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Animated Glossary

Printers have evolved a language of their own. This glossary helps you understand the professional terminology, acronyms and abbreviations.

Glossary

Bleed

Printing that runs off the edge of the page.

Blind embossed

A pattern stamped onto a sheet leaving a raised impression in the paper.

Brightness

Brightness is the amount of light a sheet of paper reflects. It is measured as a percentage; the greater the percentage the brighter the paper.

Bulk

Relative thickness of a sheet of paper.

Calendered

Paper that has been smoothed and polished between sets of rollers called a calender; this process is usually done at the dry end of a papermaking machine.

CMYK

Acronym for the process colours used in printing: cyan (C), magenta (M), yellow (Y) and black (K).

Coated paper

Paper coated with a clay coating provides a smooth printing surface and enhances the sharpness and gloss of the printed image. Coated paper is available with either a glossy, silk or a matt finish. For example the Hello range of papers.

Colour chart

swatch or book showing samples of colours with printing ink mixing formulas, e.g. the Pantone® Coated and Uncoated colour charts.

Colour control bar

Strip of coloured boxes on the edge of the sheet. It allows the printer to check the printing characteristics of every ink layer separately.

Colour correction

Adjusting the pixel colours in an image.

Colour separation

A full colour image separated into the four process colours (CMYK).

Colour transparency

A photograph on a transparent film.

Continuous-tone image

A normal photograph that has not been screened and therefore contains gradient tones.

Crease

To mechanically score a heavy paper or board to help folding and avoid cracking.

Cromalin ®

Accurate colour proof made by the printer for customer reference.

crop

The process of selecting only part of an image. Crop marks in the margins of a printed sheet show the correct position for finishing.

DCS

Desktop Colour Separation - an image file format that creates a postscript file for each CMYK layer and a PICT preview file.

Definition

The degree of detail, often termed as high and low definition.

Digital proofing

Proofs created directly from digital files and made on a digital printing system.

Dot grain

A printing problem where dots print larger than desired, creating darker tones or colour imbalances.

Dots Per Inch (DPI)

A reference for the resolution of a printed or screened image. Higher numbers mean higher resolution or more dots composing an image.

Dummy

A physical sample of a job made (often by hand) prior to production using the actual materials to show size, feel and binding. Can also include the visualised layout.

Duotone

Reproducing a black and white image in two colours, normally black and another colour.

Embossing

Stamping a sheet of paper to form a raised impression on the other side.

Finishing

All the stages that follow printing.

Foil stamping

The application of metallic or metallised images to a substrate by means of a heated relief block and controlled pressure.

Font

A set of type characters of the same design (and, with hot metal, same size); for example, upper and lower case, numerals, punctuation marks, etc.

Four colours process printing

A process, which uses black plus the three subtractive printing colours to reproduce all other intermediate, colours and shades. The four colours used are cyan (light blue), magenta, yellow and black.

Ghosting

Ghosting is seen when an image of the print on the reverse side of the sheet is visible on the side most recently printed.

Gloss

Gloss is the shine characteristic of a paper surface. It is measured by the surface reflectance value at a given angle.

Grain

In a sheet of paper, the direction along which most of the fibres are aligned. Grain direction can affect both printing and finishing performance.

Grammage

The weight of a sheet of paper, usually measured in grammes per square metre (gsm or g/m2).

Greyscale

A strip of standard grey tones ranging from white to black.

Gutter

The blank space or margin, from printing area to trim.

Highlight

The lightest part of an image in a halftone represented by the area with the smallest dots or no dots at all.

Hue

The main attribute of a colour that distinguishes it from another.

Ink drying

Ink is dry when it attains its final resistance properties. This can take a significant amount of time, depending on the paper, the ink used, and the atmospheric conditions.

Ink rub

An effect in which parts of a dried ink film are removed by pressure or friction onto another surface. It is often associated with silk or matt coated papers.

Ink setting

The initial drying phase of ink on a paper. At this stage the print can be handled without marking but is not fully dry and does not have its final resistance properties.

Insert

A piece of paper or card positioned between the leaves of a book and not secured in any way.

