Packing gauge
A device for determining the relationship between the height of the plate or blanket and the cylinder bearers.

Page makeup
In stripping, assembly of all elements to make up a page. In digital imaging, the electronic assembly of page elements to compose a complete page with all elements in place on a video display terminal and on film or plate.

Page proofs
Initial impression of a page pulled for checking purposes before the entire job is run.

Pagination
In computerized typesetting, the process of automatically performing page makeup.

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

PANTONE MATCHING SYSTEM® (PMS)
Based on a color swatchbook system that gives printers recipes for how to mix inks to match the colors shown, Pantone is the most widely used ink color matching system in America.

Panchromatic
A type of film equally sensitive to light in all colors.

Paper
A matted web of cellulose fibers formed into a dry sheet.

Paper consultant
A specification representative from a paper mill or merchant who can offer expert advice on how to choose and use a paper for a specific job.

Paper dust
Paper dust, also known as linting, is caused by any one of several sources, e.g., dust on paper left by dull cutting blades at the paper mills, a printer's failure to back trim, contaminating flecks of dried ink, the use of too much offset powder or dust from the plant environment. Loose flecks of fiber, filler and/or coating can stick to the printing blanket and prevent ink from properly reaching the paper surface.

Paper grade
Papers manufactured to fit within a group of type of papers. Each grade of paper uses basically the same fiber, color, additive and chemical composition.

Paper machine
Machine on which paper is manufactured, dried, wound on rolls and slit to appropriate lengths.

Papermaking
Invented in China by T'sai Lun some 2,000 years ago, papermaking still follows the same basic procedures. Today, wood chips are cooked with chemicals to release cellulose fibers and to dissolve lignin, then washed to remove impurities. Most printing papers are then bleached to lighten the color of the pulp. Pigment, sizing and fillers are added, along with large quantities of water. The resulting slurry, which is 99% water, is cascaded onto the continuously moving forming fabric of the Fourdrinier paper machine. Side-to-side shaking distributes the slurry, forming a tangled web of fiber as the water drains off. A wire mesh roller, called a dandy roll, moves over the surface to modulate the turbulence and smooth the top side of the paper. A felt blanket absorbs more water from the paper and sends the sheet on through a channel of hot metal drums that dry and press the paper at the same time to give it a more even-sided finish. At this point, the paper is fully dry and ready for off-machine processes such as coating, embossed finishes and supercalendering.

Paper master
A paper printing plate used on an offset-duplicator. The image is made by hand drawing, typewriter or electrophotography.

Paper merchant
A business that operates as the intermediary between paper manufacturers and users of the paper. Merchants usually warehouse the products and then distribute to those who purchase the paper.

Paper stock
A mix of pulp fibers, water, additives, chemicals and dyes that will be pumped into the paper machine to form paper.

Paper surface efficiency
Measure of the printability of a sheet of paper, which is dependent upon the amount of ink the paper absorbs, the smoothness of its surface and the evenness of its caliper.

Papeterie
A paper used for greeting cards, stationery, etc. that is distinctive from regular stock in that special watermarks and embossing may be used.

Papyrus
The Egyptians used this aquatic plant to create a writing sheet by peeling apart the plant's tissue-thin layers and stacking them in overlapping, cross-hatched pieces to form a sheet. Despite giving us the word "paper," papyrus is not a true paper.

Parallel fold
Any series of folds in sequence, made in parallel fashion.

Parchment
To simulate the look of ancient parchment, which was made from animal skin, text and cover versions are made with a variegated surface, translucent colors and rigid feel. Parchment is often used for diplomas, certificates and contracts.

Pasted
Pasted grades are those grades of paper or paperboard made up of layers pasted together. The process is machine operation used to combine sheets of the same or different papers into a single thickness.

Paste-up
Assembling on one page for photographing various art elements for a print order.

Patch material (envelopes)
Translucent or clear material covering window (e.g., Plastine or Cello).

