printingPacking On printing presses, material, usually special paper, used to underlay the image or impression cylinder in letterpress, or the plate or blanket in lithography, to get proper squeeze or pressure for printing.

Page buffering The ability to spool an entire image to disk and print at one time for uninterrupted flow.

Page count The total number of pages in a book or other publication including blanks.

Page description language (PDL) In digital prepress, a computer language designed for describing how type and graphic elements should be produced by output devices. PostScript is the most commonly used PDL in printing.

Page makeup Assembly of all elements to make up a page. In digital imaging, the electronic assembly of all page elements to compose a complete page with type, graphics, images, and color in place on a display screen for output to plate or printer.

Pagination The process of performing page makeup automatically.

Palette The collection of colors or shades available to a graphic system or program.

Panchromatic Photographic film sensitive to all visible colors.

PC (Personal Computer) Desktop and laptop computers. Desktop units are sometimes called workstations.

PDF (Portable Document File) Adobe's PDF is a universal electronic file format, modeled after the PostScript language and is device- and resolution-independent. Documents in the PDF format can be viewed, navigated, and printed from any computer to almost any printer regardless of the fonts or software programs used to create the original. Printing industry workflows are now primarily PDF-based.

PDL See page description language.

PE's Abbreviation for printer's errors. PE's are changes made to your job after it's been at the printer's for corrections to something the printer (not you) is responsible for. Author's alterations (AA's) are changes that you, the customer (or author) makes to a job after a printer has already processed it (usually on a proof). Customers pay for AA's, not for PE's. See AA's.

Pearlescent Coating From Sappi's Standard #5: A coating used to add luster and iridescence to an image.

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.

pH A reference number used for expressing the acidity or alkalinity of solutions. A value of 7 is neutral in a scale ranging from 0 to 14. Solutions with values below 7 are acid. Those above 7 are alkaline.

Phosphorescent Coating From Sappi's Standard #5: Essentially absorb daylight and glow in the dark.

Photoconductor In digital imaging, special materials used in electrophotography that are light sensitive when charged by a corona. They then convert light energy (photons) into electrical energy (electrons),

Photopolymer coating In photomechanics, a plate coating consisting of compounds that polymerize on exposure to produce tough abrasion-resistant plates capable of long runs especially when baked in an oven after processing.

Pica Printer's unit of measurement used principally in typesetting. One pica equals approximately 1/6 of an inch.

Picking The lifting of the paper surface during printing. It occurs when the pulling force (tack) of ink is greater than surface strength of paper.

Pigment The fine solid particles used to give inks color, transparency, or opacity.

Piling The building up or caking of ink on rollers, plate, or blanket; will not transfer readily. Also, the accumulation of paper dust or coating on the blanket of an offset press.

Pixel Short for "picture element." A pixel is the smallest resolvable point of a raster image. It is the basic unit of scanning and digital imaging.

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. Platesetters currently available use lasers to expose or image paper, polyester, or aluminum plates.

PMS (Pantone Matching System®) Color charts that have more than 1000 preprinted color patches of blended inks, used to identify, display, or define special "branded" colors. The Pantone Goe? system adds another 2000+ brand colors. PMS is the standard ink color system used by commercial printers. Ask to see/use a PMS swatchbook when spec'ing ink colors for your job. If you can't find a color you want among these 3000+ PMS offerings, there's something seriously wrong.

Point Printer's unit of measurement, used principally for specifying type sizes and leading. There are 12 points to a pica and approximately 72 points to an inch.

Poor trapping The press condition in wet printing in letterpress and lithography when less ink transfers to previously printed ink than to unprinted paper. Also called undertrapping.

Porosity The property of paper that allows the permeation of air, an important factor in ink penetration.

Portrait The vertical orientation of a page format as opposed to landscape horizontal orientation.

Position proof Color proof for checking position, layout, and/or color breakout of image elements. Once called a blue line or salt print. Today, PDFs are used in some cases.

Positive An image in which the dark and light values are the same as the original. The reverse of a negative. Negatives and positives are visual opposites.

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

Pre-press proofs See off-press proofs.

Preflighting The evaluation and analysis of every component in a file needed to produce a printing job. Pre-flight confirms the data being submitted, color gamut, color breaks, and any art required (illustrations, transparencies, photos, etc.), plus layout files, fonts, image files, proofs, page sizes, print driver, crop-marks, etc.

Press proofs In color reproduction, a proof of a color subject made on a printing press, in advance of the production run.

Pressure-sensitive paper Material with an adhesive coating, protected by a backing sheet until used.

Primary colors See additive primaries, subtractive primaries.

Print quality A term describing the visual impression of a printed piece. In paper, the properties of the paper that affect its appearance and the quality of reproduction.

Printer spreads Each page needs to be printed next to it is true opposing page, versus the way it will look in the end after it is bound. Use your mock version as your guide and double check with the printer to make sure you are doing it right before you create the printer spreads.

Printer's Devil A Printer's Devil is a pressman's assistant; an older term referring to the pressman's assistant or helper (sometimes referred to now as a catcher) when a press is being run.

Process colors The subtractive primaries: yellow, magenta, and cyan, plus black in four-color process printing. Referred to as CMYK.

Process printing Printing from a series of two or more plates to produce intermediate colors and shades.