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Glossary

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PACKING
In printing presses, paper or other sheet materials used to underlay the plate and/ or blanket (between the cylinder and plate or blanket), to bring the surface of the plate or blanket to the desired height to obtain proper squeeze pressure for printing: can also be adjusted to compensate for minor dimensional changes in the paper in multipass, multicolor printing jobs, but only around the circumference of the cylinder (the print length).

PACKAGING
The paper and board used for wrapping or packing goods.

PACKING LIST
A document accompanying shipments listing units shipped (rolls, skids, cartons) including identification numbers and weights.

PADDING COMPOUND
Also called edge padding glue or adhesive. A liquid adhesive mixture which when brushed or sprayed onto the side of a pile of paper adheres the sheets together along one edge, thus forming a pad.

PALLET
A pallet is a light, low platform constructed of wood or other suitable material such as solid or laminated paperboard on which various materials (e.g., paper and paperboard) can be loaded and fastened for shipment. A pallet usually consists of two platforms held apart by posts (instead of runners as in a skid) firmly affixed thereto both top and bottom are so arranged that the load can be transported by fork lift truck through entry at either side or end.

PAPER
Homogenous sheet of felted cellulose fibers, bound together by interweaving and by the use of bonding agents and made in a variety of types. A relatively homogeneous matting of primarily cellulose fibers which are formed from a water suspension on the paper machine wire and bound together by entanglement of the fibers and by bonding agents, and subsequently dried.

PAPER MACHINE
The machine upon which paper is produced from a suspension of cellulose fibers and other components in water (the furnish) by forming, pressing, drying, surface sizing (in some cases), calendering, and winding on a reel.

PAPER MASTER
See paper plates.

PAPER PLATES
A plate for an offset duplicating printing press (offset lithography) made of paper: can be called a "paper master" or "master."

PAPERSTOCK
Water slurry of various pulp fibers, dyes, additives and chemicals pumped to the paper machine for formation into sheets.

PAPETERIE
A wide variety of writing papers. used for personal correspondence and greeting cards, with good sizing for pen and ink, with good opacity arid stiffness, and that fold well.

PAPYRUS
An aquatic plant found in northern Africa. Although papyrus is considered to be the first paper, it's not, in the strict definition of the word, paper (which is a matted web of individual fibers). Rather, early papyrus "paper" was made by peeling the plant, which is constructed like an onion, and placing one layer on top of another. The natural juices acted like glue, bonding the layers and leaving the cellular structure of the plant layers intact.

PARCHMENT
Animal skins or linings stretched and prepared as writing/painting surfaces. Produces a smooth, buttery surface. Originally a writing surface made from animal skins; today made from cellulose fiber paper by dipping unsized stock in sulfuric acid, to simulate the appearance and feel of genuine parchment; called "vegetable parchment" if made from cellulose fiber paper.

PASTE-UP
Assembled on one page for photographing the various art, display and text copy for a printing job; another term used is "mechanical."

PASTE DRYER/DRIER
In ink making, a type of dryer used in inks, usually a combination of dryer compounds; see dryers.

PASTER
See splice.

PATENT COATED
Paperboard made and lined with white or colored fibers on a multi-cylinder machine, possessing a high-surface finish suitable for use in making cartons.

PERFECT
A term used to describe the binding process where the signatures of a book are held together by a flexible adhesive.

PERFECT BINDING
Binding which uses glue to hold each page in place after the folds along the spine have been cut off. A process of holding pages of a book together with glue (like padding), using no stitching or sewing. The backbones of the books are usually roughened, the adhesive applied, and finished with a wraparound cover.

PERFECTING PRESS
A printing press that prints on both sides of the page in a single pass. The terms apply to printing both sides of the paper in the same pass on the printing press. Also to print on the back of a sheet already printed on one side. Printing can be on opposite sides, either blanket-to-blanket or sequentially.

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.

PERFS
The actual holes or slots created during perforating.

PERMANENCE
The ability of a paper to resist change in one or more of its properties during storage and with aging. The resistance to paper to the destructive effects of age; also the "archival" properties of the paper or printed job. A lack of permanence is indicated by a significant loss in strength of the paper or a fade in the color or shades of the paper or printed image. The permanence of paper is chiefly dependent upon the purity of the cellulose used to make the paper, the acidity (see pH) in the paper as a result of manufacture or later contact, and the storage of the paper away from heat, light, and moisture.

