Dampeners
In lithography, cloth-covered, parchment paper or rubber rollers that distribute the dampening to the press plate.

Dampening solution
Water, gum-buffered acid and various types of etches used to keep the non-image areas of the plate moist and to prevent them from accepting ink in the lithographic printing process; also called fountain solution.

Dandy roll
(1) A plain roll situated above the wet web of the paper to provide a smoothing action to the top surface of the paper as it passes under the roll. (2) A watermarking dandy roll is a roll of skeletal structure, sheathed in a wire cloth that has designs, letters or figures affixed to it. As the wet paper web passes under the turning watermark dandy, the designs are impressed into the paper and a permanent watermark is left in the sheet.

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

Deckle
On the wet end of the paper machine, the straps or deckle rulers that prevent the fiber from overflowing the sides of the machine. The deckle determines how wide the paper on a particular machine will be.

Deckle edge
Refers to the feathered edge on paper produced when fibers flow against the deckle or edge of the web. Deliberately produced for aesthetic purposes, a deckle edge is found especially on formal stationery and announcements. A deckle edge can be created either by an air jet or by a stream of water.

Decurler
A device on a web press or sheeter used to remove paper curl.

De-inking
The process of removing toner, inks, coatings, sizing, adhesives and impurities from waste paper before recycling the fibers into a new sheet. The environmental priority is to make this process TCF, or totally chlorine free.

Delamination
Separation of a paper's surface.

Delivery
Area of the originating press where freshly printed sheets are piled as they leave the impression section.

Densitometer
Reflection instrument measuring the density of colored ink to determine its consistency throughout a press run.

Density
The weight of a sheet of paper relative to its bulk; directly related to the paper's absorbency, stiffness, and opacity. Compacting fibers create a dense paper.

Descender
The parts of lower case letters that extend below the baseline.

Diagonal seam (envelopes)
Seam style frequently used in commercial open-side envelopes as well as announcement, invitation and baronial envelopes.

Die
Precision tool used to cut shapes into paper, envelope blanks; windows or other shapes.

Die-cutting
Using a metal-edged die or laser, shapes are cut into paper for the purpose of creating a decorative pattern or for functional needs, such as making a pocket folder.

Digital color printing
A printing process that allows color printing directly from electronic images without the need for film or color separations.

Dimensional stability
A paper's ability to maintain its size and shape (i.e., resist dimensional change), particularly when exposed to relative humidity changes, change in moisture content 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.

Dirt count
The average amount of dirt in a specific size of paper area. Both virgin and recycled sheets have "dirt," although recycled paper has significantly higher dirt counts. The dirt should always be small enough not to interfere with the quality of the finished printed piece.

Dished
Concave rather than flat pile of paper. Also refers to roll ends of paper that are not flat.

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

Distributor
A company that purchases paper from a mill for resale to printers and end-users. Usually a distributor has protected or franchised product lines and territories. Inventory, warehousing, distribution and transportation of product are among the many services offered to paper buyers. Also called a merchant.

Dot
Individual element of a halftone printing plate.

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-color images to compensate for dot gain.

Dot etching
Handwork on engravings and lithographic screened (halftone) negatives for correcting tonal values in either black-and-white or color work.

Dot gain or spread
Dot gain is the tendency for the dots of halftones and four-color 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 do not look distorted.

Dot slurring
Smearing or elongation at the trailing edges of halftone dots.

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. Also, a measure of the resolution of a screen image or printed page. Spots per inch (spi) is a more appropriate term.

Double-black halftone printing
A means of extending the range of density available with printing ink by printing twice with black ink using two specially prepared halftone negatives. Also called double-black duotone.

Double-deckle paper
A paper having parallel deckle edges.

Double-dot halftone
Two halftone negatives combined onto one printing plate, having greater tonal range than a conventional halftone negatives. One negative reproduces highlight and shadows, the other - middle tones. This is not to be confused with duotone or double-black printing.

Double-thick cover stock
A cover stock composed of two sheets of 65 lb. cover stock laminated together.

Double Inside Side Seam (DISS) (envelopes)
Type of seam configuration on open-side envelopes where seams tuck beneath back panel.

Double Outside Side Seam (DOSS) (envelopes)
Seam configuration on open-side envelopes where seams are glued on top of back panel.

Double-thick or d.t. cover
Describes a sheet of paper made by bonding two thicknesses of paper together resulting in an extra-stiff sheet.

Double varnish
Two applications of press varnish.

Doubling
(1) In printing, a press problem that generally occurs when sheets make contact with the blanket twice, once just before the impression point and the second time at the impression point, resulting in a double image. At times, with certain papers, the feeder will feed two sheets instead of one, and when pressures are extreme or out of balance, the blanket may slip at the pressure point, resulting in a slur or double image. (2) In stamping, a double impression in which the second impression or "hit" does not register perfectly over the first one.

Doughnut hickey
A printing defect consisting of a solid printed area surrounded by an unprinted area.

Downtime
Duration of an unscheduled stoppage of machines or equipment (printing presses, papermaking machines, typesetting equipment, etc.), usually caused by malfunction.

Dpi (dots per inch)
See above.

Drag
Register trouble when the dot is enlarged toward the back (nongripper edge) of the sheet. Also see slur.

Drawdown
In inkmaking, a term used to describe an ink chemist's method of roughly determining coating or color shade. Also, the application (by a blade or a bar) of a thin film of coating or ink to a piece of paper.

Drilling
Piercing of stacks of paper or envelopes in a precision manner with round hollow drills at high speeds. Loose-leaf notebook paper is an example of drilled paper. Interoffice and bank teller envelopes are often drilled to ensure that all contents are removed by the recipient.

Drop-out
In printing, halftone with no screen dots in the highlights or background. Also, color not sensed by optical reading devices. Also, ink colors that will not image a photographic plate.

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 is not diluted by the other layer of wet ink.

Dry back
The color change that occurs when ink dries.

Dryer (drying oven)
Oven on a web offset press through which the web of printed paper passes after it leaves the final printing unit. The drying process, standard when heat-set inks are used, heats the web to about 350 degrees Fahrenheit.

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%.

Drying time
The time it takes for an ink to become rub- or tack-free.

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

Dummy
An unprinted, hand-folded mock-up of a book or brochure made prior to production using paper stock and exact specifications that will be used; also a type of proof.

Duotint
A one-color halftone printed over a screen of a second color halftone.

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

Duplex papers
Feature a different color on each side of the sheet, laminated together.

Duplexing
When paper is printed on both sides of the sheet.

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

Dylux
A stable print specially sensitized on two-sided papers for proofing.