types of projects requiring down line finishing such as:  diecutting, kiss cutting, scoring, perforating, embossing, hole punching, etc.

Clemson University Graphic Communications Students documented the entire process from product development to finishing. This project was done for the 2012 Annual Phoenix Challenge

Digital Printing 


Digital Printing takes a different approach assembling each image from a complex set numbers and mathematical formulas. These images are captured from a matrix of dots, generally called pixels, this process is called digitizing. The digitized image is then used to digitally controlled deposition of ink, toner or exposure to electromagnetic energy, such as light, to reproduce images. The mathematical formulas also allow for algorithms to compress the data. It also give a method of Calibration or Color Management Systems which helps to keep images looking the same color despite where they are view or printed. One important function that the mathematical formulas allowed was the development of a common language for digital printing it is called PostScript and was developed by Adobe. To see what PostScript looks like 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 that Digital printing offers is a quicker response time due to its minimal press setup and it’s built in multicolor 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; this means that each printed piece can have different information on it providing personalization and customization unmatched by analog processes.

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.
The market is driving the desire for digital printing and therefore pushing it’s development and adoption. Print buyers want to eliminate the risks and expenses of maintaining inventory. Mass and Batch printing runs are giving way to the digital printer’s ability to have shorter print runs, mass customization, and less turn-around time.
Digital printing best serves the demand for: variable data printing, personalization, customization, less spoilage, faster proof cycle, smaller archival storage, quick response, just-in-time delivery, and short to medium print runs. While printers are still employing analog print methods they have the ability, with digital printing, to offer their customers more options and provide better service.

Screen Printing 

Screen printing is one of the early methods of printing. It involves the passing of ink or any other printing medium through a mesh or 'screen' that has been stretched on a frame, and to which a stencil has been applied. The stencil openings determine the image that will thus be imprinted. 

Screen printing was a technique first used by the Chinese almost 2000 years ago. They used human hair stretched across a wooden frame to form the screen. To that they attached a stencil made from leaves stuck together into different shapes. This was probably the first application of screen printing ever.
Subsequently, the Japanese adopted the screen printing process and used woven silk to make the mesh and lacquers to make stencils. The use of silk is where screen printing got its alternative name – Silk screening or silk screen printing.
In 1907, it was Samuel Simon near Manchester who patented the first ever industrial screen printing process. Many years later close to the First World War, John Pilsworth of San Francisco developed the Selectasine method, which basically introduced the concept of multi-color printing using the same screen. Different areas on the screen were blocked out for different color inks, thus resulting in a multi-colored image. This technique became hugely popular for printing signs and posters in large quantities.
From using hair to silk to polymer meshes, screen printing has come a long way today. The basic technique remains the same but with innovation and the introduction of electronics and computers, screen printing is no longer recognizable as the technique Simon patented. 
No matter what kind of screen printing machine you have, there is some basic equipment that will be required. The stencil or screen is of prime importance since it determines the design and image output. It refers to the frame, the mesh and the photosensitive material  on which the image is created. The Squeegee is the rubber held in a rigid handle. Ink of course. The substrate refers to the surface on which the design is to be printed. The machine base, which holds the substrate and allows the screen to print on it and is often the base of the entire screen printing unit. Here are some tips on helping you select the best screen printing equipment for your use.
The substrate or surface on which screen printing can be carried out are too many to be named. Any surface that can be stretched and printed on is a surface for screen printing. The CD covers you see are all screen printed. Beautiful cotton fabrics, silk and polyesters can all be screen printed on. Posters, signs, flyers, advertisements on buses, t-shirts and even watch dials are screen printed. Thus there are many applications of screen printing.

Oil & Water don't mix

Mole Skin Screen Printing 

Take an up-close look on how Moleskine notebooks are customized. This decorating procedure is used to create Moleskine custom edition.

Pad Printing 

Pad printing is a printing process that can transfer a 2-D image onto a 3-D object. This is accomplished using an indirect offset (gravure) printing process that involves an image being transferred from the cliché via a silicone pad onto a substrate. Pad printing is used for printing on otherwise impossible products in many industries including medical, automotive, promotional, apparel, and electronic objects, as well as appliances, sports equipment and toys. It can also be used to deposit functional materials such as conductive inks, adhesives, dyes and lubricants.

