Mar 10 2010

Glossary of Terms for
Paper and Printing

"W"

WALLET

An envelope with a square flap on the long edge.

WASHING

A method of rinsing residue from recovered pulp after it has been deinked.

WAT

A condition whereby a material is unaffected by water.

WATER FAST/RESISTANT

The ability to withstand the effects of water with minimal or acceptable levels of change.

WATER FINISH

High finish produced on paper or board as it passes through the calender stack by moistening either one or both sides with water.

WATER-BASED DYE INKS

Inks that are environmentally friendly with a great colour gamut.

WATERLEAF

Unsized paper which is very absorbent to ink.

WATERLESS PRINTING

A printing process that runs on offset lithography presses without the use of water. The non-image areas of the plate are coated with silicone so that ink can run off into shallow wells in the plate. Waterless printing supports finer dots and finely detailed images. A relatively new process, it is more expensive than traditional lithography.

WATERMARK

Designs impressed into paper while in course of manufacture by means of a projecting wire, on the mould.

A watermark design is etched onto a special plate in positive or negative form and attached to a cylinder called a dandy roll. As the wet pulp is being formed into paper, the dandy roll displaces the fibres slightly, causing the faint watermark design to appear on the paper.

Watermarks were employed as early as 1282. They served to identify the product of each paper mill and the designs chosen (many of them extremely complicated) also expressed emblematically the tenets of the manufacturers, which were handed down traditionally from father to son.

It was customary, and the custom has survived until the present day, for paper mills to use similar designs in common. These standard designs were triflingly modified by each individual maker; they have in many cases been the origin of modern terminology, such as Foolscap, Pott, Post and so forth.

WAVINESS

A form of paper curl resulting when the sheet edges in the pile absorb moisture that the centre of the pile cannot absorb; or the sheet edges surrendering moisture while the centre remains moist.

WAVY EDGES

Warping effect in paper that is the result of the edges of the sheet having picked up moisture and expanded. Will normally happen only in a pile that prevents the centre of the sheets from picking up the same amount of moisture and levelling out or cockling. It is usually a warm weather problem caused by improper balance between moisture content of the paper or too high humidity in the air.

WEB

The roll of paper that is used in web or rotary printing.

WEB BREAK

A tear through a roll of paper, either at the paper mill or on press. Web breaks can cause costly down time in production.

WEB PAPER

Designed for web presses, this paper comes in a roll rather than sheets and is folded and cut on press after it has been printed.

WEB PRESS

A printing press that prints on rolls of paper passed through the press in one continuous piece, as opposed to sheets of paper.

WEIGHT

The tonnage or poundage of a quantity of paper. Paper weight may be expressed as basis weight, ream weight, M weight or grammage.

WET END

The first stages of a papermaking machine before the drying process; at the wet end, stock is fed in and much of the high percentage of water is eliminated by drainage, suction and press rollers, leaving a web of paper which then passes to the drying cylinders.

WET STRENGTH

Papers to which this term applies retain an appreciable percentage of their mechanical strength after soaking in water, and are made by the addition of a resin to the stock during paper manufacture. This resin cements the fibres together and the bond tends to improve with age. The advantages of printing maps on, or making certain wrappings from, wet strength paper are obvious.

WET TRAP

Printing a layer of wet ink over or adjacent to a previous layer of wet ink.

WHITE LINED BOARD

A multi ply construction made predominantly from selected waste paper.

WHITENESS

The paper is perceived to be white due to high clarity, elevated diffusion and minimum perception of hues. It is a measure of the amount of light reflected from a sheet of paper. Paper that reflects more blue than red or yellow will have a cool, blue tinge and appear to be a brighter white than a warm tinged sheet.

WICKING

An inkjet output term for when ink is absorbed into paper media and then follows the grain of the paper.

WIRE SIDE

The bottom side of the paper that comes in contact with the forming wire of the papermaking machine. The top side of the paper is called the felt side. There can be a slight texture difference between the wire and felt sides.

WITH THE GRAIN

Folding or feeding paper into a press parallel to the grain of the paper.

WOODFREE

Paper made wholly from chemical pulp and free from wood-based impurities, such as lignin, which are present in mechanical pulp. Also known as Freesheet.

WOODPULP

Wood reduced to a pulp for subsequent papermaking processes; can be mechanical, chemical or combination; TMP and CTMP.

WORK AND TURN

The method of turning the sheet side-to-side after the first run so the same material can be printed on the back.

WORK-AND-BACK

The method of printing each sheet first on one side with one form, then on the other side with another form. This is also known as sheetwise.

WORK-AND-TUMBLE

The method of printing a sheet with the same pages on the front and back side. After the first run, the sheet is tumbled bottom to top and printed on the back side. When cut and folded, the sheet yields two or more finished pieces.

WOVE PAPER

Originally made with a finely woven wire screen to eliminate rib lines, today a wove surface is imparted using wet felts. It is a sheet with impressions in it formed by a dandy roll covered with woven wire. Wove papers are valued for their clothlike texture and smooth, even-sided finish.

WRITING GRADES

Papers that are ideal for business letterhead and personal stationery.

WRITING PAPER

Another name for bond paper.

WYSIWYG

What You See Is What You Get. The hypothetical condition in which it is alleged that what you see on the screen is what you get on the page.