Clicking a letter link will take you to the relevant section.
Single or multi-ply, loosely matted fiber sheet made from chemical pulp. Used in packaging, thermal and acoustical applications and as a cushioning medium.
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.
All types of used paper that provides a source of fiber for the manufacture of some papers, paperboards and chipboards. As defined by the EPA, it includes all postconsumer recovered materials as well as the preconsumer wastes which are manufacturing wastes such as envelope clipping, bindery wastes, rejected and unused paper from obsolete inventories, and printed paper which has never reached the consumer. This excludes mill broke, forestry by-products and fibers recovered from mill waste paper.
A paper with little or no sizing. Very absorbent.
The translucent design or name easily visible when a sheet is held to the light. A design is sewn onto the papermaking screen with raised wire. When the sheet is formed, the pulp settles in a thinner layer over the wire design. See dandy roll.
Quality of a sheet of paper to resist penetration by water from one surface to the other.
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).
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.
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.
Continuous sheet of paper produced and rolled up at full width used in web or rotary printing. Paper in roll form in any converting operation i.e., Web Offset. The continuous ribbon of paper, in its full width, during any stage of its progress through the paper machine. A continuous ribbon of paper, as from an unwinding roll.
A tear in a web roll during the printing process.
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.
A printing press that prints on rolls of paper passed through the press in one continuous piece, as opposed to sheets of paper. A printing press that runs webs, regardless of printing method.
The term given to the tension or pull exerted by the web press on the web roll. The amount of pull or tightness of pull applied to the paper in the direction of travel of a web.
Section of the head end of a paper machine. At the wet end, stock is fed in and much of water is eliminated by drainage, suction and press rollers, leaving a web of paper, which then passes through the drying cylinders. 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.
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 felt.
Paper machine consisting of a wire-covered cylinder rotating in a vat of pulpstock on which a mat of varying thickness is formed by drainage. These mats are removed either intermittently in thick sheets called laps or continuously.
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.
Resistance of a wet paper surface to scuffing and linting; also a test for the moisture resistance of a paper surface.
Resistance of a paper sheet to pull or stress produced by applied tension after it has become saturated with liquids. 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 STRENGTH PAPER
Paper where the fiber constitutes and/or the sheets are chemically treated to enhance their resistance to tearing, rupturing or disintegration after becoming saturated with liquids.
WET TENSILE STRENGTH
Resistance of a paper sheet to pull or stress produced by applied tension after is has become saturated with liquids.
A preferred archival adhesive for book arts.
The combination of all of the wavelengths of visible light (colors of the rainbow). See 11) spectrum.
Paper is perceived to be white due to high clarity, elevated diffusion and minimum perception of hues. It is related to the color of the sheet and actually is the equal presence of all colors. The extent that paper diffusely reflects light, of all wavelengths through the visible spectrum.
Any paper made from a pulp stock whose natural color has been corrected by the addition of blue, yellow and red dyestuff. To a printer, this term refers to any paper that is devoid of any printing material. See fine paper.
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.
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.
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.
Small impressions produced on the bottom surface of a sheet of paper caused by the mesh of the wire screen on which the wet web is formed in the wet end of a paper machine. 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.
The side of a sheet next to the wire in manufacturing; opposite from the felt or top side; usually not as smooth as the felt or top 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 Fourdrinier.
Paper made only from chemical pulp and free from wood-based impurities, such as lignin, which are present in mechanical pulp. Also known as free sheet.
Pulp obtained from wood.
WORK AND ROLL
See work and tumble.
WORK AND TUMBLE
Turning the sheet end over end and reversing the gripper edge between printing passes. 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
Turning the sheet and reversing the guide edge between printing passes (left to right). 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.
A paper finish with an even surface as distinct from the lined pattern of laid papers. Absence of a laid pattern.
Uncoated paper that has an even finish with a slight toothiness.
Papers which show no fine "laid" lines running through the sheet when held to the light.
Also called roll curl. See simple curl.
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.
Another name for bond paper.