PH
In chemistry, pH is a measure of the concentration of hydrogen ions in a solution, which is a measure of acidity or alkalinity. The pH scale runs from 0 to 14 and each number indicates a ten fold increase. Seven is pH neutral: numbers below 7 indicate increasing acidity, with 1 being the most acid. Numbers above 7 indicate increased alkalinity with 14 being the most alkaline. Paper with a pH below 5 is considered highly acidic. Buffered papers typically have a pH between 8.5 and 9.5. A scientific scale from 0 to 14, measured by instruments, and defining the strength of an acid or alkaline (basic) liquid. From 0 to 7 is acid-, from 7 to 14 is alkaline, while 7 is considered "neutral". i.e., neither acid or alkaline.

PHOTOCONDUCTOR
See photoreceptor.

PHOTORECEPTOR
The surface or plate in an electrostatic/ xerographic copier or printer where the image and non-image areas are distinguished. The characteristic of a photoreceptor material is that it holds an electrostatic charge on its surface in the dark, and until the charge is dissipated or erased by exposure to light; when a material has this property with respect to electrostatic charges and light, it is known as a photoconductor. See electrostatic copier/ printer.

PH SCALE
The potential of the hydrogen ion. A measure of the degree of acidity or alkalinity. A value of 7.0 is neutral on a scale of 0-14. Lower values are acidic, higher are alkaline. Book papers should be neutral or alkaline for longevity.

PICA
See point (2).

PICKING
When fibers or fillers are picked from the sheets surface during printing (low surface strength or high ink tacks). The lifting of any material off of, or out of, the paper surface during the printing impression; sometimes due to surface contamination, inadequate surface sizing, inadequate surface strength, or to the ink being too tacky. Generally, the pick will adhere to the blanket and interfere with future impressions;, can appear to be hickeys in the printed surface. For measurement of picking see I.G.T. and wax pick.

PIGMENT
Insoluble mineral or organic powder used to coat or fill paper. Many pigments are mineral and inorganic compounds used in coating to give smooth surface and opacity. 1) Minerals and other materials used in the manufacture and coating of paper, to provide desired properties. 2) Minerals and other materials, ing colorants, used in the manufacture of printing inks; finely divided solid materials.

PILING
The accumulation of paper pigments on the printing blanket. The collecting of ink particles upon rollers, blankets and plates, caused either by the inability of an ink vehicle to hold the ink pigment in suspension, or by microscopic pick and/or removal of pigment from the surface of the paper by the ink, and accumulating in the ink on the blanket, usually evidenced in the trailing edge of the image areas, resulting from extra thickness on the press blanket in the image area. If "milking" or "whitening" is severe enough, an accumulation of foreign material can occur in the nonimage areas, also creating an extra thickness there; this is also called non- image area "piling."

PINHOLES
Imperfections in paper which appear as minute holes upon looking through the sheet: accentuated by lower basis weights.

PLAIN PAPER
Bond quality uncoated paper used in plain paper copiers.

PLANOGRAPHIC PRINTING
See offset lithography.

PLATE
Depending on the printing process, the means by which the image area is separated from the non-image area; the image carrier.

PLATE CYLINDER
The cylinder on the printing press around which the plate is mounted.

PLATE GAP
See cylinder gap.

PLYBOND
Internal bond strength, measure of the resistance of a sheet of paper to delaminate or blister, due to stresses created during printing and drying.

PLY
The number of pieces of paper that make up a multi-layered, pasted or multi-cylinder-formed paperboard.

PMS color
An abbreviation for "Pantone Matching System"; an ink color system containing about 500 color swatches, each of which is identified by a color number and a formula for the ink.

POINT
1) Refers to the thickness of a sheet of paper in one thousands of an inch. See caliper. 2) A unit of printing type measurement; 0.0 138 of an inch--12 points to the pica--each pica being about 1/6th of an inch, or 72 points to the inch.

POOR SPLICE
See splice.

POOR START
Also called bad start; is when there is an obvious difference in the mechanical appearance between paper near the core and the remainder of the side of the roll.

POROSITY
A measurement of the ability of paper to allow fluids (liquids and gases) to pass through paper and paperboard, which is an important factor in ink penetration. A test which measures the time required for a given amount of air to flow through a sheet of paper; defines how open or tight the sheet of paper is with respect to the passage of air through the sheet.

