A film or paper manufactured by passing solid sheets of material between two polished rollers under high pressure. Mesh is also modified by this process. The rollers flatten the knuckles on one side to reduce Theoretical Ink Volume and hence film thickness.

A substance which has the capability of initiating or accelerating the speed of a reaction between two or more substances when introduced into their presence, normally in small quantities. It remains chemically unchanged at the end of the reaction.

The formation of a powdery coating on the surface of an ink film caused by disintegration of the binding medium due to disruptive factors during weathering.

A measure of saturation associated with colour.

Perceived as having a hue; not white, grey or black. Chromatic Attributes Those attributes associated with the spectral distribution of light.

That part of colour specification that does not involve illuminance. Chromaticity is two-dimensional and is specified by pairs of numbers such as dominant wavelength and purity.

The ratios of each of the three tristimulus values X, Y and Z in relation to the sum of the three: designated as x, y and z respectively. Sometimes referred to as the trichromatic coefficients.

A two-dimensional graph of the chromaticity co-ordinates, x as the abscissa and y as the ordinate, which shows the spectrum locus (chromaticity co-ordinates of monochromatic light, 380-770nm).

The portions of a signal that are dedicated to describing the hue and saturation. Used in measuring the difference between two colours of equal brightness.

A set of colour standards based on mathematical modelling of human vision and light. CIE colour spaces are used for the communication of colour independent of a specific device.

The ratios of each of the tristimulus values of a colour to the sum of the tristimulus values. In the CIE systems they are designated by x, y, and z.

A colour model to approximate human vision. The model consists of three variables: L* for luminosity, a* for one colour axis, and b* for the other colour axis.

A plot of the relative magnitude of the visual response as a function of wavelength from about 380 to 780 nm, adopted by CIE in 1924.

Known spectral data established by the CIE for four different types of light sources.
CIE Standard Observer A hypothetical observer having the tristimulus colour-mixture data recommended in 1931 by the CIE for a 2' field of vision. A supplementary observer for a larger 10' field was adopted in 1964.

The amounts of the three reference or matching stimuli required to give a match with the colour stimulus considered, in a given trichromatic system.

A two-dimensional graph of the chromaticity co-ordinates, x as the abscissa and y as the ordinate, which shows the spectrum locus (chromaticity co-ordinates of mono-chromatic light, 380-770nm).

Colour space in which values L*, u*, and v* are plotted at right angles to one another to form a three-dimensional co-ordinate system. Equal distances in the space approximately represent equal colour differences.

A defect in which a wet ink or varnish recedes from small areas of the surface leaving either no coating or an attenuated one. (See reticulation).

Used in pad printing. The "inkable" steel or nylon plate that is etched with an image to be transferred on to the silicone pad and then to the part.

Premature drying of ink in the screen, causing bad print by blocking part of the open stencil.

Of the Society of Dyes and Colourists in Great Britain. Developed a more logical, ellipse-based equation for computing DE values as an alternative to the rectangular co-ordinates of the CIE LAB colour space.

A system to measure and control the process colours that are used in four-colour printed reproduction. See Colour Management System.

Three subtractive primary colours used in colour-negative printing, and some colour-output devices, to produce a full gamut of colour. The combination of pure CMY inks produces black, and the elimination of all three produces white.

Cyan, Magenta, Yellow, and Black (or Key) are the four colours used in process-colour printing. Also known as subtractive colour, the colour black is achieved by the presence of all inks.

A printing paper having a transparent, smooth layer added to one or both sides that changes the look of the final printing. Coatings are normally defined as hard glossy, semi-glossy or matte surfaces.

Fine filaments produced by the ink between the pad and the substrate being printed, culminating in a cobweb-like appearance on the finished print. It may be reduced to a minimum by careful selection of solvents and proper adjustment of printing conditions, and reduction of static charge.

The forces which bind the particles of ink or varnish film together. It is distinct from "adhesion", the forces binding the film to its substrate.

The process of curing at normal atmospheric temperature.

1) The subjective appearance of the printed ink. Note that this definition embraces all colours and black and white. 2) Synonym for ink.

A three-dimensional characteristic of the appearance of an object. One dimension usually defines the lightness, the other two together define the chromaticity.

A series of ink patches printed on a press sheet that may include solids of cyan, magenta, yellow, black, and spot colour ink; 25%, 50%, and 75% tints of those colours; and two-colour overprints using those colours.

A system of software and/or hardware that adjusts and co-ordinates colours between two or more digital devices. Colour calibration systems commonly compare device colour profiles and translate one colour model into a device-independent language.

Shrinking the colour gamut of the original to the colour gamut a printing process will represent.

A graphic mechanism for displaying colour measurements and for making colour changes to an image. User adjustments to the angle and slope of the curve implement colour changes to one or all of an images colour channels.

Magnitude and character of the difference between two colours under specified conditions.

A range of colours that can be reproduced by a given system.

A combination of software and or hardware devices used to produce accurate colour results throughout a digital-imaging system.

Inks are said to match in colour if, under specified conditions of illumination and viewing, no significant difference in their hue, saturation and lightness can be detected.

