Mar 11 2010

Glossary of Terms for
Paper and Printing

"D"

DAMPENING SYSTEM

The dampening system of offset presses has the task of drawing a thin film of dampening solution - water with a component of isopropyl alcohol and other additives - over the non-printing areas of the form. We can distinguish between, on the one hand, vibrator-type dampening systems and dampening systems where direct contact exists between the dampening solution holder and a vibrator cylinder and, on the other hand, centrifugal, turbo or brush-type dampening systems which do not have this direct contact. With indirect systems, the dampening system feeds the dampening solution to an inking form roller which in turn feeds ink and dampening solution in dispersion form to the printing plate.

DANDY ROLL

A wire mesh cylinder on papermaking machines that makes watermarks or a laid or wove finish.

DATA COMPRESSION

In computer engineering, 'compression' is the term used for the reduction of the memory space required for data by optimizing the binary notation of the information. Depending on the nature of the original data and their coding, compression ratios of 1 : 100 and more can be achieved in this way, thus saving memory space and/or transfer time. A distinction is made between compression methods that involve a (more or less acceptable) loss of information and 'non-lossy' methods. Typical 'lossy' methods are JPEG for images and MP3 for music. Methods for compressing numerical data, such as MNP5 and V.42bis for data transmission, and also compression methods for files (zip, lha, rar, etc.), are of the non-lossy type for obvious reasons

DATABASE

A Database is an electronic filing system; An organized collection of information, characterized by the use of data fields, it provides a foundation for procedures such as retrieving information, drawing conclusions, and making decisions. Traditional, computerized databases are organized by fields, records, and files. A field is a single piece of information; a record is a complete set of fields; and a file is a collection of records.

DE-INKING

Process consisting of separating the ink from the fibres. This process is only carried out when the end-product needs it, such as for printing and writing paper, for magazines, for cellulose wool, and for certain types of packaging.

De-inking consists of separating the ink particles mechanically and through the use of soap to create bubbles. While fixing themselves on particles of ink, these bubbles float up to the surface of the vat and are then recovered.

According to their composition, the sludge derived from de-inking can be reused in the agriculture and forest management, as soil amendment or to find other applications.

DEBOSSING

The opposite of embossing. Instead of a raised image, letters or images are depressed into a sheet with a die.

DECKLE

The untrimmed edge of the web of paper as it comes off the machine. (Also used to denote the width of the web).

DECKLE EDGE

Feather-edged sheets that trace their origin back to early handmade papermaking when the pulp slurry seeped under the molding frame (deckle) causing the edges to feather. The feathered edge of a sheet produced by blowing streams of air or water at the edges of the web (roll) as it is being manufactured.

DEFAULT

A computer software setting or preference that states what will automatically happen in the event that the user has not stated another preference. For example, your computer may have a default setting to launch or start Netscape whenever a GIF is opened; if you prefer to use Photoshop whenever you need to view a GIF, you can change the default setting.

DELAMINATION

The internal splitting of paper in the printing nip which occurs most on the heat-set web offset blanket-to-blanket presses. It is due to a weakness in the body paper or high ink tack. Separation of the ply bond of boards or laminated paper materials.

DENSITOMETER

A printer's tool used to make sure that the ink colour stays accurate and consistent throughout a print run.

DENSITY

The weight of a sheet of paper relative to its bulk. Compacting fibres create a dense paper.

DIALOG MARKETING

The term dialog marketing includes all company activities aimed at addressing potential customers directly in order to obtain a direct response. One typical tool of dialog marketing is mailshots (personalized communications) containing various response options. Many advertising professionals regard the Internet as the customer dialog medium of the future.

DIAMETER

The outside diameter of the roll.

DIE

Metal object crafted from artwork and used to create embossings, cut shapes or apply foil.

DIE-CUTTING

Using a metal-edged die or laser, shapes are cut into paper. This may be for the purpose of creating a decorative pattern or for functional needs such as making a pocket folder or printing shapes labels etc.

DIGITAL CAMERA

Instead of conventional light-sensitive film, digital cameras use highly-integrated components (CCD chips), which convert the image captured by the lens into digital data. This circumvents the use of film imaging, film development and scanning. In print and non-print media production, this saves time while also offering greater flexibility. There are digital cameras available for a whole range of applications, from recreational use to use in a professional capacity. As a rule studio cameras use separate digital units instead of traditional film cassettes.

DIGITAL HOLOGRAPHY

Digital or synthetic holography is the term used for generating holograms, i.e. illustrations in the form of interference patterns, through computer calculations instead of light interference. Future applications for digital holography include high-capacity, long-term data storage devices based on plastic foil and ultra-small, forgery-proof markings for packaging, etc.

DIGITAL PHOTOGRAPHY

As an alternative to conventional processes which use film imaging and film development, digital photography uses cameras which capture images directly in digital form. The image data is transferred by means of special storage media or a data interface to a computer for further processing.