Physical changes within the ink film both on the cliché and on the pad allow it to leave the etched image area in favor of adhering to the pad, and to subsequently release from the pad in favor of adhering to the substrate.

The unique properties of the silicone pad enable it to pick the image up from a flat plane and transfer it to a variety of surfaces, such as flat, cylindrical, spherical, compound angles, textures, concave, or convex surfaces.

Above is an example of Pad Printing.

Offset Lithography Printing

Offset printing is a commonly used printing technique in which the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free.Development of the offset press came in two versions: in 1875 by Robert Barclay of England for printing on tin, and in 1903 by Ira Washington Rubel of the United States for printing on paper. Offset lithography creates clear, smooth, sharp images and text on a variety of materials. With traditional offset lithography, the blanket--that is, the part of the press which presses against the paper or printing surface--is made of a soft rubber which conforms to almost any paper surface or material, unlike systems which use inflexible metal plates for printing. Modern offset presses frequently use computer-to-plate systems, which further increase the clarity and sharpness of the image.

Advantages of offset printing compared to other printing methods include:

• Consistent high image quality. 
• Offset printing produces sharp and clean images and type more easily than letterpress printing because the rubber blanket conforms to the texture of the printing surface. 
• Quick and easy production of printing plates. 
• Longer printing plate life than on direct litho presses because there is no direct contact between the plate and the printing surface.
• Properly developed plates running in conjunction with optimized inks and fountain solution may exceed run lengths of a million impressions. 
• Cost. Offset printing is the cheapest method to produce high quality printing in commercial printing quantities.

Disadvantages of offset printing compared to other printing methods include:

• Slightly inferior image quality compared to rotogravure or photogravure printing. 
• Propensity for anodized aluminum printing plates to become sensitive (due to chemical oxidation) and print in non-image/background areas when developed plates are not cared for properly. 
• Time and cost associated with producing plates and printing press setup. This makes smaller quantity printing jobs impractical. As a result, smaller printing jobs are now moving to digital offset machines. - http://www.mr-d-n-t.co.uk/offset-lith.htm

Rotogravue 

Rotogravure is a term commonly used in the printing business. Rotogravure is the method of engraving an image to an image carrier. Images are usually engraved on a copper cylinder with rotogravure in order to be further pressed on paper reels. The process of rotogravure is often referred to as "gravure" for abbreviation.

Rotogravure presses can produce a vast range of print jobs. They can be as narrow as labels used on envelopes or shipping packages, or as wide as 12 feet (about 3.66 meters) wide rolls of vinyl. The rotogravure press is not restricted to just paper or foil. In fact, materials such as plastic or foil can be printed on through several processes that include electrostatic pull and applied pressure.

A rotogravure press includes an ink fountain engraved cylinder, a doctor blade, a dryer, and an impression roller. The engraved ink fountain cylinder is versatile enough to be changed to meet the requirements of each job layout. Generally, these changes are made by adjusting its circumference.

A printing job on a rotogravure commences when the cylinder is dipped into the ink. As it is immersed, the cells of the cylinder become filled with ink. Each rotational movement of the engraved cylinder causes it to become filled with more ink.

Litho printing

Litho printing is also known as lithography or lithographic printing or planography or planographic printing. Litho printing works on the basic principle that oil and water do not mix. Unlike relief printing and intaglio where the image and non-image areas are at different levels, in lithography there is only one surface.

In intaglio and relief printing the image areas to be printed are raised and the non-images areas form the base surface, which is lower than the image areas. However, in lithography the image areas and the non-image areas are all on the same level. The printing surface is flat.

In lithography a flat stone is treated in a manner so that the image areas attract the oil-based inks and the non-image wet areas repel the oil-based inks. When the stone is pressed against the surface to be printed on, the oily inked image areas leave an imprint of the desired design.

