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O

OFFSET PAPER  Paper which is uncoated or coated and strong enough to resist the pull of tacky inks used in offset lithography.

OPACITY Ability of a substance to prevent light from passing through it. Also a term used for paper on which Bar Codes are printed.

P

PAPER GRAIN Predominant alignment of fibres corresponding to direction in which paper flows on wire screen of papermaking machine.

PAPER SMOOTHNESS Paper resistence to air flow, used as a measure.

PAPERWEIGHT: Weight of paper which is measured in grams per square metre. [GSM/gm2] e.g. 60 gsm usually used for single part listing paper.

PASTE BOARD Paper board made of two or more papers or boards laminated together

PERFORATION TEAR STRENGTH Tear strength of perforated paper, measured perpendicular to perforation and related to combination of perforation pattern and type of paper. Expressed in weight per unit area.

POROSITY Characteristic of being permeable to liquids.

PORTRAIT Orientation of sheet of paper i.e. narrow edge or A4 at top and bottom is termed portrait, long edge of A4 at top and bottom is termed landscape.

PRINTABILITY Characteristics of paper to ensure good quality print.

PULP BOARD Board manufactured on a Fourdrinier machine or special cylinder machine by a similar method used to manufacture paper. 

PULP CLASSIFICATION Classification of uncoated papers according to furnish. i.e. DIN 827 Specification for Pulp Classification.

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R

RAG PAPER Cotten fibre content paper.

REAM Quantity of 500 sheets of paper.

RECYCLED PAPER Paper produced from waste paper. Fibres are never as good as when originally used. 

RECYCLED PAPER GRADES Percentage of post consumer, de-inked waste paper combined with pulp stock made from virgin fibre to ensure good runability characteristics.

REGISTER BOND Grade of writing and printing paper. [Form Bond]

RELATIVE HUMIDITY Moisture of the surrounding air and any packaging materials which affects dimensional stability of paper.