Percent tensile
A paper's tensile strength expressed in percentage points.

Perfect binding
Method of binding in which all the pages are converted to single sheets. They are then held in a clamp and attached to a cover with an adhesive.

Perfecting press
Commonly referred to as Perfector. Press that prints both sides of the sheet of paper at the same time. On the offset press, each cylinder serves as the impression cylinder for the other.

Perforate
Punching a series of holes or slits in a line in the paper to weaken it so tearing will occur easily along that line. Also, the making of slits in paper during folding, at the fold, to prevent wrinkles and to allow air to escape.

Perforation tear strength
The ease or difficulty with which a perforation may be torn.

Permanence
In paper terminology, permanence refers to the ability of paper to retain - for a given period of time - desirable properties such as color and folding endurance. Prolonged exposure to light, humidity and adverse temperatures will affect the permanence of paper.

Permanent Paper
In order to be considered permanent (relating to permanence of paper for publications and documents in libraries and archives), uncoated papers must meet the following criteria, which ensure that they will last several hundred years under normal conditions: (1) pH minimum of 7.5, (2) tear index of 5.25 mNm2/g, (3) alkaline reserve equivalent to 2% calcium carbonate based on oven dry weight and (4) less than 1% lignin by weight.

Petroleum-based inks
Inks that use petroleum as the vehicle for carrying pigment. Oil-based inks are giving way to vegetable-based inks, which are kinder to the environment.

pH
The measure of the acidity or alkalinity of a material (e.g., solutions or paper). A paper with a pH of over 7.0 is considered acid-free or alkaline. A sheet below 7.0 is considered acidic. A pH value of 7.0 is neutral.

Photoengraving
In letterpress, the process of creating a relief plate by photochemical process.

Photomechanical
In platemaking, pertaining to any platemaking process using photographic negatives or positives exposed onto plates or cylinders covered with photosensitive coatings.

Pica
Unit of measure, approximately 1/6 of an inch, used in graphic arts. Twelve points make one pica.

Pick out (also see picking)
A problem on press caused by paper with weak bonding strength or poor sizing. As the ink hits the paper, it picks off some of the fibers and transfers them onto the printing blanket, creating "hickeys" (printing blemishes) on subsequent sheets.

Pick resistant
Paper with good bonding strength that keeps fibers in place as the sheet goes through the press.

Pick tester
An instrument designed to measure the pick resistance of paper, through the use of inks with varying degrees of tack.

Picking (also pick out)
Fibers in the paper that tend to pull away from the surface during the printing process. This may be an indication of a paper with low bonding/surface strength or the use of an ink with too much tack for the paper it is printed on.

Pigment
In printing inks, the fine solid particles used to give inks color, transparency or opacity. Also, an ingredient added to pulp to increase the brightness and opacity of white paper. Pigment dyes are also used in some colored grades to create deep colors.

Pile feeder
A mechanism on printing presses and folders that feeds paper automatically from the top of the pile.

Piling
When a press is running too much ink it causes build-up on the press rollers, plate or blanket and makes printing hard to control. Piling also refers to the accumulation of dust or coating on the blanket of an offset press. Piling affects how ink lays on a paper, overall color evenness and can also lead to set-off.

Pin register
In copy registration, the use of accurately positioned holes and special pins on copy, film, plates and presses to ensure proper register or fit of colors.

Pinholes
Pinholes occur when ink fails to cover a substrate surface completely, leaving small holes or imperfections in the printed area. This condition is often caused by the presence of foreign matter on the paper or other substrate surface during manufacture.

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

Planography
A process for printing from a smooth surface, such as a printing plate, as used in offset lithography.

Plate
Short for printing plate, which is the thin metal sheet that carries the printing image, whose surface is treated so that only that image is ink5-receptive.

Plate cylinder
The cylinder of a press on which the plate is mounted.

