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Glossary of Printing Terminology

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Saddlestitching
Means of binding using wire for stitching.

Saturation
The attribute of colour perception that expresses the amount of departure from the neutral grey of the same lightness. Also referred to as intensity/chroma.

Scramble
see Hatching.

Screen
A screen is actually a fine film on to which is printed a very fine matrix. The matrix is then laid on to a photograph that is to be printed, and the combination of photograph and overlaid screen is then photographed again by a professional printing camera, producing a photograph of ‘dots’. These dots are then ultimately the position of printing ink, which reproduces a photographic effect. Screens are also used to print ‘apparent’ solid colours on forms but which are in fact a series or print dots that stimulate solid colours. Screen matrices can vary in fineness, and are referred to as dpi – pots per inch. The finer the screen, the better quality print production. Photographs in newspapers are examples of coarse screens – say 85 dpi. Good quality magazines will use 150 to 200 dpi and can go up to 400 dpi.

Screen Ruling
The number of lines per inch (or centimetre) on a halftone or tint screen, equal to the number of dots per inch on the printed image.

Scum
see Catch up

Secondary Colours
Colours produced by mixing pairs of the primary colours.

Self Adhesive Paper
Used essentially for labelling purposes, this grade has a self-adhesive coating on one side and a surface suitable for printing on the other. The adheshive is protected by a laminate that enables the sheet to be fed through printing machines, the laminate subsequently being stripped when the label is applied.

Self Cover
Used when the cover of a document is made from the same paper as its text pages.

Set off
The unwanted transfer of printing ink from a printed sheet to a surface facing it.

Sheeter
Machine that cuts reels of paper into sheets.

Sheetfed
Those presses or printers that run cut sheet paper rather then paper from a roll or web. Some sheetfed machines can be converted to run webs with the aid of in-line feeding equipment, which cuts the web as it feeds.

Short Grain
see Long grain

Show Through
Due to the low opacity of some papers, copy can be seen on the other side to which it was printed.

Shrink Wrap
Plastic film wrapping

Side Lay
A datum point on a printing machine for positioning correctly the side of the sheet in relation to the printed image; mechanism for moving the sheet to this point.

Side Perf
A perforated line running down the side of a continuous business form, usually 12 to 13mm in from each side of the form.

Signature
A print sheet that when folded and cut forms a group of pages. Also used to define a mark on the first and last pages of document when producing book blocks.

Silk
see smoothness.

Simplex
Single side printing.

Slitting
Dividing a web of paper in the length wise direction into two or more narrower webs, an operation often carried out by converters.

Smoothness 
The surface smoothness of paper is measured by the Bendtsen smoothness test. The test measures the amount of air escaping between an annular ring and the material surface, and results are measured in ml/min. Papers having a value higher than 50 are usually referred to as matt, below 50 as silk (sometimes called sating or velvet)

Soft Calendering
Soft calendars are more compact that other calendars and adopt a system whereby the web is passed between steel and hard rubber rolls. This method permits a wide variety of finishes between Silk and matt and the retention of bulk.

Soft Perf
An old fashioned type of perforated line, a method of production irrelevant to the form usage itself.

Soft Proof
A proof that, rather than being printed onto a substrate, is transmitted to a customer’s calibrated monitor and shown on a computer screen.

Solid Emissions
The bulk of the solids emitted in pulp and paper mill effluent are clay (used as a filler), calcium carbonate and wood fibres.

Solvent
The volatile liquid in which dyes and resins are dissolved and pigments are dispersed to produce printing inks.

Special Furnish
Papers made from special mixtures of pulps .

Spectrophotometer
Measurement device that determines colour value.

Splice
Joint of a web of paper in or approximately in the cross direction, made by an adhesive strip, either in order to obtain a reel of the desired length or to permit, (for example on a converting machine or roll fed press) a continuous operation between the end of one reel and the beginning of the next.

Spot Colour
Used to enable colours to be included in the print without mixing the primary colours.

Sprocket (hole)
The line of holes at each side of a continuous form to feed it through output printer devices.

Stereo
In flexographic printing, the flexible plate on which the relief image of one colour of a design has been produced. Normally made of rubber, stereos are sometimes called plates or stamps.

Stock
An aqueous suspension of papermaking raw materials from the stage of disintegration of the pulp to the formation of the web or sheet.

Strike Through
The effect seen on the back of a sheet of paper due to excess penetration of printing ink.

Stochastic Screening
Sometimes called FM (Frequency Modulated) screening. Improves the visual quality of print by breaking up the linear placements of dots using a frequency modulator to vary positioning, thus achieving random placement within relevant colour zones.

Strawboard
Originally a board made from straw pulp. Now used loosely to describe a number of boards, grey or yellowish in colour, used for stiffness in envelopes, pads, book binding and other purposes.

Substance
The weight of paper or board, shown by scale taken from a sample. The weight is defined by grammage per square meter of a single sheet (g/m squared).

Supercalendered (SC)
A surface finish on paper that may vary from relatively dull smooth to highly glazed, produced by passing damp paper through a supercalendar stack. This is broadly similar to a machine calendar stack except that it is separate from the papermachine and some of the rolls are made of compressed fibre (see also Calendered).

Surface Sizing
The application to the surface of the web, by means of a size press situated in the dryer section of the papermachine, of a suitable solution intended to improve the surface strength of the paper and resist penetration by oil based inks.

Subtractive Primaries
Cyan, magenta and yellow inks (dyes or pigments). Combined in the form of screened, over printing dots, they can create the illusion of other colours.

Sulphur Emissions
These cause acidification of soil and water, and are the biggest problem in making pulp by the sulphite method. Changing to the sulphate method and efficient flue gas scrubbing can significantly reduce sulphur emissions.

Sustainable Development
Keeping the overall environmental impact from operations within different areas of society within the limits of what man, society and nature can sustain in the long term.

SWOP (Specifications for Web Offset Publications)
A printing standard mainly for the US market. About to be aligned with the ISO 12647 standard.

Synthetic Paper
Paper produced by conventional means from furnishes comprising substantially or wholly synthetic fibres. Tcf (totally chlorine free) Pulp produced without any chlorine or chlorinated chemical compounds whatsoever.