Printing is a collective term that refers to the various different techniques used to apply ink to a substrate or stock. Each printing technique has its own variables such as printing speed, the available range of colours and printing capacity, in addition to cost. Printing processes can easily be overlooked when a job is being designed. The designer should take in to account the printing process to ensure the visual impact of the design and budgetary constraints are met. The most common modern printing processes are explored in this book. Highlighting the suitable outcomes for each process and giving a breif description of how they work.
Lithography Lithography is a printing process where both image and non-image areas are the same level. The basis of the printing process is the fact that oil and water don’t mix. The process works by first transferring an image photographically to thin metal, paper or plastic printing plates. Rollers apply oil-based ink and water to the plates. Since the oil and water do not mix, the oil-based ink will not adhere to the non-image based areas. The inked image portion is then tranferred to a rubber blanket (cylinder) that then transfers the image onto the paper as it passes between it and another cylinder beneath the paper. The term offset refers to the fact that the image is not printed directly onto the paper from the plates, but is offset or transferred to another srface that then makes contact with the substrate. Offset-Lithography is the most commonly used commercial printing process. It is a fast process and produces consistantly clean results. The process can be sheet fed or use a continuous roll of paper, this is know as offset web litho, and allows for an even higher printing volume. Typical applications include; books, brochures, magazines, newspapers, postcards and stationary.
1. Offset lithography press with inked rollers 2. Creative Review magazine, printed using offset lithography
Flexography Printing Frequently used for printing onto plastics, foil, acetate film, brown paper and other packaging materials. The flexography process uses flexible printing plates made of rubber or plastic. The inked plates with a slightly raised image are rotated on a cylinder which transfers the image to the substrate. Flexography uses fast-drying inks and is a high-speed process. The process can print onto many types of absorbent and non-absorbent materials, and can printg a continuous pattern, such as giftwrap or wallpaper. Typical applications for flexography printing are paper and plastic bags, milk cartons, disposable cups and sweet wrappers. It is also used for envelopes, labels, newspapers and shrink wrapping.
1. Flexographic press 2. Plastic shrink wrapping printed using flexography
Gravure Printing There are two types of Gravure printing; Rotogravure and Photogravure. Rotogravure: An image is etched onto the surface of a metal plate and the etched area is filled with ink. The plate is then rotated on a cylinder that transfers the image to the paper. Photogravure: This process is now reserved for fine arts prints and is very similar to Rotogravure. The image is etched onto a copper engraving plate that is created from a transparency of a photographic image. This process produces a photographic image composed of fine lines rather than dots. Like flexography, gravure printing is often used for highvolume printing of packaging, wallpaper and giftwrap, using fast drying inks. Less common uses include the printing of magazines, greeting cards and high-voume advertising pieces.
1. Gravure printed shrink sleeves allow for full design coverage. 2. Rotogravure cylinder being engraved.
Lino-cut Printing Lino-cut is specifically a low volume, relief printing method. It consists of cutting an image into a thin piece of linoleum using a variety of tools and gouges to remove the areas of the design that remain colourless. Ink is then applied to the surface of the lino with a roller. Only the surface of the lino left uncut and in ‘relief’ will recieve ink when rolled and therefore print. Paper is then applied to the inked surface and the ink is transferred using a roller press or a baren (a small disk which burnishes the back of the paper to press the ink onto it). The next layer of lino is them removed and the printing process repeated. Each succeeding colour is applied to the block, printed, then carved away, getting darker each time. This type of printing process calls for extreme accuracy and patience as previous steps cannot be repeated as the design is carved away each time. Lino-cut printing is primarily used as a method of fine art printing. However, it does lend itself to the production of simple logos and graphic imagery.
The images on these book covers are lino-cut designs paired with letterpress type. The lino-cut image was produced by Chris Brown, the cover designed by Webb & Webb
Letter Letterpress is a method of relief printing whereby an inked, raised surface is pressed against the substrate. Letterpress was the first form of commercial printing, and much print-specific terminology derives from it. The raised surface theat makes the impression is typically made from pieces of type, but photo-engraved plates can also be used. Letterpress printing can offen be identified by the slight indentation made into the substrate. A defect of letterpress printing is that the impression from raised surface varies each time it is pressed against a substrate, giving the characters a uniqueness where each is subtly different, which is appealing to designers. This defect has become a popular style, to the extent that an original design is printed letterpress, and the result is scanned and reproduced in offset-lithography to produce multiple copies of it. Letterpress has it’s roots in the initial conception of moveable type. The majority of commercial opportunities for letterpress have deied out, but letterpress is enjoying a revivial in the form of bespoke stationary and poster design.
1. Two colour greeting card by Letterpress Delicasies. Printed by hand on a mid-century Vandercook press. 2. Two colour love birds illustration. Printed on a Golding Pearl#3
Silk Screen Screen printing by hand is not a high-volume printing method because each colour that is applied to the substrate has to dry before another can be applied, but it is flexible method which can be used to apply a design to virtually any substrate. Silk-screen printing allows more viscous inks to be used, which can provide additional tactile qualities to piece of work. The basic process involves a screen of thin nylon mesh, which is coated with a light sensitive emulsion which blocks the holes in the mesh. The image that needs to be printed is outputted by camera or digital printer (or can be drawn by hand). The positive image and emulsion coated mesh are placed together and exposed to ultra-violet light. The screen is then washed with a jet-washer, which removes the emulsion which has not be hardened by the ultraviolet light. This leaves an open ‘stencil’ through which the printing ink is forced. The screen can be manoeuvred by hand or fitted to a hinged press and the substrate placed in position underneath it. Ink is then passed through the mesh using a squeegee and the positive image is printed onto the substrate. Commonly used to print designs onto t-shirt and other fabrics. It is also popular for prouducing graphic prints and canvas based artworks. It is frequently used to print signs and displays, and even balloons.
1. Two colour silk screened poster by Anti-Graphic 2. Four colour silk screen poster by Stickhouse Press
Pad Printing Pad printing is a process that uses an amalgamation of features from gravure, screenprinting and rubber stamp printing. It is adaptable to a variety of shapes and contours, yet very fine detail and precise copy can be achieved. Four colour process is obtained with exact registration and is ideal for decorating toys, plastic housewares and injection moulded components. Plastics, ceramics and metals can be marked with this process and can be fully or semi-automated. The unique features of pad printing include; being able to print onto curved, convex and concave, recessed or discontinuous surfaces. It is capable of printing 90 degree wraparound on 3D objects and can be used on a wide variety of subtrates. Pad printing is a fast and economic printing process which allows for objects the be printed onto at the end of their production cycle. Commonly used for printing onto pens, computer keyboards, electronics and a wide variety of other products.
1. Apple Mac keyboard 2. Dunlop golf balls
An Introduction to Print Information collated by Alexandra Bucktin Design Context 2010