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:
packing
In printing presses, paper or other sheet materials used to underlay the plate and/ or blanket (between the cylinder and plate or blanket), to bring the surface of the plate or blanket to the desired height to obtain proper squeeze pressure for printing: can also be adjusted to compensate for minor dimensional changes in the paper in multipass, multicolor printing jobs, but only around the circumference of the cylinder (the print length).
padding compound
Also called edge padding glue or adhesive; A liquid adhesive mixture which when brushed or sprayed onto the side of a pile of paper adheres the sheets together along one edge, thus forming a pad.
paper
A relatively homogeneous matting of primarily cellulose fibers which are formed from a water suspension on the paper machine wire and bound together by entanglement of the fibers and by bonding agents, and subsequently dried.
paper machine
The machine upon which paper is produced from a suspension of cellulose fibers and other components in water (the furnish) by forming, pressing, drying, surface sizing (in some cases), calendering, and winding on a reel.
paper master
See paper plates.
paper plates
A plate for an offset duplicating printing press (offset lithography) made of paper: can be called a paper master or master.
papeterie
A wide variety of writing papers used for personal correspondence and greeting cards, with good sizing for pen and ink, with good opacity arid stiffness, and that fold well.
parchment
Originally a writing surface made from animal skins; today made from cellulose fiber paper by dipping unsized stock in sulfuric acid, to simulate the appearance and feel of genuine parchment; called "vegetable parchment" if made from cellulose fiber paper.
paste dryer/drier
In ink making, a type of dryer used in inks, usually a combination of dryer compounds. See also <i>dryers</i>.
paster
See splice.
paste-up
Assembled on one page for photographing the various art, display and text copy for a printing job; another term used is mechanical.
perfect binding
A Process of holding pages of a book together with glue (like padding), using no stitching or sewing. The backbones of the books are usually roughened, the adhesive applied, and finished with a wrap-around cover.
perfect/perfecting press
The terms apply to printing both sides of the paper in the same pass on the printing press. Also to print on the back of a sheet already printed on one side. Printing can be on opposite sides, either blanket-to-blanket or sequentially.
perforate
Punching a series of holes or slits in a line in the paper, to weaken it so tearing will occur easily along that line. Also the making of slits in paper during folding, at the fold, to prevent wrinkles and to allow air to escape.
perfs
The actual holes or slots created during perforating.
permanence
The resistance to paper to the destructive effects of age; also the archival properties of the paper or printed job. A lack of permanence is indicated by a significant loss in strength of the paper or a fade in the color or shades of the paper or printed image. The permanence of paper is chiefly dependent upon the purity of the cellulose used to make the paper, the acidity (see pH) in the paper as a result of manufacture or later contact, and the storage of the paper away from heat, light, and moisture.
personal computer
An electronic device, programmable to carry out a variety of functions, and intended primarily for use by one operator at a time.
pH
A scientific scale from 0 to 14, measured by instruments, and defining the strength of an acid or alkaline (basic) liquid. From 0 to 7 is acid - from 7 to 14 is alkaline, while 7 is considered "neutral", i.e., neither acid or alkaline.
photoconductor
See photoreceptor.
photoreceptor
The surface or plate in an electrostatic/xerographic copier or printer where the image and non-image areas are distinguished. The characteristic of a photoreceptor material is that it holds an electrostatic charge on its surface in the dark, and until the charge is dissipated or erased by exposure to light; when a material has this property with respect to electrostatic charges and light, it is known as a photoconductor. See also <i>electrostatic copier/printer</i>.
pica
See point.
picking
The lifting of any material off of, or out of, the paper surface during the printing impression; sometimes due to surface contamination, inadequate surface sizing, inadequate surface strength, or to the ink being too tacky. Generally, the pick will adhere to the blanket and interfere with future impressions; can appear to be hickeys in the printed surface. For measurement of picking see <i>I.G.T.</i> and <i>wax pick</i>.
pigment
1) Minerals and other materials used in the manufacture and coating of paper, to provide desired properties. 2) Minerals and other materials, including colorants, used in the manufacture of printing inks; finely divided solid materials.
piling
The collecting of ink particles upon rollers, blankets and plates, caused either by the inability of an ink vehicle to hold the ink pigment in suspension, or by microscopic pick and/or removal of pigment from the surface of the paper by the ink, and accumulating in the ink on the blanket, usually evidenced in the trailing edge of the image areas, resulting from extra thickness on the press blanket in the image area. If milking or whitening is severe enough, an accumulation of foreign material can occur in the nonimage areas, also creating an extra thickness there; this is also called non-image area "piling".
pinholes
Imperfections in paper which appear as minute holes upon looking through the sheet; accentuated by lower basis weights.
planographic printing
See offset lithography.
plate
Depending on the printing process, the means by which the image area is separated from the non-image area; the image carrier.
plate cylinder
The cylinder on the printing press around which the plate is mounted.
plate gap
See cylinder gap.
plybond
Internal bond strength, measure of the resistance of a sheet of paper to delaminate or blister, due to stresses created during printing and drying.
PMS color
An abbreviation for "Pantone Matching System"; an ink color system containing about 500 color swatches, each of which is identified by a color number and a formula for the ink.
poor splice
See splice.
poor start
Also called bad start; is when there is an obvious difference in the mechanical appearance between paper near the core and the remainder of the side of the roll.
porosity
A test which measures the time required for a given amount of air to flow through a sheet of paper; defines how open or tight the sheet of paper is with respect to the passage of air through the sheet.
porous printing
See <i>screen printing</i> and <i>mimeograph printing</i>.
portrait mode
A printer (usually driven by a computer) output orientation in which the printed lines run perpendicular to the direction of movement of paper. See also <i>landscape mode</i>.
press run
The quantity specified for any given printing job. Also, the number of impressions made from a printing plate.
press section
See wet press.
primary colors
The additive primary colors are the three major wavelengths of light in the visible spectrum: red, green and blue, and are used in applications such as the cathode ray tube of a color television set. The subtractive primary colors are used when dealing with reflected light, such as from a full color printed piece, and are yellow, magenta, and cyan. These are the three colors of ink used in process printing. In paper making, red, yellow, and blue are the primary colors in the dyeing of paper, any two of which can be mixed together to obtain secondary colors and hues (green, orange, and violet).
print contrast
A differential measurement of light reflectance between the image and background areas.
printing
The act of producing an image on a page from a machine designed for that purpose, such as a printing press or a computer printer like a laser or ink jet.
printing inks
Special coatings applied over specific areas of the paper surface by means of a printing press.
process inks/colors
Transparent inks used in three-color and four-color printing of full color pictures or drawings; subtractive primary ink colors are yellow, magenta, and cyan. See also <i>three-color process</i> and <i>four-color process</i>.
process printing
The printing from two or more halftone plates, to produce intermediate shades, hues, and tonal values. See also <i>three-color process</i> and <i>four-color process</i>.
proofs
Samples of copy and/or layout made at various stages of production of a printing job.
psychrometer
An instrument for determining the relative humidity of an atmosphere.
puffing
See fiber puffing.
pulping
The act of processing wood (or other plant) to obtain the primary raw material for making paper, usually cellulose fiber. Wood is the most widely used source of fibers for the paper making process. Chemical pulping is generally of the kraft or Sulfate process, the Soda process, or the Sulfite process - see each. Wood pulp can also be obtained for paper making by purely mechanical means ("groundwood") or in combination with chemicals or at elevated temperatures (see semi-chemical and thermomechanical pulp). See also <i>refiner mechanical pulp (RMP)</i>.
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