Glossary of Terms

The Technical Dictionary

A
Abrasion resistance of ink Is typically testet by using a fine sand paper while applying a head force of 4 Newton on the sand paper and doing 200 grinding movements forwards and backwards on top of the printed image.

Absorbing materials Paper, carton are absorbing materials. Plastics are non-absorbing materials.

Adast printing presses A manufacturer of printing presses located in the Czech Republic.

Adhesion of ink Describes the level of intermolecular binding forces between ink and plastic material. In the card printing industry, it is tested by an adhesive tape which will be sticked on the print and then peeled off rapidly. The ink will remain on top of the card surface when the quality is ok.

Anilox technology Describes the ink transfer from the ink casstte into the roller system via an anilox roller which shows laser engraved nips of a constant nip depth and diameter on its surface. Excess of ink on the anilox roller surface by rotating through the ink is wiped off by a blade. The advantage is a constant ink quantity transfer, the disadvantage is the unflexibility when more or less ink will be needed during the printing process.

Anti-static bar Reduces the electrostatic and dyne level on plastic surfaces which improves the transport through the machine and the adhesion of ink on the plastic substrate.

Anti-toning agent Consists of silicone oil and reduces the scumming effects of the inks. Recommended quantity to be mixed into the inks up to max. 5%

Anti-tack paste (=reducer) Reduces the ink viscosity in order to improve printability of the ink. Usually can be added up to 5% to the ink. Note that too much reducer used in waterless offset will result in scumming.

B
Bleed This is the area that extends outside the trim marks

Blue key A blue translucent film used for very critical patching work

Bond paper Good quality papers used for stationery, forms and other documents having a basic weight of more that 60 grams per metre square; often containing a watermark.

Binding agent In waterless inks it binds pigments and photo-initiators together and determines mainly the ink viscosity.

Blanket In offset printing, a rubber-surfaced fabric clamped around the cylinder which transfers the image from plate to paper.( …see our product list )

Blanket cylinder The cylinder on which the blanket is fixed. The blanket overtakes the image from the printing plate and transfers the image onto the substrate.

C
Cast coated Coated paper, dried under pressure against a polished cylinder to produce a high gloss finish.

Conti-Air A german manufacturer of blankets for the printing industry.

Continuous tone image A photographic image which has not been screened and contains gradient tones, eg. a normal photograph.

Card materials Typical card materials are ABS, PVC, PET, PC, carton.(…see our product list )

Cartridge paper A strong, stable compressed paper with natural, uncoated surface.

Catching-up In lithography a term which indicates that the non-image areas of a press plate are starting to take ink or scum.

Chip cavity A cavity considered in the card according to chip or microprocessor shape and dimension.

CMYK The four process colours used in offset printing: cyan, magenta, yellow and black.

Coated paper Paper with a surface coating which produces a smooth, glossy finish.

Coating In plate making: the light-sensitive mixture applied to a metal plate. In printing: an emulsion, varnish or lacquer applied over a printed surface to give added protection or gloss.

Cold colour In terms of printing, a colour which is on the blueish side.

Colour correction Changing the colours of pixels in an image to achieve the desired effect.

Contrast The difference between the lightest and darkest areas of an image.

Cooling system for offset presses In modern sheet offset presses there are watercooled vibration rollers and plate cylinders to avoid scumming. Depending on heat transmission of the press and the used inks it is recommendable to adjust water temperature in a range of 20 – 28 °C ( 68 – 82 °F ). It is also possible to use chilled air which blows on the printing plate .

Corona treatment Improves dramatically the dyne level of plastic sheet/card surfaces and consequently the ahesion of inks on the plastic substrate. This process should be integrated into the press to take the max. advantage. The effect of corona treatment is reversible and remains effective a few days.

Cromalin Actual colour proof for customer´s and printer´s reference.

D
Density range The range from the smallest highlight dot to the largest shadow dot.

Die-stamping A printing process using an engraved, intaglio (depressed) image and producing an embossed, relief effect on the substrate.

Digital proofing Producing page proofs directly from stored digital information without film or plates, eg. laser, inkjet, thermal transfer dye sublimation or ink-jet systems.

Dummy A model of the printed product produced prior to publication to show, as far as possible, the size, shape and major features as a guide to production.

Duotone The reproduction of a black and white picture in two colours, normally black and another colour. One colour tends to stress the highlight areas and the other the shadow.

