Jul 31 2010

Glossary of Terms for
Paper and Printing

"S"

SADDLE-STITCHED BINDING

Folded sheets or signatures of paper are gathered together, one inside the other, and placed over a "saddle," then stitched or stapled along the spine with wire.

SALLE

The department of the paper mill, sometimes called the Finishing House, where paper is sorted and counted.

SATIN FINISH

A smooth, delicately embossed finished paper with sheen. Also called Silk.

SBS (Solid Bleached Sulphate)

A type of heavyweight board that is a single thickness run on a Fourdrinier paper machine using sulphate produced pulp.

SCORING

The process of pressing a groove into the paper to allow it to fold more easily and keep the sheet from cracking when folded. The score should run parallel to the paper grain and be folded with the scored side on the outside. Thick papers require wider scores.

SCREEN

In offset lithography, a screen is a glass or film with cross-ruled opaque lines or vignetted dots used to reproduce continuous tone artwork such as photographs.

To create a halftone, an image is shot through the mesh screen to break it into tiny dots. The closer the line screen, the smaller the dots and the more dots per inch and, hence, the finer and crisper the printed image.

Less absorbent papers reduce the spread of ink dots and, therefore, a finer line screen can be used.

SCREEN ANGLES

Technique used in 4-colour printing which sets halftone screens at various angles to avoid moiré patterns.

SCROLLS

Long sheets of paper, papyrus or parchment that can be rolled for storage.

SECONDARY FIBRE

Fibre that has been used before, e.g. waste paper.

SECURITY PAPER

Generally rag paper, always woodfree, watermarked and chemically impregnated. Very reactive and strong. Security papers also carry identification marks which help to prevent counterfeiting. Used for making bank notes, cheques etc.

SELF COVER

A booklet covered with the same paper that is used for the inside text pages.

SET-OFF

The unintentional transfer of wet ink from one sheet to another, usually due to the sheets being stacked too high or moved before properly dry.

SHADE

The hue and depth of a particular colour within the same colour family - such as, the many shades of red.

SHEET-FED PRESS

A press that prints single cut sheets of paper, rather than a continuous roll or web of paper. Because sheet-fed presses print one page at a time, they are better suited for shorter runs.

SHEETWISE

Also called work-and-back, this is a method of printing different pages - or two different forms - on the front and back sides of a large sheet of paper.

SHEFFIELD

A test to measure the smoothness of paper by measuring the rate of air flow over the surface of the sheet.

SHOW-THROUGH

The undesirable condition in which the printing on the reverse side of a sheet can be seen through the sheet under normal lighting conditions. The more opaque a sheet, the less the show through.

SIDE STITCH

To staple sheets or signatures on the side closest to the spine.

SIGNATURE

The term used for a large printed sheet or form after it has been folded and trimmed down to page size.

SILK FINISH

See Satin Finish.

SILK SCREEN

Also known as screen printing, this printing method forces ink through a porous screen, such as nylon, directly onto the paper or other material. An emulsion or stencil is used to block out the non-printing areas of the screen so that only type or image appears.

SIZE

Non-fibrous materials used in papermaking to control the absorbency of paper. Rosin, Alum, starch and gelatine are the most commonly used.

SIZE PRESS

Section of paper machine where surface treatments are applied to the sheet of paper to give it special qualities. Normally comprised of a pair of rolls towards the end of the dryer train between which the dry or partially dry web is passed, and into the nip of which a liquid, usually starch, is applied to impart strength to the sheet. Sometimes a chemical may be added to produce a water-resistant sheet.

SIZING

The property of paper that relates to its resistance to water, other liquids or vapours. Sizing ingredients are added to pulp before it is formed into paper or applied to the surface of the paper after it has dried. Sizing serves as a glue to keep the paper fibres tightly woven and in place so the sheet won't pick on press.

SKID

A wooden platform used to stack papers that are not packed in cartons.

SLURRY

The mixture of pulp and water that is poured onto the forming wire of the papermaking machine. Slurry is 99% water.

SMOOTH FINISH

Text and cover grades that are highly calendered are called smooth finish papers. A smooth finish creates a hard, uniform surface that provides strong ink holdout and crisp dot resolution.

