Glossary of Paper Terms

Glossary of Paper Terms


Deterioration of part of image area on plate during printing.
Warm Color
Color of ink falling in the red-orange-yellow family.
Operation between ink/color changes. Time required between ink color changes.
Water Ball Roller
A roller which runs in the fountain solution pan.
Water Fountain
The metal trough on a lithographic press which holds the dampening solution.
Water in Ink
A press condition of too much water, which breaks down ink.
Water Resistance
Quality of a sheet of paper to resist penetration by water from one surface to the other.
Waterless Plate
In platemaking, printing on a press using special waterless plates and no dampening system.
A term referring to the impression of a design, pattern or symbol in a sheet while it is being formed on the paper machine wire. It appears in the finished sheet as either a lighter or darker area than the rest of the paper. Two types of watermarks are available. A shaded watermark is produced by a dandy roll located at or near the suction box on the Fourdrinier. The desired design is pressed into the wire covering the surface of the dandy roll similar to an intaglio engraving. As the wet pulp moves along the web the dandy roll presses down and creates an accumulation of fibers, thus the watermark is seen as being darker than the rest of the sheet.

The second type of watermark, called a wire mark, is accomplished by impressing a dandy roll with a raised surface pattern into the moving paper web in a similar manner to the shaded mark. This creates an area with less fiber making it lighter and more translucent.

Watermarks come in a variety of placement styles. Random, the least expensive to create, is a watermark that appears repetitively throughout the sheet in no particular order. A localized watermark is one that appears in a predetermined position on each sheet. Paraded watermarks appear in a line, either vertically or horizontally on each sheet. A staggered watermark pattern consists of several watermarks on each sheet in a predetermined fashion. (See dandy roll)
Characteristic of a pile of sheets when the outer edges retain more moisture from the air than the center does or when the center retains more moisture then the outer edges do. It is a form of paper curl.
Wavy Edges
A warping, "wave like" effect in paper which is the result of the edges of the sheet having picked up moisture and expanded to a larger size.
Roll of paper used in web or rotary presses and most often folded, pasted and converted in one continuous form. Also a ribbon of paper as it unwinds from a roll and threads through the press.
Web Break
Break in a roll of paper while it is on the machine during manufacturing or while on the printing press during production.
Web Offset Paper
Paper that is made to be printed in a continuous manner from a roll. It can be coated or uncoated and must be strong enough to withstand the rigors of web offset printing at high speeds.
Web Press
An offset press that uses web paper as opposed to sheet fed paper.
Web Tension
Amount of pull applied in direction of the travel of a web of paper by the action of a web-fed press.
Weight Tolerance
Acceptable degree of variation in a paper's shipped weight, usually within 5 percent of the paper's nominal weight.
Well-Closed Formation
Bonding of fibers in a sheet that provides an overall uniformity. Opposite of wild.
Hard sized.
Wet Rolls
Water or dampness on the edge of the roll can weld or bond the paper together, which will then break on the infeed, a problem easily determined by the press crew.
Wet Rub Test
A test of the moisture resistance of paper.
Wet Strength
The strength retained by a sheet when completely wetted with water; generally, tensile strength.
Wet-End -
Wet-End Finish
Category of finishes such as antique, eggshell, vellum applied to the wet paper web by machine rolls and the presses at the wet end of the papermaking machine.
Wet strength is measured most accurately as the percentage ratio of wet-tensile strength to dry-tensile strength. Example: a paper containing 30% wet strength actually possesses 30% of its original dry-tensile strength.
Wet-Strength Papers
Once wet, ordinary papers lose most of their original dry-strength properties. Wet strength papers possess properties that resist disintegration and rupture when saturated with water. Papers are classified wet strength when they retain 15% or more of their dry-tensile strength. Superior quality wet strength papers may retain as much as 50% or more dry strength following immersing in water. Wet strength papers range in weight from tissue to paperboard.
Wetting Agent
A material capable of lowering the surface tension of water and water solutions and increasing their wetting powers.
White Paper
A term often applied to printing and writing grade papers and envelopes.
Whiteness of pulp and paper is generally indicated by its brightness.
Water that has been used in the papermaking process that is milky in color.
(See Distributor)
Unit at the end of the paper machine that takes the paper web from the reel, trims it, winds it into rolls and slits it to make smaller rolls if desired.
At the wet end of the paper machine, a copper, bronze or synthetic screen that receives the suspension of water and fiber from the head-box. The wire moves the suspension along to the dry end of the machine. The wire terminates at the couch roll at which point the paper web is 90% water and can be transferred to the wet felt. In business forms, to stitch or fasten sheets to form a book or fastened set; may be side or saddle wired.
Wire Binding
A continuous double series of wire loops running through punched slots along the binding side of a booklet.
Wire Mark
On the bottom or wire side of the paper, these are impressed traces of the machine wire.
Wire Side
Opposite of felt side, this is the side of the paper that was against the wire during manufacture. A watermark will read backward from this side of the sheet.
With the Grain
Parallel to the direction in which the paper fibers lie.
Woodfree Pulp
Chemical pulp.
Work and Turn
To print one side of a sheet of paper then turn the sheet over from left to right and print the second side. The same gripper and plate are used for both sides.
Work and Tumble
To print one side of a sheet of paper, then turn it over from gripper to back using the same side guide and plate to print the second side.
Finish characterized by the impressions of a felt dandy roll covered in woven wire and without laid lines. ENVIRONMENT® Papers.
Wove Dandy
A dandy roll without a watermarked design.
(1) Creases in paper occurring during printing or folding. (2) In inks, the uneven surface formed during drying.
Writing Paper
A general term applied to papers used for writing purposes.
Wrong-Read Image
A mirror image such as that appearing on the blanket in offset printing.

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