D
DAMPING
The procedure of applying water to the lithographic plate on a litho printing machine. Also the application of moisture to
paper in preparation for a subsequent process, e.g., supercalendering.
DAMPING ROLLER
The roller on a printing machine that enforce the moisture directly to the printing plate.
DANDY ROLL
A light skeleton roll or cylinder, covered with wire gauze, which exerts light pressure on the wet web of paper at a point near the first suction box. Its purpose is to mark the sheet (web) with a design carried on the surface of the roll, either to produce a wove or laid effect in the web, or, when letters, figures, or other devices are worked in wires on the surface of the roll, a watermark. In the latter case, the roll is known as a watermarking dandy. Originally, the dandy roll was driven by the Fourdrinier wire, but with the development of higher speed papermaking machines, it became the practice to drive the dandy roll separately in order to eliminate drag which would result in distortion of the watermark. Plain dandy rolls are now used extensively to level the surface of the web and improve or assist in sheet formation.
DECKLE
See Machine Deckle.
DECKLE FILL
See Machine Fill.
DE-INKING
The removal of printing ink and mechanical impurities by flooding and/or washing pulped wastepaper before it is recycled.
DIMENSIONAL STABILITY
Ability of a paper to retain its dimensions and its shape (1) despite changes in its moisture content under the influence of, for example, variations of the surrounding atmosphere or varying degrees of temperature, or (2) despite variations of the physical and mechanical stresses during printing and converting operations or use.
DISSOLVING PULP
Highly purified chemical pulp intended mainly for conversion into chemical derivatives of cellulose.
DOCTOR
A blade-like device that rests on the up-running surface of a roll in order to keep it clean by removing any foreign matter sticking to the roll.
DOUBLING
The appearance on the printed sheet, locally, of two non-coincidental images obtained at one stamp.
DRIERS
Substances, generally metallic compounds, added to an ink to increase the rate of drying by accelerate action.
DRY END
The papermaking machine part where the paper passes through steam-heated drying cylinders.
DRY OFFSET
A procedure of printing, as in the offset lithographic method, but from a relief plate and without the use of fountain solution.
DUCT
The moat on a printing machine, usually including an adjustable blade, which contains the supply of ink and by means of which the ink is presented to the duct roller.
DUCT ROLLER
The cylinder in the duct of a printing machine that, in conjunction with the adjustable knife blade, manages the amount of ink applied to the feed roller.
DUMMY
An unprinted representation of the text pages of a book made by fittingly folding and collating sheets of the intended quality and grammage of paper so that an idea may be formed of the general appearance and thickness of the ultimate book.
DUPLEX CUTTING
The operation of converting a web of paper into sheets on a cutting machine provided with two cross-cut knives so that two different lengths of sheet can be cut simultaneously.