Relative amounts of three additive primaries required to match each wavelength of light. The term is generally used to refer to the CIE Standard Observer colour matching functions.

A colour measurement scale or system that numerically specifies the perceived attributes of colour.

A colour sample that attempts to represent the final printed image that will result when a piece is offset printed. Colour proofs can be generated from film separations prior to using the separations to make printing plates. Common types are Cromalin, MatchPrint, ink jet, dye sublimation, laser copies, or photographic film or paper.

Colour stability after exposure to the elements.

Colour Strength. A measure of colour purity or dilution by a neutral.

The process of separating a colour image into four subtractive colours, CMYK, either by photographic or electronic processes, thus producing a set of four films or a computer file.

Three-dimensional mathematical model enclosing all possible colours. The dimensions may be described in various geometries giving rise to various spacings.

Tristimulus values, chromaticity co-ordinates and luminance value, or other colour-scale values, used to designate a colour numerically in a specified colour system.

A concept that relates colours for description or reproduction. Models in imaging include CIE, PMS and Photo YCC, among others.

The colour spectrum of a "black body" radiator heated to a given temperature on the Kelvin scale. The manufacturer's method of indicating the colour of a light source in degrees Kelvin (K); i.e. 2700K (yellow/white), 4100K (white), 5500K (blue/white).

A photographic or line-art image printed in colour on clear film. A film positive.

The visible spectrums continuum of colours arranged into a circle, where complementary colours such as red and cyan are located directly across from each other.

Materials used to create colours-dyes, pigments, toners, and waxes.

A device for measuring colour values; an optical measurement instrument that responds to colour in a manner similar to the human eye by filtering reflected light into its dominant regions of red, green, and blue.

Of, or relating to, values giving the amounts of three coloured lights or receptors-red, green, and blue.

See pigmented.

The mathematical relationships that assign a weight to red, green, and blue colour separations to reproduce the original colour. 3-by-3 matrixing is the use of a colour-matching function available on some scanners. See also 3-by-3 matrixing.

Liquid having a flash point at or above 100 degrees Fahrenheit (37.8 degrees C) but less than 200 degrees Fahrenheit (93.3 degrees C).

Two or more inks or varnishes which can be mixed without producing any undesirable effects, such as precipitation, belling, coagulation, are said to be compatible.

Two colours that, when combined, create neutral grey. On a colour wheel complements are directly opposite the axis from each other; blue/yellow, red/green, and so on.

System used to generate and reproduce full-colour designs, artwork, photographs, etc., through use of a computer, plotter, printer, etc.

Generally describes any programmable, computerised, motor-driven system of components that functions in a manufacturing capacity.

The apparent viscosity of an ink or varnish when shearing forces of varying degrees are applied to it in various ways, e.g. when it is disturbed in the can, poured from one vessel into another, or printed.

A highly reflective film rendered in bright safety colours to enhance appearance under highway conditions.

A photographic image containing gradient tones. For printing purposes, continuous-tone images are converted to dot patterns (halftones).

The difference between the dark and light areas of an image. The lower the number value, the more closely the shades will resemble each other. The higher the number, the more the shades will stand out from each other. Speed of density change; graduation.

In computer imaging, to change a CMYK file to RGB, Photo YCC, or vice versa, or to convert one file format to another.

A polymer of two or more different monomers.

An electrical surface treatment that encourages oxidation through ionisation of a surface to reduce surface tension and improve ink adhesion.

The area covered by one unit weight or unit volume of thinned ink under defined printing conditions.

Specifically, a breakdown in which the cracks penetrate at least one coat and which may be expected to result ultimately in complete failure.

Undesirable depressions in the dried ink film that may be large enough to expose the substrate.

The cohesive effect of ink into drops after printing onto a surface which the ink does not wet completely.

A "spider-web" cracking of paints or plastic, caused by weathering, cleaning with strong solvents, or the use of improper paints.

The spontaneous spreading of liquid on the surface. In the case of an applied film of ink or varnish, it refers to the spread of the wet film beyond the area on which it was applied.

Image rub-off that occurs when a pigment or dye is not adequately fixed in the substrate.

To remove part of an image.

The process of condensation of polymerisation of a material by heat or chemical means, resulting in the full development of intended properties.

An addition which promotes the curing of a film.

A vector-driven device (similar to CAS plotters) for cutting sign-making substrates. Recent designs include digital-print (inkjet) systems combined with cutting-plotter systems. (See also, Plotter and Printer/cutter.)

One of the three subtractive primary colours. Produced by mixing equal amounts of blue and green projected light. Cyan is also one of the four colours used in four-colour printing.

German National Standard.

Dots per inch. A measure of the detail of a print. "Apparent d.p.i." refers to the fact that the eye perceives an image as having greater detail than in does in physical reality.

The CIE Standard Illuminant that represents a colour temperature of 6504_K. This is the colour temperature that is most widely used in graphic arts industry viewing booths. See Kelvin (K).

