Absorption
Soaking in or penetration of liquid components of the ink into the pores of an absorbent substrate (a type of physical drying, like evaporation).
Aniline Printing
An earlier name for flexography, based on the use of the aniline inks that were initially used.
Area Coverage Value/Area Coverage
Ratio of area coverage (area covered with image elements) to the entire area. The area coverage value is normally stated as a percentage.With reflection originals, differentiation is made into the effective area coverage value determined by optical measurements (tone value) and the geometric area coverage value determined by area measurements (with positive originals/films normally somewhat lower due to the lack of light-gathering).
Baud
Measure of the rate of data transfer. Number of bits per second (bps) that can be sent from one digital device to another.
Bit
The smallest addressable storage unit. Eight bits form 1 Byte.
Bit Depth (Depth of Data)
Defined by how many bits each pixel is described and therefore the number of gray values per pixel. Two gray values can be described by one bit (0 or 1), 256 gray values with 8 bits.
Bitmap
Image content made up of pixels where the pixels contain the information for position, size, angular position, and color and can be addressed individually.
Booklet
Book-binding product with small number of pages, often used for short-lived literature where the cover is glued or stitched directly to the spine of a block.
Brochure
Book-like finished product, normally of eight to forty-eight pages. The single or multi-layer block (folded sheets joined to one another) is inserted into a board cover (e.g., pasted in or stitched).
Browser
General: Software program that enables browsing through large amounts of data stocks. The term browser is mostly used in connection with the Internet. Here the main task of the browser is to enable access to the World Wide Web, to locate, edit, and display web sites.
CIE Color Space
Device-independent color space in which each color to be reproduced is described by its standard color values X, Y, Z (with the coordinates Y and the standard color ratios x,y).
CIELAB Color Space
Device-independent color space in which the CIE color values Y, x, y (see CIE color space) have been converted into uniform (the human color perception is recognizing color deviations within similar – but not equal – tolerance ranges) chromaticity scale values L*, a*, b*. Here, L* represents the lightness, a* is the red-green proportion, and b* the yellow-blue proportion.
CIM (Computer-Integrated Manufacturing)
Computer-integrated manufacturing of products (also of printed products)
Cliche
Common term for the plate used in pad printing.
CMYK
Standardized base colors (process colors) for four-color printing: Cyan, magenta, yellow, black. K stands for black (key color) since black is often used as a reference color for adjusting the other colors to ensure correct register/overprinting.
Color
The aspect of visual perception by which an observer recognizes optical appearance. Color is defined by three values, for instance, hue, saturation, and brightness, or L*, a* and b*.
Color Management
Process/system for calibrating the individual devices and machines that are involved in the workflow from color image processing right through to the finished printed product. Serves to guarantee correct color rendering from the input (e.g., scanner) right up to the output on various media and with various printing technologies (e.g.,monitor; through printing equipment or printing presses based on various technologies on various substrates).
Color Mixing
• Additive: light of various colors is superimposed, added by the receiving device and perceived as color. Additive primary colors are red, green, and blue (e.g., color television). If all the colors (ideal colors) are superimposed with identical intensity, the result is white.
• Subtractive: various color components within the visible spectral range are extracted from white light (e.g., through optical transmission filters). Subtractive primary colors are cyan, magenta, and yellow (e.g., for printing). If all colors (corresponding to the filtering of the white paper through transmission of the colors cyan, magenta, and yellow) are printed above one another, the result is black.
Color Separation
Splitting a color copy into the primary colors of cyan, magenta, yellow, and black (previously with the aid of color separation filters but today also possible on computers taking the digital description of the original with colorimetric data as a basis).
Commercial Printing/Commercial Printing Presses
Single- or multicolor, single- or multi-page print products such as leaflets, catalogs, notepaper, flyers, or business cards, normally in small numbers and of high quality. It is hard to define clear boundaries between illustration printing, packaging printing, form printing, an so on. As compared to special printing systems such as newspaper presses, commercial printing presses are flexible and can be used for a whole range of applications (sheet-fed or web-fed printing).
