Mar 10 2010

Glossary of Terms for
Paper and Printing

"P"

PAGINATION

Page numbering.

PALLET

A wooden platform with a slatted bottom used to hold and ship stacked cartons of paper.

PAMS

A grade of waste paper, mostly used or unused magazines.

PANTONE MATCHING SYSTEM®

Widely-used system of colour matching on Coated and Uncoated stock, also known as PMS. Based on a colour swatchbook system that gives printers recipes for how to mix inks to match the colours shown, Pantone is the most widely used ink colour matching system in America.

PAPER

A matted web of cellulose fibres 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 GRADES

Paper is classified into different grades according to the end use, the pulp used and the treatment of the paper:

- Paper made by a slowly rotating machine called a cylinder mould that simulates the hand-papermaking process. Fibres become more randomly intertwined than in machinemade papers, producing a stronger, more flexible sheet or roll.
- Paper made by hand using a mould (a frame covered with a flat, rigid screen or flexible screen). In both cases the mould is covered by a flat frame called a deckle, to contain the run-off of wet pulp, dipped into a vat of wet pulp, shaken to distribute the fibres evenly and drained of its excess water. The wet mat of fibres remaining in the newly formed sheet is then dried against blankets & may be hot pressed, cold pressed, or air dried.
- Paper made on a very rapid running machine called a Fourdrinier, producing consistent quantities of sheets or rolls.

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 fibres and to dissolve lignin, then washed to remove impurities. Most printing papers are then bleached to lighten the colour 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 fibre 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.

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.

PARCHMENT

A hard finished paper that emulates animal skin; used for documents, such as awards, that require writing by hand.

PASSWORD

A secret alphabetic, numeric, or alphanumeric code when combined with a user name allows a user access to the site as a buyer, seller, or mill.

PCW (Post Consumer Waste)

Percentage of fibre used in the process of making paper that has been previously used.

PDF

Portable Document File. A cross platform format for moving documents between Apple Mac and PC.

PEFC

Pan-European Forest Certification Scheme. A scheme for auditing forestry operations, taking into account the effects on the environment.

PERFECT BINDING

Single sheet papers are stacked and glued together along one edge and wrapped with a cover.
Perfect binding: A stack of single sheet papers are glued together along one edge and wrapped with a cover sheet.

PERFECTING PRESS

A press that prints both sides of a sheet at the same time.

PERFORATING

Piercing a series of holes into a sheet of paper, primarily to enable tearing.

PETROLEUM-BASED INKS

Inks that use petroleum as the vehicle for carrying the pigr/m2ent. 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. A paper with a pH over 7.0 is considered acid free, or alkaline and a sheet below 7.0 is considered acidic.

pH VALUE

A measure of the active acidity or alkalinity of a solution. A value of 7.0 is neutral.

PHOTO GRAVURE

A method of printing by an engraving process. See Intaglio.

PICK OUT

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 fibres and transfers them onto the printing blanket, creating "hickeys" (printing blemishes) on subsequent sheets.

PICK RESISTANT

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

PICKING

The problem of ink picking off paper fibres during printing. This may be an indication of a paper with low bonding strength or the use of an ink with too much tack for the paper it is printed on.

PIEZO

A type of printing where ink delivery is controlled by a piezo crystal which flexes when an electrical charge is applied to it, this distortion can be varied with the charge, thereby regulating the amount of ink ejected. Print speed tends to be slow. Print head nozzles need to be kept clear as clogging disrupts image.

PIGMENT

An ingredient added to pulp to increase the brightness and opacity of white paper. Pigment dyes are also used in some coloured grades to create deep colours.

PIGMENTED INK

Becoming more popular, this ink\\\'s pigment can be dispersed in oil/solvent or water, with a larger particle size than for dye inks. Output colour tend to be less vibrant but the result is more UV stable/lightfast. Dry times are fast and this ink is less coating dependent.

PILING

In printing, the build up or cracking of ink on rollers, plate or blanket; will not transfer readily. Also the accumulation of paper coating on the blanket of an offset press.

PIN HOLES

1. Small holes in paper caused by fine particles of sand, etc. When paper is calendered, the particles are crushed and fall out leaving a hole. 2. Small holes in thin paper due to fibres being drawn through the mesh of the wire by excessive suction.

PIXEL

A single picture element, the smallest unit of information in a scanner or monitor.

PIXELISATION

When bitmapped type or graphics are scaled, individual pixels in a character are enlarged to the point where they become objectionable resulting in jaggies. Also referred to as aliasing.

PLANOGRAPGY

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.

PLATE FINISH

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

PLY

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

PLY

A single sheet in laminated paper.

POCKET (ENVELOPE)

An envelope with its opening flap on the short edge.

POINT

A measurement unit equal to 1/72 of an inch. 12 points to a pica, 72 points to an inch (Imperial).

POROSITY

The looseness or tightness of paper fibres is measured by the ability of air to permeate the sheet, an important factor in ink penetration.

POROSITY

The degree of a paper's openness, measured by its resistance to wind

POST-CONSUMER RECYCLED PAPER

Recycled paper made from waste paper materials recovered after use by consumers.

POSTSCRIPT

A standard page description language for graphics and publishing.

PPI

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

PPI

Pixels Per Inch. A measure of resolution.

PRE-CONSUMER RECYCLED PAPER

Paper recovered after the papermaking process but before use by a consumer.

PRECISION SHEETING

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

PREMIUM

Any paper that is considered better than No.1 by its manufacturer.

PRESS PROOF

A printing test of the actual job before the final production run. 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.

PRESSING

The process of squeezing the water out of newly formed paper sheets.

PRINT QUALITY

The quality of the finished printed piece, which is affected by the paper, ink press and skill of the press operators.

PRINTABILITY

The overall performance of the paper on press.

PRINTER

Any individual or company that creates printed material by applying ink to paper using a printing press.

PRINTING

The transfer of ink onto paper or other materials to reproduce words and images.

PRINTINGS

A term applied comprehensively to the many varieties of papers used for printing purposes.

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 COLOURS

As four colour process printing, The three primary colours used in process printing (cyan, magenta and yellow) plus black.

PRODUCT SPECIFICATIONS

The parameters of a product being purchased or inquired about.

PROFILE

A graph showing the variations in grammage moisture content or other property from point to point on paper web, either across or along the ma-chine direction.

PROOF

A copy made before the full job is run, in order to check quality and accuracy of origination and specification.

Pt.

The abbreviation of point, a measurement of the thickness of paper.

PULP

A slurry of cellulose fibres and water which is the basic ingredient for paper.

PULP (CHEMICAL)

Pulp obtained through the elimination of a large proportion of non-cellulose matter through a chemical treatment (ex. through boiling).

PULP (MECHANICAL)

Pulp obtained from various raw materials, essentially from wood, entirely through mechanical means.

PULP (SEMI-CHEMICAL)

Pulp obtained when eliminating the non-cellulose components from the raw material by means of a chemical treatment.

PULP SUBSTITUTES

Unprinted, clean waste paper that can be used directly in paper making as a substitute for wood pulp.

PULPING WOOD

To separate cellulose fibre from lignin, tree logs are chipped and processed into pulp either by mechanical or chemical means.

PVA (Polyvinylacetate)

Polyvinyl acetate glue. One of the most popular modern adhesives used in printing and bindery.