Laminate

A plastic film that is adhered to cover a printed sheet, either for protection or appearance.

Landscape (Oblong)

A book or printed sheet having its long sides at the head and foot.

Lithography

Also offset lithography - litho printing. Printing which uses a flat surface for transferring the image. A metal plate is treated so that water will adhere every place except where the image is located. Water is applied and then ink. The moist areas refuse to accept ink. Next this plate transfers its image to a rubber cylinder which finally transfers it to the paper. By contrast, letterpress printing uses a raised surface and gravure printing uses a sunken or depressed surface.

LPI

Lines per inch; a measurement of resolution.

Matt finish

A dull, clay coated paper without gloss or lustre. Matt papers have excellent readability characteristics due to low reflection.

Misregistration

One or more of the four passes (Cyan, Magenta, Yellow of Black) not completely aligned onto one another. This usually leaves a shadow or halo effect throughout the entire image.

Móire pattern

An undesirable pattern in colour printing, resulting from incorrect angles being used on overprinting colours or reproducing from an already printed subject.

Mottling

The formation of a visibly uneven ink film, most often in areas of solid colour.

Negative

Film containing an image in which the values of the original are reversed so that black areas appear white.

Offset

The most commonly used printing method, whereby the printed material does not receive the ink directly from the printing plate but from an intermediary cylinder. This ‘blanket’ cyclinder receives the ink from the plate and transfers it to the paper.

Opacity

Property of paper that minimises the "show-through" of printing from the back side or the next sheet. A paper with low opacity is more transparent.

Pantone (or PMS)

The colour system from Pantone Inc, that uses numbers to identify unique colours.

Picking

A lifting of the paper surface during printing. This occurs when pulling force (tack) of the ink is greater than the surface strength of the paper.

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 colours tend to be less vibrant but the result is more UV stable/lightfast. Pigmented ink is less coating dependent and dries quickly.

Pixel

A single dot on a computer display or in a digital image.

Positive

Film containing an image as per the original (the reverse of negative).

PPI

Pixels Per Inch - a measure of the density of scanned information in an image. The finer the optics of the scanner, the higher the scan resolution.

Process colours

The four process colour inks used in printing – cyan, magenta, yellow and black (also known as CMYK).

Progressive proofs

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.

Proof

A version of a document or colour illustration produced specifically for the purpose to review prior to reproduction.

Ream

Certain number of sheets of paper, wrapped in protecting paper.

Registration or register marks

Crosses or other marks used to make sure colours are aligned.

Resolution

The number of pixels per inch in an image or the number of dots per inch, used by an output device to measure sharpness

RGB

Red, green and blue are the three basic colours mixed to create all other colours on a computer screen.

Screen ruling

The number of dots per inch or cm. (Also known as screen frequency)

Seperation

Also colour separation. A separate film for each colour to be printed.

Set-off

The unwanted transfer of ink from a substrate to parts of the press or other parts of the substrate, etc.

Sharpen

The process of increasing the contrast at specific points in a photographic image where lighter and darker areas touch.

Sharpness

The ability to reproduce minute details of an original. The sharpness is related to the resolution of a photograph. The sharpness of a digital image can be manipulated artificially.

Silk finish

A clay coated paper with a subtle, silk-like shine. Because they reflect more light than Matt Finish (see glossary) papers, silk papers make images more eye-catching and still offer good readability for text.

Smoothness

Texture of the surface of paper. Also called its finish. Smoothness is 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.

Stiffness

The force required to bend a strip of paper or board through a known angle. Stiffer papers feel more rigid in the hand.

Varnish

A thin coating applied to a gloss, silk and matt sheet (often at the end of the printing press) for protection or appearance.

Whiteness

Whiteness relates to the entire visible spectrum. The higher the figure the greater the degree of whiteness.

Wire-o-binding

A series of wire loops pushed through punched slots along the binding side of a booklet.

Woodfree

Woodfree does not mean a paper is literally made without wood. It is a description of paper meaning that its wood fibres are chemically treated to remove the lignin (the substance that binds wood fibres together in the tree) making the paper product purer, whiter and stronger.