Composition
Term used for the manufacture of the text portion of a print product/the setting of type. (Completition of the page with the text, images, and graphics is called page make-up or imposition).
Computer to … Technologies
These technologies describe direct imaging from a data file either onto film (computer to film), the printing plate (computer to plate), a printing screen (computer to
screen), a closed, cylindrical image carrier such as in gravure printing (computer to cylinder), and the plate of a printing press in-line (computer to press/direct imaging) as well as via a latent image (without fixed printing master), for instance, with electrophotography, or directly onto the substrate, such as with ink jet (computer to print, sometimes also called computer to paper).
Continuous Tone (Contone)
The tone of an area not divided into image elements or non-image elements, where the small pixels/image elements are not visible to the human eye and the tone values appear continuous (e. g., analog photography, in contrast to screened halftone print images).
Copy
The reproduction of an original, whether transparency, photo, print, document, or halftone or continuous-tone film, on the same or different material.
Cross-Media
Multiple use of print data (or data describing the information content) for various media. The data can be used to create print products and web sites for the Internet, but also for the contents of CD-ROMs. The digital information generated in the “premedia” section within the production workflow can, therefore, be used to generate print media and/or electronic media.
Cylinder Rolling
The effective circumference of the plate, blanket, or impression cylinder. The rolling of the cylinders in contact with one another must be balanced and ideally identical. Rolling errors can cause dot deformation, doubling, differences in print length, register differences, and increased printing plate wear.
Densitometer
A device for measuring blackening or density values in transmission with films or reflection in the print. The measuring effect is based on a reduction in the light density as it passes through layers.
Density (Optical Density)
An ink layer’s imperviousness to light.Mathematically the logarithm of opacity in order to simulate the sensitivity of human seeing (see also opacity).
Descreening (Unsharp Scanning)
To avoid moiré effects when scanning screened originals, the originals are scanned outside the zone of sharp focus of the scanner (therefore unsharp). The image is then sharpened again in the computer. Descreening can also be done on the computer using special image processing programs.
Developing
The chemical/physical treatment of a photosensitive layer to make visible the latent image that was created during the exposure (e.g., in film imagesetting, plate imagesetting or within the electrophotographic process in the NIP technique of electrophotography).
DI (Direct Imaging)
Process of directly imaging printing plates/cylinders in the printing press (computer to press).
Di-litho
Direct printing process developed especially for newspaper printing using offset printing technology, where the paper is printed directly from the printing plate (without an intermediate blanket cylinder).
Dispersion
1. In chemistry: mixture of two or more substances where one substance serves as a dispersant in which another substance is finely distributed (dispersed)
2. In optics: defraction (wave length depending) of white light into its spectral colors when passing through the boundary between two optical media with a special
alignment and beam direction (e.g., prism).
Dithering
• In the digitally created print image the color tones are generated from the gray values for each color separation, whereby the gray values of the neighboring pixels are chosen so that the average gray value obtained in this way is as true to the respective image spot of the original as possible and hence the desired color effect is brought about.
• Resolution of gray values in a pattern of black and white microdots (e.g., in FM screening) in order to simulate a smooth/continuous transition between gray levels. Dot Gain Difference between the tone value (in percent) of the print and the corresponding tone value (in percent) of the film that is the basis for the image carrier (plate, etc.).With filmless production (computer to plate) or production without a master (NIP printing processes), the dot gain relates to the tone values of the base data for the color separation.
Doubling
A printing defect in offset printing products (and other indirect printing processes) that manifests itself as a doubled or multiple (shadow-like) contour of the image elements. Mechanical vibration and register deviations during the printing process can cause doubling. Doubling can occur in single-color printing but is a special danger in multicolor printing. As is the case with slurring, doubling results in dot gain.
DTP (Desktop Publishing)
The technology of electronic publishing (can be done in an office-like environment). Entire print pages are created on a PC with the aid of word and image processing programs and are then output on a printer or imagesetter or transmitted directly to the printing press. To be equated with digital reproduction technology today.
