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Casey's Print Dictionary

General Info Tips & Tricks tips and tricks Print

The Printing Industry is full of jargon that serves to confuse and frustrate customers and outsiders. Below are some common terms used in the printing industry.

Against the grain: Folding or feeding paper at right angles to the grain direction of the paper. On some stocks folding against the grain can result in quality control issues.

Aqueous Coating/Flood Coat: A coat of varnish applied to a sheet on press that protects a printed piece from scuffs and scratches.

Basic size: All papers have an assigned basic sized. For example; 25 x 38 for book papers, 20 x 26 for cover papers, 22 1/2 x 28 1/2 or 22 1/2 x 35 for bristols, 25 1/2 x 30 1/2 for index.

Basis weight: The weight in pounds of a ream (500 sheets) of paper at basic size (see above). Example, 50# Book paper: 500 sheets at basic size of 25" x 38" weighs 50 lbs.

Blanket: A rubber-surfaced fabric wrapped around a cylinder that is used to transfer an image from the plate to the paper. A primary component of offset printing.

Bleed: An extra amount of printed image that extends beyond the trim mark of the sheet or page. When the sheet is cut to size the image shows all the way to the edge of the sheet.

Chalking: A condition of printing attributed to improper drying of ink. Pigment dusts off because the vehicle has been absorbed too rapidly into the paper, creating a “chalky” appearance.
CMYK: (Cyan, Magenta, Yellow, Black) The subtractive process colors used in color printing. Black (K) is added to enhance color and contrast.

Coated paper: Paper that has an applied surface coating resulting in a smooth finish. Surface appearances may vary from eggshell to glossy.

Contract proof: A color proof of the job representing an agreement between the printer and the customer regarding how the printed product will look.

Creep: Occurs when multiple signatures are collated together causing the middle pages of a folded signature to extend beyond the outside pages. Your printer has to compensate for it during layout and imposition. Also known as “push out.”

CTP: (Computer-to-Plate) Computer-to-Plate systems or platesetters eliminate the need for having a separate film-to-plate exposure system.

Curl: The distortion of a sheet due to differences in structure or coatings from one side to the other, or to absorption of moisture on an offset press. Can result in complications in post press operations.

Dummy: A preliminary sample of a printed piece, showing images and text. Can be blank pages used to simulate final layout, size, and format.

Dampening system: Component of an offset press that transfers fountain solution to the printing plate.

Die-cutting: The process of using sharp steel rules to cut special shapes for labels, boxes, and containers from printed sheets.

Digital printing: Printing using plate-less systems that are imaged by digital data from prepress systems. Utilizes toner, ink-jet, and other printing processes.

Dot gain: A printing defect in which dots print larger than planned, causing darker tones or stronger colors. Dot gain can be caused optically or mechanically. During plate exposure, light scatters, causing 3-5% optical dot gain. Then, during the printing process, paper and realities of the printing process cause the ink to spread, creating mechanical dot gain.

Feeder: The section of a printing press that separates the sheets from each other and feeds them into the printing units.

Flexography: A primarily lower-quality relief printing process used to produce images on packaging.

Folio Lip:
An intentional overlap on a folded signature that allows it to be fed through a binding machine.

Form rollers: The rollers, either inking or dampening, that directly contact the plate on a printing press.

Fountain solution: A solution of water, a natural or synthetic gum, and other chemicals used to dampen the plate and keep non-image areas from accepting ink. A main element of Lithography.

Ganging: Printing multiple print projects on a single sheet in order to reduce costs on each individual project.

Gathering: The collating of multiple signatures into proper sequence. A common post-press operation.

Grain: The direction in which most fibers lie, attributed to the direction in which the paper is made on a paper machine.

Gravure printing: A high quality printing process that uses engraved cylinders to transfer images to substrates.

Grippers: A component of a sheet-fed printing press. Grippers are metal fingers that clamp on to the paper and control its’ flow through the press.

Groundwood: A mechanically prepared wood pulp used in the manufacture of newsprint and other publication grade paper. Groundwood papers are generally used for print projects which do not require more expensive, higher end papers.

Halftone: The reproduction of continuous-tone images, through a special screening process, that converts the image into dots of various sizes and equal spacing between centers (AM or Amplitude Modulated screening), or dots of equal size with variable spacing between them (FM or Frequency Modulated screening), or some combination thereof.

Hickeys: Spots or imperfections in the printing due to dirt on the press, dried ink skin, paper particles, etc. Primarily a condition of offset printing.

