In our business, it is a necessity to know basic paper and printing terms. Use the glossary for a quick reference or browse it to refresh your knowledge.
Select from the general listing below:
waffling
See fluting.
water fountain
See fountain.
water jet
See squirt.
waterless offset printing
Refers to lithographic printing, where no fountain solution is used. The non-image areas of the plate are composed of a material that serves the same function as the fountain solution, and does not "accept" the lithographic ink.
watermark
See dandy roll.
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. For this to occur, the sheets must be in a pile which prevents the center of the sheets from picking-up the same amount of moisture as the edges. This is caused by higher relative humidity of the air to which the paper is exposed. The waviness is usually more pronounced on the across grain edge (the edge perpendicular to the paper grain).
wax pick
A laboratory test, using a series of tack graded wax sticks (by Dennison) that when applied hot to a paper surface and lifted from the surface after cooling, provide an indication of surface strength: see picking. High wax pick numbers (over 10) are considered strong surfaces, and low numbers are weaker surfaces, on a scale of 2 to 25. Wax pick is used as a test on both coated and uncoated paper surfaces, but is considered a better measurement on uncoated paper.
weather wrinkles
Also called moisture welts or expansion wrinkles; are narrow raised welts or soft wrinkles around the outer diameter of a roll of paper. The phenomena usually occurs when a roll of paper absorbs moisture from the surrounding atmosphere, with a resultant increase in the paper fiber diameters and in the dimensions of the sheet in the across grain direction. The extra dimensions (usually beginning 6 to 8 inches from the edge of the roll where there is room for the extra dimensions to expand outward) give these raised areas. Weather wrinkles usually do not go more than 2 or 3 wraps down into the roll.
web
A continuous ribbon of paper, as from an unwinding roll.
web offset
A lithographic printing press in which the paper is fed from a roll as a web (continuous ribbon), as opposed to sheets. Paper requirements and ink drying mechanisms may differ between the two offset printing processes.
web press
A printing press that runs webs, regardless of printing method.
web tension
The amount of pull or tightness of pull applied to the paper in the direction of travel of a web.
wet end
The beginning of the paper machine, comprising the head box, wire, and wet presses; the first sections of the paper machine where the paper web is formed from water and the solid furnish components.
wet felt
Continuous fabric belts, used to support the wet paper web through the wet press section, and to carry away the water removed during the squeezing, "wringer" action of the wet press rolls. See also <i>felt</i>.
wet press
The second section of the paper machine, where water is "squeezed" from the still very wet, still forming web of paper. If the press is two bare wringer rolls, it is called a smoothing or smoother press.
wet rub
Resistance of a wet paper surface to scuffing and linting; also a test for the moisture resistance of a paper surface.
wet strength
Strength imparted by synthetic resins to paper, when that manufactured paper is subsequently exposed to extremes of water; paper is classified as wet strength if its ratio of wet to dry strength is 15% or more.
wet trapping
See trapping.
white light
The combination of all of the wavelengths of visible light (colors of the rainbow). See also <i>spectrum</i>.
white paper
See fine papers.
white water
Paper mill waters which have a white, cloudy appearance due to a fine dispersion of fibers and other paper making ingredients, picked up when separated from the furnish on the paper machine, washers, etc.
whitening
See milking.
wind
To separate sheets of paper, printed or unprinted, so that they will be ventilated by air. The purpose is to provide for easy separation in the next sheet feeding operation, or to allow volatile gases formed during drying of inks to escape and/or be replaced with fresh air; also called airing.
wire
The continuous open mesh material (earlier, a bronze or copper woven wire screen), used on the paper machine to initiate the water removal process; the wire is the traveling surface and primary forming mechanism of the paper web. When the wire is made of synthetics/plastics, it can also be called the fabric.
wire mark
The impression left in the paper surface by the wire on the paper machine; if observable, is usually the pattern of the mesh or coarse weave of the wire.
wire side
The bottom side of the web of paper, as it is produced on the paper machine; historically, has been the rougher of the two sides. See also <i>Fourdrinier</i>.
work and roll
See work and tumble.
work and tumble
Also called work and roll; printing the second side of a sheet of paper by turning the sheet over from gripper or lead edge to back or trailing edge, using the same guide side.
work and turn
Printing the second side of a sheet of paper by turning it over from left to right or right to left, using the same edge of the paper as the gripper or lead edge.
wove
Absence of a laid pattern.
wrap curl
See simple curl.
wrinkles
Creases or folds in the sheet, usually running at slight angles to the machine direction. They result from excess localized paper being forced through a nip, and their appearance will generally aid in identifying where the defect is created in the paper making, converting, or printing process. When printing, the wrinkles will occur in a direction at an angle to the sheet or web travel.
writing
The act of producing an image on a page one character or stroke at a time, such as by hand with a pen or pencil or by means of a typewriter or pen plotter.
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