Duotone
Printing of images where two colors (e.g., with the inks black and gray) are printed from one original where differing screen angles, tone values, and tonal gradations are selected. Due to the better tonal gradation, a duotone print creates a better three-dimensional effect than a single-color print and is near to photographic quality.
Duplex Printing
Term for printing on both sides (face and back/front and reverse side printing) mostly used in connection with NIP processes (see also perfector).
Electronic Publishing (EP)
The creation of printed products on the basis of a digital description of the contents using digital printers/printing presses (see DTP).
Emulsion
Mixture of ink and dampening solution where the dampening solution is normally dispersed in small, equally distributed droplets in the ink (emulsified).
EPS (Encapsulated PostScript)
File format. An EPS file consists of a main file with a preview image in low resolution plus individual files containing the fine data (high resolution).
Ethernet
The most common type of network that is principally used to network all kinds of computers within a building as a socalled LAN (local area network). Thin coaxial or twisted pair cables are used for data transmission. The maximum cable length is 185 m (around 610 ft) with coaxial cables or 100 m (around 330 ft) with twisted pair cables. The data transmission rate is 10 Mbits/second. Fastethernet has transmission rates of 100 Mbits/second with twisted pair cables and 1 Gbit/second with fiber-optic cables.
Facsimile
Perfect copy/reproduction of the original (ink, screening, paper, etc.)
Fan-Out Effect
Widening of the paper web in a web-fed press, normally caused by dampening but also by printing pressure. It can theoretically occur in sheet-fed printing, too.
Film
• Negative film: the image areas without coloring are blackened
• Positive film: the areas carrying color image information (i. e., which are not white) are blackened. This means the film resembles a black-and-white image of the original.
Film Copy
Transparency (with positive or negative image) for platemaking. Each original contains all the information of a sheet to be printed for one color.
Fine Data
High-definition data that is needed for printing to ensure optimal print quality, particularly important with image data (see low-resolution data).
Full-Sheet Output
Output of the data file for the description of a complete printed sheet (one or more imposed printed pages) that can be used either for film exposure or directly for platemaking (computer to plate) without the need for further editing or producing of a complete film. See also imposition.
Fuser/Fixing Device
Subassembly in non-impact printing systems that serves to fuse powder toner and fix it on the paper. Fusers (fixing devices) normally consist of heated rollers that have an inkrepelling covering and are in contact with the substrate. Non-contact fusers with IR radiation are also common.
Ghosting
A repetitive, unwanted shadow-like manifestation in the direction of print of a previous image element. The ghost image manifests itself by over- or under-inking in comparison to its immediate surrounding area. Ghosting is influenced by the ink distribution in the inking unit, particularly on the ink form rollers. If, due to ink resplitting of the image on the printing plate, the ink profile is not reduced sufficiently (i. e., evened out) prior to the next inking process (next revolution of the roller), a partial transfer of the already printed image section into another image area will occur on the printed sheet.
Gloss
Perception based on the physical, optical property of a surface to reflect projected light more or less specularly.
Gradation (Gamma Value, Contrast)
Measurement of the ability of a light-sensitive layer of a film to reproduce density gradations. The division into gradations is made from soft to ultra-steep. An ultra-steep film material can only reproduce a very high density or the clear film. A soft film material, on the other hand, can reproduce many intermediate stages.
Gravure
Process for the manufacture of gravure printing masters/cylinders where e.g., an electromechanically controlled stylus cuts recesses (cells) into the copper layer of the gravure cylinder. The size and depth of the cells are varied in accordance with the image. The engraved cells are filled with ink in the printing process and the ink is then transferred to the substrate.
Gravure Impression Roller (Presseur)
Gravure impression cylinder used for gravure printing, consisting of a steel core covered with an elastomer coating. It presses the substrate against the plate. An electrostatic charge on the impression roller fosters the transfer of the ink out of the cells on the gravure cylinder and onto the substrate.