Density of ink The ability of an object to stop or absorb light. The less the light is reflected, the higher its density, eg a solid black area on film reflects no light and therefore has 100% density.
Standard densitometer values of CYMK in Offset printing are:

Yellow : 0.8 – 1.0
Cyan : 1.4 – 1.5
Magenta: 1.4 – 1.5
Black : 1.7 – 1.9

Densitometer An instrument used to measure the density of a given area or screen, eg. 50%

Die-cutting The use of sharp steel rules to cut special shapes from printed sheets.

Dot gain Is the difference of original dot size on the film/plate and the real printed dot on the sheet/card. Wet-offset on absorbing materials shows higher dot gain than waterless offset. Non-absorbing materials like PVC show even better results. Moreover, dot gain can happen if the pressure of the blanket to the substrate is too high. (… see more details )

Double sheet control system Control device to make sure that only one sheet/card at a time enters the printing press in order to avoid a damage of the blanket.

Duplicating Describes a printing error and shows often double lines around shape or edge lines. Reason is very often a too high pressure between printing plate and blanket.

Dyne level of plastic cards Is an attribute which mainly determines the adhesion of the ink on the plastic surface. It is measured in mN/m and acceptable levels are 38 mN/m or higher in order to obtain a good adhesion of ink. It can be checked with test-pens prior to printing.

E
Embossing Where paper or board is compressed by means of a die to forma raised image on the material.

Emulsion The photosensitive layer on a piece of film, paper or plate onto which an image can be exposed.

Elliptical dot A type of halftone dot with an elliptical rather than circular shape, which sometimes produces better tonal values.

F
Font The complete assortment of type of one size and face.

Feeder Stacks the unprinted cards/sheets in the printing press.

Film negative type A piece of film with an image in which dark areas appear transparent and light areas appear solid.

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

Form roller Transfers the ink to the printing plate. In modern offset presses there are 4 and more form rollers installed.

G
Gradient fill A fill that displays a gradual transition from the foreground to the background colour.

Gripper edge The leading edge of paper as it passes through a printing press.

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

Ghosting Describes a printing error when a part of an image reappears as a shadow at a place on the sheet/card where it should not be. Mostly, this happens in images where there are white areas within a solid (100%) print area. A well working solution is to change the settings of the vibration rollers by changing length and begin of linear movement relative to the plate cylinder.

Gloss varnish Is often used to cover/protect printed images.

Grain The direction in which most fibres line, which corresponds with the direction in which the paper is made.

Grammage The weight in grams per square metre of paper, expressed as gsm.

Grey scale A strip of standard grey tones ranging from white to black, placed at the side of an original during photography to measure range and contrast.

Gripper margin The unprintable blank edge of paper in which the grippers bear.

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

Hairline register Register within ½ – row of dots.

Halftone The reproduction of a continuous tone image, which replaces contone with a stream that breaks the image into various dot sizes.

Heidelberger printing presses The most famous printing press manufacturer worldwide. Headquarter in Wiesloch, Germany.

Hickeys Spots or imperfections in printing due to dirt on the press, dried ink, paper particles, etc.

Hickey picker A soft rubber (silicone) roller which picks dirt off the printing plate.

Hollow dots Uncorrectly printed dots which lost ink in the center of the dot. Possible reason is the usage of a too hard ink.

I
Image setter A device used to output a computer image at high resolution onto film or paper.

Ink agitation Is helpful to maintain a constant distribution of pigments within the ink and is often used in the machine to mix up the ink in the cassette permanently during press operation.

Ink ductor roller Transfers the ink from the ink cassette to the roller system of the printing press.

Ink separation With waterless offset inks it may happen that the elastic share of the ink separates from the pigments and isolates the pigments under a film of silicon containing binding agent. This results in an interrupted ink transfer to the printing plate and means that the colour gets lost on the sheet/ card. High temperature and fast rotation speed support this negative effect. Reducing the ink viscosity helps in most cases.

J
Justification The spacing out of text on a page to position the text lining up left, right or centralised.

K
Kerning Adjusting the spacing between two characters.

Knockout An object positioned on a background and removing the exact area of the background it covers

Kraft A paper or board containing unbleached wood pulp – brown in colour

König&Bauer Druckmaschinen AG (Koenig&Bauer) One of the leading printing machine manufacturers in the world from Germany.

L
Laid paper Paper with a pattern of parallel lines at equal distances, giving a ribbed effect

Lamination A plastic film bonded by heat and pressure to a printed sheet, used for protection or appearance

Lpi / LPI Lines per inch; reflects the level of resolution

M
MAN Roland Printing Presses A worldwide leading german printing machine manufacturer.