Hydrophilic (Water receptive):
Non-image areas, for example, on an offset plate, that "love" water. The opposite is hydrophobic. Synonymous with Oliophobic (Oil/Ink repellent).

Hydrophobic (Water repellent): Image areas, for example, on an offset plate, that "hate" water. The opposite is hydrophilic. Synonymous with Oliophillic (Oil/Ink receptive).

Imposition: In image assembly, the calculated positioning of pages on a signature so that after printing, folding, and cutting, all pages will appear in the proper sequence.

Impression cylinder: The cylinder on a printing press that applies the image onto the substrate. The image is transferred to the impression cylinder from the inked plate in direct printing, or the blanket in offset printing.

Make-ready: All work done to set up a press for printing. Paper is run through the press to bring it into registration.

Newsprint: Paper made mostly from groundwood pulp and small amounts of chemical pulp.

Offset: Short for offset lithography. A printing process in which in blanket acts as an intermediary to transfer an image from the image carrier to the substrate.

Opacity: That property of paper that minimizes the “show-through” of printing.

Overprinting: Printing over an area that already has been printed on.
Pagination: The process of performing page makeup.

PDF (Portable Document Format): Created by Adobe Systems, a PDF is a universal portable file format created to speed and make easier the process of document exchange. The PDF format is a printing industry standard.

Perfect bind: A type of binding that glues the edge of sheets to a wraparound cover.

Perfecting press: A printing press that prints both sides of the paper in one pass through the press.

Picking: The lifting or “picking away” of the paper surface during printing. It occurs when the pulling force (tack) of ink is greater than surface strength of paper.

Plate cylinder: The cylinder of a press on which the plate is mounted. Each cylinder prints one color of ink or may be used for varnish or coating.

Platesetter: An image recorder that images directly on plate material using a laser. Platesetters have eliminated the necessity for a traditional film-based imaging system, and have greatly reduced the time and labor needed to produce printing plates.

PMS (Pantone Matching System®): Color charts that have more than 1000 preprinted color patches of blended inks, used to identify, display and define special "branded" colors. PMS is the standard ink color system used by commercial printers.

PostScript: A page description language developed by Adobe Systems to describe and define a page image for printing. It handles both text and graphics. A PostScript file is a purely code-based de¬scription of a page.

Preflighting: The evolution and analysis of files containing information for a printed piece. Proper preflighting can eliminate or prevent problems later on in the printing process.

Process colors: The use and mixing of the primary subtractive colors (CMYK) to reproduce images and colors on press.

Raster image processor (RIP): A combination of computer software and hardware that controls the printing process by analyzing a digital image file and instructing a printing or platesetting device how to create the images.

Ream: Five hundred sheets of paper.

Register marks: Crosses or other targets applied during printing, used for registering of two or more colors in process printing.

Saddle stitch: A common bindery operation that uses metal wire to stitch gathered signatures together to create a booklet.

Scum: A film of ink printing in the non-image areas of a plate, usually attributed to a problem with fountain solution.

Signature: The name given to a printed sheet after it has been folded.

Skid: A platform support for a stack of sheets of paper, signatures, or finished books.

Tack: The property of cohesion between particles or ink; the separation force of ink needed for proper transfer and trapping on multicolor printing presses. How “sticky” an ink is.

Trapping: The ability to print a wet ink film over previously printed ink. During prepress, the amount of overprinting colors need to overlap is calculated in order to eliminate white lines between colors in printing.

Variable Data Printing (VDP): An emerging and growing segment of the printing industry. VDP is the ability of each printed page to can contain different information, text, or images.

Varnish: A thin, protective coating applied to a printed sheet for protection or appearance. A “spot varnish” applies varnish only to specific areas of a sheet to highlight that specific spot.

Viscosity: A broad term used to explain how fluid an ink is. A highly viscous ink, such as litho ink is more solid and does not easily flow, while an ink with low viscosity, such as flexo ink, is much more liquid.

Web-to-Print: A customer-printer relationship that uses the Internet as the medium for exchange. Also called “W2P” and “web2print”.

Web printing: Has nothing to do with the World Wide Web. In this case, “Web” refers to a type of printing press, which uses paper off a large roll, rather than pre-cut sheets. The paper is unrolled and is fed through the press as a “web”.

Work-and-Tumble: To print one side of a sheet of paper, then turn it over from gripper to back using the same side guide and plate to print the second side.

Work-and-Turn: To print one side of a sheet of paper, then turn it over from left to right and print the second side using the same gripper and plate but opposite side guide.