Litho printing is one of the few printing processes that are used as an art form and commercially as well. The litho printing process is very simple and in fact very popular with art students as project work. Commercially, litho printing or litho is often used synonymously with offset printing. Lithography is the most recent on all the major printing processes and the history of litho printing is very intriguing.

Litho printing also has many applications today. Most artists use lithography to express their creativity in a variety of forms. Commercially, litho printing has come a long way and stones have been replaced by metal plates. The basic printing process remains the same but has been upgraded with the latest technology.

The term Lithography literally means writing on stone in Greek. Litho printing was discovered in 1798 by Alois Senefelder and has grown into a popular printing process with artists and commercially.

There are several steps involved in Senefelder’s original Litho printing process. These have been modified, adapted and innovated to become the offset lithographic printing so popular today, but some arxtists feel that Senefelder’s method allows for very high creative expression. The process adds individual character to every creation that can never be replicated.

Graining

The first step in the litho printing process is graining. A limestone quarry North of Munich is the source for the world’s most superior litho stones. A litho stone must be grained after each use. A stainless steel disk called a levigator is used to grain the litho stone with a mixture of carborundum and water. The stone is then ground with finer grit leaving it smooth for the next drawing or painting. A new litho stone is generally about 10 cm thick and only 1 mm needs to be taken off for each new drawing. So a litho stone can last for a few years if kept with care.

The Artwork

Once the stone has been grained and is ready for the image, the artist must choose the image he wishes to create. The first step is to draw a barebones outline of the final image on tracing paper. Since the artwork on the stone will have to be drawn in the reverse, tracing an outline helps.

The finished line drawing is traced onto the stone using a sheet smeared with iron oxide powder to act as carbon paper. The iron oxide will leave a red outline of the image that can act as a guideline for the artist. The artist can then start drawing on the stone and filling in all the details using oil based ink or a litho pencil. In fact anything oily will leave an imprint on the stone and can ruin the image so the artist must be extremely careful when making the artwork. Sandpaper can be used to sharpen the litho pencil if fine lines need to be drawn.

If the image is to be multi colored then the process becomes far more complicated. Each color will require a separate drawing on the stone. For all the drawings to align correctly, it is vital to make registration marks. A simple black and white litho painting that requires just one run can take up to 40 hours of hard work to create.

The Chemical Processing

This is by far the trickiest part of litho printing. It is also the basic fundamental on which litho printing works: oil and water do not mix.

Lithography uses just one surface area for the image and non-image areas. Hence the two are separated using a chemical process that involves an etch. An etch is a solution of gum Arabic and nitric acid.

The first step of processing is to apply rosen powder to the image area and wipe it off. Follow this with a coat of talcum powder. The image area is then buffed vigorously. Then the etch solution is applied using a brush over the entire surface. The stone accepts this solution while the oiled image area repels the solution. The etch is left for about five minutes and then buffed off the stone.

Then comes the toughest part. An oil-based solvent is poured over the stone and the entire image is washed off. A thin layer of oil-based ink is then wiped over the image area with a clean rag. The layer of water-soluble etch gum is then removed.

A leather roller is then rolled on an ink slab and rolled over the surface of the stone. The ink is rolled several times over the stone and the stone is sponged between each roll. The stone is then allowed to dry.

The entire process from rosen powder to rolling ink is repeated several times to make the image as stable as possible before printing.

The Printing Stage

The stone is inked with the ink color that the image is to be printed in. Then a sheet of paper is laid face down on the stone. A tympan or sheet of plexiglass is placed on the paper. The press bed is then moved horizontally to a point where the scraper bar is lowered onto the tympan. As the scraper bar moves over the press bed, the image is printed onto the paper. The paper is then removed.

The stone is immediately sponged wet and the inking process repeated for another print. To print 50 copies of the same drawing you would need at least 8-10 hours for each color assuming you don’t have any problems during the entire process.

Nobody ever said litho printing was a quick process!

PAZZAZ RANT

Pazazz presents one Print Fanatic and his team who love printing! This film was based on Steve Delahoyde's film "Regrets: Boxes" which can be seen here coudal.com/boxes.php Steve is a filmmaker with Coudal Partners in Chicago (coudal.com)