DAMPING
The process 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 applies the moisture directly to the printing plate.

DANDY ROLL
The roll on the wet end of a papermaking machine that is covered with a woven wire and carries a design to form a watermark in wet pulp.

DECKLE
See Machine Deckle.

DECKLE FILL
See Machine Fill.

DE-INKING
The removal of printing ink and mechanical impurities by flotation 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 (2) despite variations of the physical and mechanical stresses during printing and converting operations or use.

DISSOLVING PULP
Highly purified chemical pulp intended primarily 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 adhering to the roll.

DOUBLING
The appearance on the printed sheet, locally, of two non-coincidental images obtained at one impression.

DRIERS
Substances, generally metallic compounds, added to an ink to increase the rate of drying by catalytic action.

DRY END
The part of a papermaking machine where the paper passes through steam-heated drying cylinders.

DRY OFFSET
A method of printing, as in the offset lithographic method, but from a relief plate and without the use of fountain solution.

DUCT
The trough 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, regulates the amount of ink applied to the feed roller.

DUMMY
An unprinted representation of the text pages of a book made by suitably 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 equipped with two cross-cut knives so that two different lengths of sheet can be cut simultaneously.