CIE Series of spectral power distribution curves based on measurements of natural daylight and recommended by the CIE in 1965. Values are defined for the wavelength region 300 to 830nm.

Small graphics, long or short-term, printed on adhesive-coated vinyls or transfer materials.

See "Transfers". (In the USA the term "Decals" also embraces printed self-adhesive plastics).

Removing dirt and oils from the stretched screen before applying the stencil to insure adhesion to the screen surface.

An instrument that measures transmitted or reflected light. It will indicate, in density units or percentage dot, the percentage of a given area that is covered by halftone dots. This instrument is used to ensure consistency and process control.

The distance in front of, and behind, the subject that will be acceptably sharp. This distance will increase as the lens aperture is reduced.

A photosensitive chemical added to emulsion used in making screens (stencil).

A glass plate coated with a number of thin layers of material that will reflect all but one very specific colour. Also called dichroic mirror.

Cutting of material to a specific shape using dies.

The translucent-white sheet that evens out the light coming from the lamps in an optical system.

Image and line data that has been translated into numerical values for manipulation and reproduction.

Portable optical recorder that captures images on an internal memory chip, removable PC cards, or other digital media. Images can be transferred electronically to a computer for manipulation, e-mailing or website creation.

One of several non-impact technologies where the image is formed by a computer controlled printer. (Generally accepted to include: electrostatic, ink jet, laser photo, and thermal transfer.)

The process of obtaining various tones by breaking up the image into a graduated series of dots. The dots repeat in a regular pattern, creating the illusion of continuous tone. The digital printing process is controlled by the size and shape of dots.

The process of image capture, manipulation and final image form, accomplished by electronic systems.

Internegs that are produced by digitally scanning the original transparency to create a digital file, then imaging the digital data using a film recorder to record the image onto a negative film stock.

Any printing device that is capable of translating digital data into hardcopy output.

Microprocessor chips specially designed to convert, modify and manipulate streams of digitised signals in real time. These chips allow for faster telephony, faxing, and audio and video capture and editing.

A means of authenticating electronic documents. A digital signature is actually a special kind of encrypted message needed for electronic commerce.

The process of converting analogue data to digital information.

A volatile liquid which, while not necessarily a solvent for the non-volatile constituents of an ink, may yet be used in conjunction with the true solvent without causing precipitation.

The ability to resist dimensional change; i.e. the amount of shrinkage or expansion.

A liquid photo-polymer emulsion used as a screen printing stencil which is coated onto a stretched screen, dried, exposed through a film positive to actinic and developed.

Signs lit from the outside with floods, spots, etc.

A method of exposing a screen printing stencil that uses a small format (typically A4) photopositive to produce a large image (typically 8 feet by 4 feet)

Imaging techniques that allow for the elimination of film separations from the printing process. These systems utilise a computer controlled system employing digital printing heads to "write" digital data to a coated screen that is then mounted on the press.

The breaking up of a particle aggregate into separate particles without changing the particle size.

Highest level of density.

Lowest level of density.

Rigid or flexible steel blade used to remove excess from printing Plate. Also called blade, wiper, squeegee.

Dots make up an image in colour separations or halftones. Halftone dots will have a fixed density but have variable size (amplitude modulation).

Percentage of paper covered by ink dots of a given colour. See Apparent Dot Area.

The phenomenon that occurs when ink expands its coverage during printing onto a substrate; often caused by abnormal or excessive absorption by the substrate or low viscosity inks.

The distance between the dots on a computer monitor, typically 0.24 to 0.38 mm. The closer the dots the sharper the image on the monitor.

A linear measurement of resolution used for scanning and printing. Generally, more dots per inch mean a higher resolution, a greater amount of visible detail in the image, and a larger file size.

The resolution of an image or how many pixels are defined in the boundary of an inch. The more correct term is pixels per inch, however dots per inch is often used instead. This more correct in the case of electronic files.

The shadowing effect on letters, to simulate light being cast at an angle.

A type of optical scanner where the reflective or transmissive art is mounted to a rotating drum. As the drum spins, light from the image enters a lens allowing the image to be recorded in a series of fine lines.

A machine for drying wet prints.

Acronym for desktop publishing, including typesetting, image handling and page composition.

See "Two Pack".

A monochromatic printed image created by two overlapping halftone screens of different colours; generally created from a black and white photographic original in order to add additional tonal range, or to create a tinted or coloured appearance.

To print on both sides of a single page.

A relative term used to describe the functional life span of a material or ink typically compared to a control.

A technology similar to Compact Disc, but far superior in its storage capacity. A DVD can contain about 4.7 GB of data in its single-sided, single-density version, and 18 GB or more in a double-sided, double-density version.

An imaging process that vaporises colorant with heat and pressure, and deposits it on to a substrate in order to simulate a continuous tone image.

Organic colouring substances. Pigment dyestuffs are virtually insoluble in water and in the usual ink and varnish vehicles. Some dyes are soluble in water and organic solvent and are classed according to their solubilities. A soluble colorant; as opposed to pigment, which is insoluble.

The measurable difference between the brightest highlight and the darkest value.