POROUS PRINTING
See screen printing and mimeograph printing.

POST CONSUMER WASTE
Paper products which have served their intended end uses and have now been separated or diverted from solid waste for the purpose of recycling.

PPI
Pages per inch.

PORTRAIT MODE
A printer (usually driven by a computer) output orientation in which the printed lines run perpendicular to the direction of movement of paper. See landscape mode.

PRE-COLLATED
Sheet papers purchased in a predetermined sequence, generally for the sheet printing of business forms. See collated.

PRECONSUMER WASTE
Manufacturing wastes such as envelope cuttings, bindery trimmings, rejected unused paper, obsolete inventories, and printed paper, which have never reached the consumer.

PRESSBOARD
Manufactured on a wet machine from sulfate pulp and cotton fiber or a combination of both and finished with a high polish. Thickness ranges from .031 to .250 of an inch. Principal qualities: uniform thickness and density, excellent ply adhesion and good forming and molding properties. Available in a variety of colors.

PRESS RUN
The quantity specified for any given printing job. Also, the number of impressions made from a printing plate.

PRESS SECTION
See wet press.

PRIMARY COLORS
The additive primary colors are the three major wavelengths of light in the visible spectrum: red, green and blue, and are used in applications such as the cathode ray tube of a color television set. The subtractive primary colors are used when dealing with reflected light, such as from a full color printed piece, and are yellow, magenta, and cyan. These are the three colors of ink used in process printing. In paper making, red, yellow, and blue are the primary colors in the dyeing of paper, any two of which can be mixed together to obtain secondary colors and hues (green, orange, and violet).

PRINTABILITY
Ease with which paper can be printed to high-quality standards with the least amount of spoilage.

PRINT CONTRAST
A differential measurement of light reflectance between the image and background areas.

PRINTING INKS
Special coatings applied over specific areas of the paper surface by means of a printing press.

PRINTER
One who transfers ink onto a substrate in order to recreate a visual image. This is usually done using one of four main printing processes: letterpress, intaglio, planography, or silkscreen.

PRINTING
The act of producing an image on a page from a machine designed for that purpose, such as a printing press or a computer printer like a laser or ink jet.

PRINT ON-DEMAND
Refers to the ability to print very small quantities (50-500 copies), quickly and cost-effectively. Traditionally, printing involved an enormous amount of setup time, which resulted in it only being used for large print runs, particularly for color work. Today, the technology has advanced to the point where true on-demand printing is a reality.

PROCESS COLOR/INKS
A four color reproduction. In four color printing, the process colors are yellow, red (magenta), blue (cyan) and black. Transparent inks used in three-color and four-color printing of full color pictures or drawings; subtractive primary ink colors are yellow, magenta, and cyan. See three and four-color process.

PROCESS PRINTING
The printing from two or more halftone plates, to produce intermediate shades, hues, and tonal values. See three and four-color process.

PROHIBITIVE MATERIALS
As published by the Institute of Scrap Recycling Industries, Inc., any materials which by their presence in a packing of paper stock, in excess of the amount allowed, will make the packaging unusable as the grade specified. Additionally, this includes any materials that may be damaging to equipment.

PROOFS
Samples of copy and/or layout made at various stages of production of a printing job.

PSYCHROMETER
An instrument for determining the relative humidity of an atmosphere.

PUBLISHER
Coordinates the production of printed materials such as books, that are sold to the public.

PUFFING
See fiber puffing.

PULP
Fibrous material in papermaking produced either mechanically or chemically from fibrous cellulose raw material (wood most common).

PULPER
A device composed of a cylindrical vat in which a rotor separates the fibers and suspends them in water.

PULPING
The act of processing wood (or other plant) to obtain the primary raw material for making paper, usually cellulose fiber. Wood is the most widely used source of fibers for the paper making process. Chemical pulping is generally of the "Kraft" or Sulfate process, the Soda process, or the Sulfite process-see each. Wood pulp can also be obtained for paper making by purely mechanical means ("groundwood") or in combination with chemicals or at elevated temperatures. See semi-chemical and thermomechanical pulps; refiner mechanical pulp (RMP).

PVA (Polyvinylacetate):
An archival white glue that is stronger than gel medium. It mixes well with gloss medium. Transparent even after many coats and remains water soluble. Mixed with gel it becomes water resistant.


 
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