Guilloches
Complex geometrical, interwoven, fine, continuous line patterns on security papers and documents that make them more difficult to counterfeit.
Halftone Dot
Picture element of a screen, for instance, circular, elliptical, diamond or square-shaped. Below the middletone, the halftone dots are isolated in the image areas. Above approximately 50% area coverage the dots connect with each other.
HighlightsThe bright tones of a positive image and the corresponding areas of the negative (film).
Hybrid Technology/Process
The linking of various, normally separate technologies within one functioning unit, for example, the combination of analog and digital technology or, in the case of print media production, the combination of various print technologies in a single production system (e.g., offset and flexographic printing or offset and NIP technology).
Hydrophilic
Water-receptive. In offset printing the non-image areas on the printing plate that are repellent to ink (oleophobic).
Hydrophobic
Water-repellent. In offset printing the image areas on the printing plate that are receptive to ink (oleophilic).
Illuminant
Expression used for light with a precisely defined relative spectral distribution, such as color temperature T=5000 K as the D50 illuminant, or T=6500 K as D65 (average daylight). Ascertaining the illuminant is important for the matching of color prints.
Illustration Printing
Printing of magazines that appear regularly (as periodicals).
Image Carrier
Appliance whose surface is prepared in such a way that the selected areas transfer ink to the substrate (directly or indirectly via an intermediate carrier).
Imposition
Arranging the individual pages on a print sheet, taking the folding layout and finishing into account. (The arrangement of text, graphics and images within one page is called page layout/make-up.)
In-Line
Carrying out processing steps with a hardware and software connection (linking) of the units to the printing press. Devices for coating, folding or stitching can be linked to the press. (In-line quality control means that the measuring device is integrated in the press and the quality is measured and checked within the production stage).
Ink
Substance (liquid, pasty, solid or pulverized) which generates visually perceivable information on the substrate. (Specific for each printing process.)
Ink Fading
Term used in offset printing for the variation in the ink density (uneven ink film) in the direction of print (as a consequence of inking unit design and content of the printing sheet).
Interface
Connection between subassemblies, for example, individual electronic components or programs.
Job Ticket
Term used for a digital ”job docket” containing information on the operations in prepress, printing and in finishing. It specifies the print job and the means of production and contains technical, organizational, scheduling, and administrative information.
JPEG (Joint Photographic Experts Group)
Data format and compression algorithm for color images. Often used in digital cameras (photography). Offers advantages for Internet applications due to the relatively small amounts of data involved.
Justifying
Altering the space between individual letters or words in order to make the line fit a length specified in the layout.
Latent Image
An image that is present but not visible (hidden) on the exposed, still undeveloped film of a printing plate or on the photoconductor in electrophotography.
Letterset
A printing process using a metal relief plate from which the image is transferred to the substrate via a blanket cylinder.
Long Grain
Term used for a print sheet that has been cut from the paper web in such a way that the grain of the paper runs along the long side of the sheet (direction in which the paper web runs during production. See also short grain).
Low-Resolution Data (Low-Res)
Data for displaying low-resolution images and text, used solely for design and layout purposes. The advantage of this rough data is that relatively small amounts of data, which can be processed quickly, are involved. This is especially useful with image data (e.g., original data/fine data (highres) for an A4 color image is around 40 Mbytes and with low-res data around 2.5 Mbytes).
Matrix (die)
A type of mold used in letterpress and flexographic platemaking. Depending on the type of cast (stereo), various materials are used for the matrix, such as cardboard, plastic, lead, wax, and so on.
Misting (Flying)
Side effect of ink film splitting within an inking unit, in particular on rapidly-rotating inking rollers. Here, extremely small droplets (diameter of 10 to 50 μm) of ink are released from the ink layers on the exiting nip. They form an aerosol with the ambient air, can lead to printing defects, and contribute to soiling of the press.Misting is very much dependent on the rheology, in particular the tackiness, of the ink, as well as on the velocity of the ink-carrying surface and the geometry of the rollers. (See also spraying for comparison.)