Plate finish
A term describing a smooth, hard-finished paper. Plate is a popular choice for business cards, invitations, announcements and baronial panel cards.

Plate flaking
This occurs primarily with offset plates, with the copper-plate or image area having a tendency to chip off, the chip then moving into the ink train, plate or blanket.

Platen press (jobber)
A letterpress on which the printing form and the paper lie flat throughout the printing process.

Plugged
Refers to a printing condition characterized by the loss of dot reproduction. No dots are visible.

Ply
A single layer of paper. A term used when several sheets of paper are laminated together to form a board.

PMS® (PANTONE MATCHING SYSTEM®)
An ink color system widely used in the graphic arts. There are approximately 500 basic colors, for both coated and uncoated paper. The color number and formula for each color are shown beneath the color swatch in the ink book.

Point
When measuring the thickness of paper, one point is 1/1000 or .001 inch.

Poor trapping
In printing, the condition in wet printing in letterpress and lithography when less ink transfers to previously printed ink than to unprinted paper.

Porosity
The degree to which a paper will allow the permeation of air, gas or liquid, as determined by the compactness of its fibers.

Post-consumer fiber
Paper that has reached its intended end-user and is then discarded. The paper recovered from curbside collections is considered to be post-consumer. Trim and scraps from the print shop are not. The print shop is not the "intended end-user," but is adding value to the paper that will eventually reach the end-user.

Post-consumer recycled paper/fiber
Recycled paper made from waste paper materials recovered after use by consumers.

Ppi
Pages per inch or the number of duplex printed sheets in a one-inch stack of paper.

Precision sheeting
The conversion of paper rolls into finished sheet sizes in a single operation.

Pre-consumer fiber
Paper that is recovered before it reaches the end-user. Typically this includes converters, printers and others who are adding value but are not the intended end-user. Pre-consumer does not include mill manufacturing broke as pre-consumer, but it may include mill scrap from finishing and converting operations.

Pre-consumer recycled paper
Paper recovered after the papermaking process but before use by a consumer.

Preflight
In digital pre-press, the test used to evaluate or analyze every component needed to produce a printing job. Preflight confirms the type of disk being submitted, the color gamut, color breaks and any art required (illustrations, transparencies, reflective photos, etc.), plus layout files, screen fonts, printer fonts, EPS or TIFF files, laser proofs, page sizes, print driver, crop marks, etc.

Prescreen
A lower contrast halftone, printed on glossy photographic paper for direct paste-up with line copy, to avoid stripping of a halftone negative into a line negative.

Pre-separated art
Art that has a separate overlay prepared for each color in the illustration.

Press
During manufacture the paper web passes through sets of rolls called the press. This occurs either to remove water from the web at the wet press, to smooth and level the sheet's surface at the smoothing press, or to apply surface treatments to the sheet at the size press.

Prepress proof
A trial print made photographically before the plate has been made. Also see off-press proofs.

Press proof
A few sheets that are run off the press for a final proof. Press proofs are generally printed on the paper stock that will be used in order to see how the images will appear on the sheet.

Press sheet
The full-size sheet of paper is selected for a job to be printed on a sheet-fed press. The sheet size is usually slightly larger than the negative flat, to allow for gripper and trim margins.

Primary colors
The three basic colors - yellow, red and blue - from which all other colors can be mixed.

Print quality
A term describing the visual impression and quality of a printed piece, which is affected by the paper, ink press and skill of the press operators. In paper, the properties of the paper that affect its appearance and the quality of reproduction.

Print smoothness
The even and consistent continuity of a paper's surface. How the paper receives the ink is affected by the smoothness of the surface.

Printability
How well a particular sheet appears after the printing process in regards to ink receptivity, uniformity, smoothness, compressibility and opacity. It involves a complex interrelationship of many paper properties. Best methods for predicting printability are those that simulate actual printing conditions and that are reproducible from test to test.