SMOOTHNESS

Texture of the surface of paper. Also called its finish. Generally determined with a tester which measures time required for a given volume of air to flow between the surfaces of the paper sample and a piece of optically-flat glass under standard loading conditions.

SO2

Sulphur Dioxide. Formed during the combustion of fuels containing sulphur (such as oil and coal). Sulphur dioxide contributes to the acidification of soil and water.

SOFTWOOD PULP

Pulp made from coniferous trees such as pine and fir. Typically paper is made from a blend of softwood and hardwood pulp. Softwoods provide long fibres for strength, and hardwoods have shorter fibres that contribute to smoothness and bulk.

SOLID WHITE BOARD

Board made of one or more plies of bleached chemical pulp.

SPECIFYING PAPER

The process of choosing the right paper for a specific printing job. Designers and printers typically base this on individual design, printing, handling and budget requirements.

SPOT COLOUR

A solid colour, such as those specified by Pantone colour System; the opposite of a process colour.

SPOT VARNISH

UV varnish applied to a specific area of the printed sheet.

STABILITY

The quality of paper to maintain its original size when it undergoes pressure and moisture changes.

STARCH

Material used as a surface or internal additive to provide strength.

STATIC

Electricity generated by friction as paper comes into contact on press with other paper, metal, wood, etc; the result of insufficient moisture in paper. Static causes the sheets to be attracted to each other, causing feeding and jogging problems.

STENCIL

A sheet of plastic, cardboard, metal or paper in which a desired letter or design has been cut out so that ink or paint applied to the sheet will reproduce on the surface beneath.

STIFFNESS

Rigidity, resistance to bending and inflexibility.

STOCHASTIC

A method for creating halftones, stochastic screening uses frequency modulation (FM) to generate randomly placed dots. Holding registration on press is harder with stochastic screens, but the resulting colour is often richer.

STOCK

In papermaking, refers to the wet pulp before it is fed on to a papermaking machine, or during the papermaking processes before it becomes a sheet of paper; contains around 99% water and 1% fibre. In graphic arts, stock means "paper" or board that will be printed, or finished.

STOCK, STUFF, PORRIDGE

Terms used to describe the papermaking material in all stages, but usually referring to the wet pulp before it is fed onto the paper machine.

STRETCH

The "give" of a sheet of paper as it undergoes tensile pressure.

SUBSTRATE

The material (usually paper, plastic or metal) upon which an image is reproduced.

SUCTION BOXES

Devices situated under a part of the wire which withdraw water and air from the rapidly consolidating web, also used in felt cleaning etc.

SUGAR PAPER

A quality wrapping paper, blue or purple, principally from waste paper and formerly used for sugar bags.

SULPHITE

Sulphite pulp is produced from the wood of coniferous trees. Wood chips are cooked in calcium bisulphate or sodium sulphite, and bleached, producing fairly long strong fibres. Since the end of the 1860's until recent years, it has been the most widely used pulp in America. In fact, the term "sulphite" has become generic and is still accurately used to describe any paper made from wood in distinction from papers made from cotton or other fibres. Sulphite pulp is available in a range of grades up to pure alpha cellulose.

SULPHITE PULP

Paper pulp from wood chips and pressure-cooked in a solution of caustic soda and sodium sulphide. Also known as kraft.

Sulphite pulp is produced from the wood of coniferous trees. Wood chips are cooked in calcium bisulphate or sodium sulphite, and bleached, producing fairly long strong fibres. Since the end of the 1860's until recent years, it has been the most widely used pulp in America. In fact, the term 'sulphite' has become generic and is still accurately used to describe any paper made from wood in distinction from papers made from cotton or other fibres.

Sulphite pulp is available in a range of grades up to pure alpha cellulose.

SUPERCALENDAR

Machine for giving paper a very smooth surface by passing it through a series of alternate metal and composition rolls, revolving with high speed and pressure.

SUSTAINABLE DEVELOPMENT

Development which meets the needs of the present without compromising the ability of future generations to meet their own needs.

SWATCHBOOK

A booklet containing paper samples and specifications for each grade of paper.