Modem
Interface (normally serial) between a telephone network and computer. A modem is both transmitter (output of computer data to the net) and receiver (of data sent). The term modem originates from broadcast engineering and is created from the terms MOdulator and DEModulator.
Moiré
Undesired pattern (interference) in halftone (normally multicolor) images, which is normally caused by incorrect screen angles, register errors, or special patterns in the original in connection with the screen angle.
Mottling
1. Scanning: surface effect in the entire image. Often caused by focusing too strongly. This means that the individual pixels or even the grain of the film become visible.
2. Printing: spotty, mottled appearance of prints due to differing ink absorption into the paper. Particularly noticeable in multicolor prints.
Multiple-Ups
In printing technology the number of identical copies on the same sheet. In reproduction technology (step-and-repeat copying) the aligning of identical motifs at certain distances apart in one or two directions by photograph shots or copying.
NIP (Non-Impact Printing)
Printing processes that require no permanent printing master and are therefore able to generate a different image with every print. The most important NIP processes are electrophotography and ink jet.
OCR (Optical Character Recognition)
Computer-aided system for optical character recognition. The text recognized can then be used in a text processing program (similar: MCR/magnetic character recognition, where automatic reading takes place via magnetic sensors when printing with magnetic ink).
Off-Line
Individual modules (devices/machines) of a system are not directly linked to one another (are not mechanically and/or electrically linked), but a data link is quite possible. For the creation of printed products, i. e. individual finishing operations like folding or trimming printed sheets are performed separately from the printing process outside the press and independent of its momentary application.
Oleophilic
Surface property based on interfacial effects; oil-receptive, ink-accepting/receptive.
Oleophobic
Surface property based on interfacial effects; oil-repellent, ink-repellent.
On-Press Proof
Sample print on a printing system in a small run length that shows the result of the reproduction process, whereby the technology of the proofing system corresponds to the printing process used for the print run/job.
Opacity/Opaque
• In general: the ability of a material to absorb light. The measurement for opacity is the reciprocal of the degree of transmission (transparency)
• Measurement of imperviousness to light by paper and other materials. Significant when printing on both sides of paper. A high opacity of paper is achieved both by the addition of fillers such as kaolin, talcum, or titanium dioxide as well as by using a greater proportion of wood. This means that the print image of the front side does not show through to the reverse side.
• Offset inks are generally not opaque. They are translucent.
OPI (Open Press Interface)
A server-aided interface that enables a low-resolution version of the image to be produced when displaying PostScript files for layout purposes. These previews are used for further processing of the layouts and image assembly. The previews are then automatically replaced during imaging (film, plate) by high-resolution images.
PDF (Portable Document Format)
Part of the Adobe Acrobat data format that enables a platform and program-independent exchange of documents.
Perfecting (Face and Back Printing)
Printing both the front side (face) and reverse side (back) of a sheet in single pass on a printing press (see also Duplex printing).
Perfector
Printing press with a sheet turning device enabling both the front and reverse side of the substrate to be printed in one pass (in particular machines based on the NIP technology are referred to as duplex printers).
Personalizing (Individualizing)
A printed product whose content has been totally or partially generated for one specific customer. In its simplest form this can be just the address (text portion personalized), but it extends to brochures that are compiled to
represent the special interests of the recipient, such as
guidebooks with routes, accommodation, and time scales specific to an individual. Parts of the content remain constant and identical to other editions and other parts are adapted, altered, or added to meet specific requirements.
Photopolymer
Plastic that is cross-linked (hardens) under the influence of light.
Piling
Undesired build-up of printing ink on ink transfer surfaces of the printing unit, for instance, on the blanket in multicolor wet-on-wet printing.
Pixel
Created by breaking down an image into discreet picture elements. The pixel is the smallest picture element that can be processed (addressed) by an electronic system (e.g., monitor, printer, imagesetter, scanner, digital camera). The term is derived from picture element.