Manifold A thin strong, uncoated paper used for business forms and documents, where low bulk is required

Midtone The tonal value of dots located approximately between the highlight and shadow values

Make-ready All work done prior to printing on a press – adjusting the feeder, grippers, side guide and putting ink in the fountain or duct.

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

N
Newsprint Paper made from ground wood-pulp and small amounts of chemical pulp; used for printing newspapers

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

O
Offset printing An indirect printing process which transfers the image on a flat printing plate via a blanket onto the card/sheet.

P
Perfecting press A printing press that prints both sides of the paper in one pass

Pixel A single dot on a computer display or in a digital image. A Pixel as such does not have a dimension. The actual size of the Pixel is depending on the measure DPI of the screen or any other ouput medium.

Point A traditional standard of typ measurement (12 points is equal to ± 4mm)

Pressure-sensitive paper Material with an adhesive coating protected by a backing sheet until used, which will stick without moistening.

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.

Pantone An international system of matching colour for printing, designating unique colours by standard numbers

Positive A piece of film with an image in which dark areas appear solid and light areas appear transparent.

Postscript A coding language intended for output devices

Ppi / PPI (pixels per inch) a measure of the density of scanned information in an image. The finer the optics and detector of the scanner, the higher the scan resolution.

Presstek Manufacturer of the first CTP-waterless offset printing plate which is not necessary to be developed.

Printing plate A plate consisting of an aluminum base covered by a photoreactive layer which reflects one individual colour of a multi-colour image after film exposing. It is mounted on the plate cylinder in a printing press.

Process colours The four process colour inks used in printing – cyan, magenta, yellow and black.

Proof A visual interpretation of an image to be printed

R
Radial fill A fill that this projected from a centre point outward in all directions

Ream Five hundred sheets of paper

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

Rgb image / RGB image An image containing red, green and blue as per a tv screen or in simple graphics file formats such as .BMP

Registration The exact alignment of the individual colours in order to achieve a sharp image.

Registration marks Marks that appear on film, used to check that all the colours line up

S
Screen ruling The number of dots per inch or cm. Also known as screen frequency

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

Sheet work To print one side of a sheet of paper, and then turn the sheet over and print the other side

Shadow The darkest part of an image, represented by the area with the largest dots

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 in a wide range by digital image processing.

Soft dot A type of dot whose density is not high enough, with the edges being thinner. This will create a fuzzy or flat picture in the plate-making and printing process.

Stochastic A type of positive, and a method used to achieve colours where the trouble of eliminating moiré patterns is minimised. This method still uses dots but they are generated in a random frequency and position.

Scanner An electronic device that digitises and converts photographs, slides and paper images into bitmapped images

Screen angles The angles at which halftone screens are positioned in relation to one another to avoid moiré patterns..

The set of angles most commonly used are:

Cyan = 105°
Magenta = 75°
Yellow = 90°
Black = 45°

Scumming An undesireable effect showing ink spots on originally white areas of the image. This happens if the printing plate is not able to separate the ink effectively from non-printing areas of the plate. Reasons are mostly a too high machine temperature, too high ink volume, too low ink viscosity or wrong adjustment of rollers.
In wet offset process, the reason is very often a wrong balance of dampening and inking volume.

T
Tiff / TIFF (tagged image file format) a file format used to represent black and white, grey scale or colour bitmapped images, particularly those produced by scanners.

Tint A flat even tone area of a colour.

Trap An overlap that prevents gaps from appearing along edges of an object or flat colour area in a separated image which would otherwise appear due to paper stretch or slight misalignment of a printing press.

Toray Industries, Inc., Graphic Systems Department The lone manufacturer of waterless offset printing plates worldwide, located in Japan. (except CTP-plates)

V
Varnish A thin coating applied to a printed sheet, for protection or appearance.

Vibration roller Through alternating, linear movements during rotation it makes sure to distribute the ink equally all over the total roller length. In modern offset presses there can be 5 or more of these rollers.

W
Warm colour A colour that has a yellow or red cast.

Water-Alcohol dampening Is used in wet-offset printing process to separate the ink from the non-printing sections on the printing plate.

Waterless offset Offset process without using a water dampening. The process works by using special offset plates from Toray and waterless offset inks. The process principle bases on the characteristics of a special silicone layer on the plate and the adapted silicone oil containing inks. Ink will be repulsed at places on the plate, where the silicone rubber surface is is still existing after film exposure and development of the plate.

Web The unwound material from a reel as it passes through the printing process.

Wet-on-wet Printing several colours in rapid succession, one on top of another, on a multicolour press.

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