Glossary

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Packing
In printing presses, 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 in a continuous motion.
Page make-up
In stripping, assembly of all elements to make up a page. In computerised typesetting and CEPS, 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.
Pagination
In computerised typesetting, the process of performing page make-up automatically. The allocation of page numbers to the images of a book.
Palette
The collection of colours or shades available to a graphic system or program.
Panchromatic
Photographic film sensitive to all visible colours.
Pantone Matching System
(PMS) The most common system for colour specification and colour matching.
Parchment
Parchment was originally the treated skin of a kid. Paper parchment, (imitation parchment), is a heavyweight paper or board with a mottled or lumpy formation. Parchment is commonly used for presentation documents and folders. The sheet should accept embossing; foil stamping, and colour printing as well as caligraphy.
Paste drier
In ink making, a type of drier, and usually a combination of drying compounds.
Perfecting press
A printing press that prints both sides of the paper in one pass through the press.
PH
A number used for expressing the acidity or alkalinity of solutions. A value of 7 is neutral in a scale ranging from 0-14. Solutions with values below 7 are acid, above 7 are alkaline.
Photocopying
An electronphotographic copying process that uses a corona charged selenium photoconductor surface, electrostatic forces and dry or liquid toner to form an image. Also known as Xerography.
Photomechanical
Pertaining to any plate making process using photographic negatives or positives exposed onto plates or cylinders with photosensitive coatings.
Photopolymer coating
In photo-mechanics, a plate coating consisting of compounds, which polymerise on exposure to produce tough abrasion-resistant plates capable of long runs especially when baked in an oven after processing.
Phototypesetting
The method of setting type photographically.
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 pulling force (tack) of ink is greater than surface strength of paper.
PICT
A standard data format in which most Macintosh illustrations are encoded.
Pigment
In printing inks, the fine solid particles used to give colour, transparency or opacity.
Pilling
In printing, 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 offset press.
Pin register
The use of accurately positioned holes and special pins on copy, film, plates and presses to ensure proper register or fit of colours.
Pixel
In electronic imaging, a basic unit of digital imaging.
Plate cylinder
The cylinder of a press on which the plate is mounted.
Platesetter
Imagesetter for making plates.
Point
Printer's unit of measurement, used principally for designating type sizes. These re 12 points to a pica, approximately 72 points to an inch.
Poor trapping
In printing, the condition in wet printing in letterpress and lithography when less ink transfers to previously printed ink than to non-printed paper. Also called undertrapping.
Porosity
The property of paper that allows the permeation of air an important factor in ink penetration.
Portrait
Where the finished size is deeper than it is wide. (as in a painting).
Positive
In photography, film containing an image in which the dark and light values are the same as the original. The reverse of negative.
Post Consumer Waste (PCW)
Term used to describe paper which becomes waste after reaching the final consumer of the paper or paper product.
Postscript
A computer description language that allows a programmer to create complex pages using a series of commands.
Postscript-compatibles
Any software program that translates statements written in the Postscript page-description language. Sometime called a Postscript clone.
Pre Consumer Waste
Term used to describe paper which becomes waste before the finished product reaches the final consumer of that product.
Pre-press proofs
See Off-press proofs.
Presensitised plate
In photo-mechanics, a metal or paper plate that has been pre-coated with a light-sensitive coating.
Press proofs
In colour reproduction, a proof of a colour 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. Also known as self adhesive.
Primary colours
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.
Process colours
In printing, the subtractive primaries: yellow, magenta and cyan, plus black in four-colour process printing.
Process lens
A highly corrected photographic lens with a flat field for graphic arts line, halftone and colour photography.
Process printing
The printing system using cyan, magenta, yellow and black (CMYK) to produce multi-coloured work.
Program
In computers, sequence of instructions for a computer. Same as software.
Progressive proofs
(progs) Proofs made from the separate plates in colour process work, showing the sequence of printing and the result after each additional colour has been applied.
PTOT Phosphorous
Total amount of organic and inorganic phosphorous measured as Tot-P (phosphorous).