Pixel Format
Format for saving image data where each pixel is described by corresponding data. The most common pixel format is TIFF (Tagged Image File Format). The pixel format is suitable for images, although a large amount of memory may be required, particularly with high image quality (high resolution).
PostScript
Device-neutral page description and programming language developed by Adobe Systems for texts, graphics, and continuous tone images. Also format for text and image information.
Preflight Check
Inspection of a file for the description and definition of a print job, for instance, for the production of films or plates, to ensure that all the image and text information (e.g., status, correct fonts, imposition, acceptance when transmitted to various production units, etc.) is present and complete.
Primer
Colorless varnish with low viscosity used as a base coat on the substrate (to improve wetting and bonding). Primer is applied prior to the actual varnish to enhance the gloss, particularly in connection with UV varnishes or prior to the application of glue for improved adhesion.
Print Characteristic Curve
The diagrammatic representation of the relationship between the tone values of the prepress products, for instance, halftone data (tone values) of the film or the printing plate (normally this applies to the tone values of films), and the corresponding tone values in the print. (The phenomenon – increasing tone value in the print compared with the tone value in the film – called dot gain is derived from this.)
Print on Demand (PoD)
A print product is not printed for the total run length in one run and then stored, but is printed as required or at least in part runs. The extreme scenario is when single copies are printed upon the customer’s request.
Printing Pressure (Contact Pressure)
Physical pressure that is generated in the nip to enable the ink transfer from the printing plate to the substrate or from the printing plate to the blanket and then from the blanket to the substrate.
Process Colors (for four-color printing)
Yellow, cyan, magenta, and black (see C, M, Y, K).
Proof (Proofing)
Process used for quality control in prepress and printing regarding color reproduction, register, text and image layout, or as a specimen for the production run. Proofs are differentiated into analog and digital according to the type of original. Analog proofs are produced photomechanically from films that have been exposed, for instance, using color foils. Digital proofs are produced using a NIP technologybased color printer (normally based on ink jet or thermal sublimation processes) from the digital data file. The expected print result on a production press should be reproduced as accurately as possible. This is supported/ achieved by using color management systems (see on-press proof).
Register
1. Positional accuracy of the print images on the front and reverse side of a print sheet in relation to one another. In perfecting the term perfecting register is also used.
2. In multicolor printing the position of the color separations relative to one another (color register).
3. Term used for the positional accuracy of the color separations on the printed product with reference to the outer edges of the sheet or web section. Circumferential register is used for the direction in which the substrate runs, for example the plate cylinder revolves; lateral register is at right angles to it.
Rendering
• Another expression for screening (see screen)
• The term continues to be widely used for the conversion of three-dimensional scenes into two-dimensional images. Here, rendering refers to the process of illustrating a three-dimensional scene (with bodies and their illumination) in a two-dimensional view (e.g.,monitor display) with light and shadows. Rendering is also required with animated images and virtual reality representations where each individual image is rendered.
Reproduction Technology
• Analog: technology using predominantly photomechanical, chemical, and physical means for image processing.
• Digital: technology where electronic means such as scanners, computers (including software), imaging devices, and so forth, are used for image capturing and image processing.
Resolution/Addressability
Number of image elements (dots, pixels) per unit length that can be reproduced on a monitor, film, an image carrier (printing plate, etc.) or on paper. Normally expressed in units (dots) per cm (dpcm) or inch (dpi). High resolution means good rendering of detail.
Resolution Capability
Defined in photography by the number of separate lines per millimeter that can be reproduced with a tone value of 50% (dark and light lines with the same width).
Rheology
Study of the flow and deformation behavior of liquid as well as solid or gaseous substances. One rheological parameter for the description of fluids is viscosity.
RIP (Raster Image Processor)
The information of a page (digital structure in image, text, and graphic elements, and positional commands) arriving in the RIP is converted into a bitmap file. The significant processes here are the screening and generation of data for addressing the output device.
Run Length
Number of copies to be printed in a print job.