Printer
Generic term applied to data-processing devices that produce full-size hard copy from computers. Several printers are used. Among impact printers: serial printers, line printers, chain printers, bar printers, wheel printers and matrix printers. Non-impact printers, like ink jet printers, are based on printing principles similar to those employed in cathode ray tubes.

Printing
The transfer of ink onto paper or other materials to reproduce words and images. The choice of a printing process depends upon the size of the run, the complexity and quality of the camera-ready art, the number of ink colors, the paper stock and the level of quality desired.
Dry Offset: Similar to wet offset, but requires a coarser screen, normally 100 to 120 lines per inch. Uses a printing plate with a raised surface. Produces printing quality higher than flexography but lower than wet offset.
Flexography: A form of rotary letterpress, using flexible rubber or photopolymer plates. Fast drying process, suitable for screens with 65-105 lines. Good quality and clarity, but below wet or dry offset.
Jet Printing: Allows for fast, high-quality turnaround.
Letterpress: Similar to flexographic printing. Uses screens of 65 to 85 lines. One of the least expensive printing processes. Good quality and clarity.
Lithograph: See Offset Printing.
Offset Printing: Also known as wet offset or lithography. Offers highest degree of precision, clarity and quality. Uses screens of 133 lines or more. Uses a flat printing plate.

Printing pressure
The force or pressure between the blanket cylinder and impression cylinder required to transfer the ink from the blanket to the paper.

Private watermark
A watermark that has been specially designed and manufactured for a business, institution or individual. A symbol of distinction and prestige, private watermarks also offer protection against forgeries since the corporate logo becomes a translucent mark in the paper itself.

Process chlorine free (PCF)
This is generally a recycling decolorizing and bleaching done without the use of chlorine or chlorine compounds. The usual chemicals are peroxide, ozone and oxygen.

Process colors
In four-color process printing, the subtractive primaries: magenta (process red), cyan (process blue), yellow and black inks are used.

Process inks
Transparent inks, finely ground and manufactured for use in the four-color process.

Process plates
Two or more color plates in combination that produce other colors and shades.

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

Progressive color proofs (progs)
Proofs of colors separation negatives that have been exposed to offset plates and printed using process inks. Presented in the sequence of printing, i.e., (1) yellow plate alone, (2) red alone, (3) yellow and red, (4) blue alone, (5) yellow, red, and blue, (6) black alone, (7) yellow, red, blue, and black. The preferred way for checking the color of the separation negatives using the same inks, paper, ink densities and color sequence as intended for the production run.

Proofread
Reading and correcting proofs early in production.

Proofs
Samples of copy and layout produced at various stages of production. Following internal inspection, proofs are sent to the customer for approval.

Proprietary mill brand
Paper retaining the name of the owner of the mill.

pt.
The abbreviation of point. A measurement of the thickness of paper.

Pull test
A test performed on perfect-bound books to determine the amount of pull pressure required to remove a page from the binding; used to verify that pages are securely bound.

Pulp
Cellulose fiber material produced by chemical or mechanical means from which paper and paperboard is manufactured. Origins of this cellulose fiber are many and can include wood, cotton, straw, jute, bagasse, bamboo, hemp, various leaf fibers, reeds, etc.

Pulping wood
To separate cellulose fiber from lignin, tree logs are chipped and processed into pulp either by mechanical or chemical means.
Mechanical pulping: Also known as groundwood pulping, this method simply grinds wood into short fibers without removing any lignin or impurities that cause paper to yellow, crack and disintegrate over time. Such paper is used primarily for newsprint.
Thermo-mechanical pulping: Steam pressure is used to soften wood chips before they are mechanically ground. Steaming helps to separate the cellulose fibers better than grinding alone.
Chemical pulping: Wood chips are cooked with chemicals to separate cellulose fibers and dissolve lignin. Papers made from this process are known as free-sheet.

Pulpwood
Wood, in the form of logs or shorter lengths, that is suitable for the manufacture of wood pulp from which to make paper.