DIGITAL PRINTING

In a general sense, digital printing refers to printing processes in which the information is transferred from the computer directly onto the paper, without need for film and printing plates. It links colour printing technology with the printing press' mechanical system. Digital printing cannot achieve the same level of quality as conventional printing processes, but it is faster and more cost-effective for small print runs and allows special techniques such as personalized printing or printing-on-demand.

DIGITAL SIGNATURES

A digital signature is a type of 'seal', which is created using a chip card and is based on encryption software (mathematical processes). Digital signatures are used in electronic communication to provide a legal alternative to the handwritten signature. These are ideal, for example, for electronic tax returns, home banking and electronic transactions (e-commerce).

DIMENSIONAL STABILITY

A paper's ability to keep its size and shape, particularly when exposed to humidity changes and the rigors of the printing process. Dimensional stability is essential for keeping forms in registration during printing and keeping sheets from jamming or wrinkling on press or in laser printers.

DIN SIZES

These standard metric sheet sizes are widely used outside the United States. The most important ones belong to the A series, in which the next-smaller size has a length corresponding to half that of the next-larger size. They include A4 (210 x 297 mm) and A3 (297 x 410 mm).SEE OUR SEPARATE PAGE IN KNOWLEDGE BASE FOR STANDARD PAPER SIZES

DIRECT IMAGING

Direct imaging refers to a new technology which uses PostScript data from the prepress stage to simultaneously image all the printing forms of a printing press with complete register accuracy. To do this, the screen data supplied by a RIP (raster image processor) controls 64 infrared laser diodes, creating small recesses on a special printing foil with an ink-repellent surface, thus revealing an inking layer. The result is a printing foil which can be used for water-free offset printing.

DISPERSION

Following the deinking process of waste papers, residual ink particles are dispersed into tiny bits that are usually invisible to the eye. Bleaching the fibres helps to remove the last of the inks and improve paper brightness.

DISTRIBUTER

A user type that acts in both the buyer and seller roles.

DITHERING

Alternating the values of adjacent dots or pixels to create the effect of intermediate values or colour.

DOCTOR

Thin blade of wood, metal or plastic, placed against rolls on the machine to keep them clean and smooth.

DOD

Drop on Demand. An inkjet technology describing ink ejected from an orifice drop by drop as it is required to form the image. There are two technologies Thermal Bubble Jet and Piezo-electric (q.v.).

DOT COMPENSATION

Coated and uncoated papers tend to absorb ink in different degrees. To adjust for these varying absorption levels, printers alter the size of the dots in halftones and four-colour images to compensate for dot gain.

DOT GAIN

The tendency for the dots of halftones and four-colour images to print larger than they are on the film or plate. Printers adjust for dot compensation based on the type of paper selected to make sure images don't look distorted.

DOTS PER INCH (DPI)

In lithography, the number of dots that fit horizontally and vertically into a one-inch measure. Generally, the higher the dpi, the sharper the printed image. DPI is a strong, but not the only determinant of image quality.

DRIVERS

Software that instructs the computer on how to talk with its specific peripheral components, such as scanners, drivers and printers.

DRY END

The drying and calendering section of the papermaking machine, which follows the press section, where most of the water is removed from the sheet, and surface smoothing is done.

DRY TRAP

The process of applying a second layer of wet ink over a layer of dry ink that had been run previously in a separate pass through the press. Although more expensive, dry trapping provides a sharper image than wet trapping because the ink isn't diluted by the other layer of wet ink.

DRY-END

That part of the paper machine where the paper is dried, calendered, and reeled.

DRYING

The process of winding the web of newly formed paper through a series of heated metal drums to bring the moisture content of the sheet down to approximately 5%.

DRYOGRAPHY

Waterless offset lithography which facilitates the use of very fine line screens for high-resolution printing.

DUMMY

An exact, handmade format sample created with blank paper to show the desired size, shape, weight and general appearance of a project prior to production.

DUOTINT

A one-colour halftone printed over a screen of a second colour halftone.

DUOTONE

A two-colour halftone of the same image created with two screens, two plates and two colours. Generally the full tonal range is printed in black and the middle range of tones are printed in the second colour to create an effect that is deeper and richer than a one-colour halftone.

DUPLEX BOARD

A multi ply construction of a board made predominately from mechanical pulp but with a bleached chemical pulp liner.

DUPLEX PAPERS

Feature a different colour on each side of the sheet, laminated together.

DUST

Loose flecks of fibre, filler and/or coating on the paper that sometimes sticks to the printing blanket and prevents ink from reaching the paper surface.

DYE BASED INKS

A very common ink type in which the colourant exists as individual dissolved molecules rather than solid particles. Dyes may be dissolved in water or solvents, and can form bright colour. However, they are very much coating dependent, usually with low UV stability and slower dry times on coated substrates.