Scanning
An original is analyzed and captured line by line to convert the analog image information from an original into digital data. This can be further processed in the computer. The term scanning is also used for the transfer of information (e.g., by light or by ink) to a carrier substrate via a moving imaging system.
Screen
Area broken down into printing and non-printing picture elements (halftone dots or lines) where the size and/or number of dots per area varies according to the tone values of the original. The two main kinds of screening are amplitude-modulated and frequency-modulated screening. Screening a continuous-tone original to generate a halftone image is today predominantly an electronic process.
Screen Frequency (Screen Definition, Screen Ruling)
Number of print picture elements such as halftone dots and screen lines per unit length in the direction that yields the greatest value.Measured in cm-1 or lines per inch (lpi). Therefore, in a 60 lines/cm (150 lpi) screen (typical value in offset printing), 60 halftone/screen cells formed by screen lines lie within a length of 1cm.
Scumming
In offset and NIP printing processes, the inking/printing of areas outside the print image that do not correspond to the print image. This can be caused by surfaces of the image carrier accepting ink in the wrong areas or by the blanket (indirect printing) having a defective surface and transferring ink to the wrong areas.
Server
Computers that offer certain services in a network as a component of a client/server system. In the area of prepress powerful computers are employed as data servers to store comprehensive amounts of text and high resolution image data centrally.
Sharpness
Reproduction quality of contrast gradients, particularly lines and contours of a picture or line art original. Normally given as definition or detail rendering (reproduction). The output resolution of reproduction or printing devices serves as a reference.
Shore Hardness
Measurement of the hardness of materials such as elastomers (roller sleeves made of rubber, flexographic printing plates, etc.) defined in accordance with ISO 868. The greater the value of shore hardness (in degrees), the greater the hardness of the material. Depending on the hardness of the material, various conditions are applied for testing. Shore A, for example, is used for soft rubber and Shore D for hard plastic.
Short Grain
Term used for a print sheet that has been cut from the paper web in such a way that the grain of the paper runs along the short side of the sheet (travel direction of the web during papermaking). This holds true for other materials, such as plate material for printing plates (see also the opposite, i. e., long grain).
Signature
1. Used to mark the first and last page of the folded sheet (e.g., 17 and 32 for the second folded sheet in 16-page format) to support the correct location and sequence during finishing to produce book blocks (several folded sheets collated and bound). The signature is normally removed when trimming the block.
2. Term commonly used for a print sheet which when folded and cut forms a group of pages. In web printing term meaning a web section printed in accordance with the print format.
Sleeve
Printing master or blanket sleeve. Sleeves allow the cylinders to roll smoothly against one another since they eliminate the cylinder gaps which are normally present on the circumference of the cylinder. Sleeves enable continuous printing and reduce trim waste since image-free areas can be avoided.
Slurring
Slurring is a printing defect that occurs in offset printing. It manifests itself as changes in the geometry of the halftone dots. Round elements may be deformed and become oval. Slurring in the direction of print is classed as circumferential slurring and slurring at right angles to this as lateral slurring. This effect is related to the rolling behavior between plate, blanket, and impression cylinders and to influences of the materials.
Spectrophotometer
Term for a measurement device used to determine color values, such as chromatic value, (h*: hue) brightness (L*), and saturation (C*:chroma), with which color can be clearly classified quantitatively in accordance with the color perception of the human eye (in contrast to densitometers, which can only determine ink film thickness via the optical density).
Spot Color
Special colors. Used in addition to or instead of process colors (C, M, Y, K) to enable the printing of special hues without mixing the primary colors. Often also the only chromatic ink used in black-and-white printing.
Spraying
When large ink particles (diameter roughly greater than 80 μm) are thrown off the rollers in the inking unit or the printing plate, particularly with presses that run at high speeds (see also misting for comparison).
Spreads and Chokes (trapping/choking)
In reproduction technology the term spreading is used to describe the overlapping of two bordering inked areas. The areas are placed close to one another so that register errors do not become visible in the form of undesired white areas. This is also called trapping. Choking can then become necessary if negative structures (e.g., text) are printed in a multicolor area.
Substrate
The material on which the image is printed.
Suspension
Liquid in which the extremely fine solid particles are “suspended” (solid component in a liquid carrier component, not solved).
Tabloid Format
Half-size format in newspaper printing (half the web width) compared to the broadsheet format (full web width). The paper web is split on the former and the partial webs are laid above one another, after that a parallel fold (also called tabloid fold) is performed. One way of recognizing a tabloid-format newspaper is that the punctures of the needles are at the sides (with the broadsheet format the punctures are at the bottom). Newspapers in the broadsheet format are folded lengthwise in the former and crosswise in the folding cylinder.
Tack
A property of printing inks that describes the cohesion that exists between particles of the ink film, the force required to split an ink film or, in other words, its stickiness.
TIFF (Tagged/or Tag Image File Format)
The most common pixel format; it is supported by virtually all systems. Among other things, this format is suitable for the data exchange of color images and gray values as well as various levels of resolution and sizes.
Tone Value
Unit of measure of the optical impression of a screened area, stated as a percentage, where the unprinted surface represents a tone value of 0% and the solid tone surface a value of 100%.When screening, the tone value represents the ratio (in percent) of the halftone dots to the entire area.
Transmission Copy
Original copy (film) for platemaking on a transparent substrate whose image information is either transferred to the printing plate in direct contact or through optical projection.
Transparency
The property of a material to allow radiation (e.g., light) to pass through.
Transparent Ink
Translucent ink layer, the opposite of opaque ink. Printing inks are predominantly transparent inks. The translucent, color filter effect is a prerequisite for subtractive color mixing.
Trapping
1. Ink-trapping characteristics with multicolor overprinting.
2. Spreads or chokes in reproduction technology when generating the image (see spreads).
Types of Sheet
• Print sheet: printed sheet, as it comes out of the printing press.
• Bookbinding sheet: sheet trimmed after the printing process, input sheet for the folder.
• Folded sheet: folded bookbinding sheet, product of the folder.
Vector Format
Digital data format with which line images (line art, text) are not saved in the form of individual picture elements (pixels), but rather in the form of line elements, defined by the starting and end point (“vectors”) and line width. Advantages compared to the pixel format are usually scalability without any loss of image definition and the fact that significantly less memory is required.
Version (customizing/targeting)
The entire print run of a printed product is divided into partial runs (versions), for example, by changing the content or language of text portions of otherwise identical content, such as addresses of an organization or a company group with various regional sites or various language versions (such as the same text in partial run 1 and English text in partial run 2). It is then not individual persons that are addressed directly (as in personalizing), but rather groups of customers or target groups.
Viscosity
The viscosity describes the property of a substance to flow and be deformed irreversibly under the influence of mechanical stress. The dynamic viscosity (h) is generally given to classify the rheological property of fluids, such as ink.
• Dynamic viscosity (h), measured in Pa·s, is the quotient of the pressure in the layer surface and the velocity gradient.
• Kinematic viscosity (n), measured in m2/s, is the quotient of the dynamic viscosity and density of the substance.
VOC (Volatile Organic Compounds)
International term for volatile organic (containing carbon) compounds with the exceptions of methane, carbon monoxide, and carbon dioxide. In offset printing, IPA dampening solution alcohol and solvents used for cleaning are by far the most important VOCs used in terms of quantity. In gravure printing,methylbenzene (toluene) is the
most common one.
Wet-on-Wet Printing
Printing in multicolor presses. The printing of the second or another ink takes place on the previous ink, which has not yet dried.
Workflow
Description, organization, and monitoring of operations; process steps for the production of goods. The working areas/ process stages (sections) of premedia, prepress, press, postpress, roughly speaking describe the stages of production from the idea right through to the finished print product. The workflow can be networked to varying extents. With a digital workflow, documents are transmitted from one stage of operations to the next with the aid of a computer system/network.