Basis Weight
Weight per a selected unit of area of a grade of paper; grammage or “grams per square meter” is used throughout the world and scientifically in the United States; the U.S. uses many different basis weight designations, depending upon the type of paper, including fine paper, but not limited to; lbs per 25'' x 38''-500 sheets: text, book, offset; lbs per 17'' x 22''-500 sheets: writing, bond, ledger; lbs per 20'' x 26''-500 sheets: cover; lbs per 24'' x 36''-500 sheets: newsprint, tag, tissue, board. The 500 sheets represent the standard “ream” count, and is the basic unit for determining area. Also called substance weight, particularly in the bond or business grades of paper.

Bulk
Measure of the density, or the thickness in relation to the basis weight of a sheet of paper: used in the binding of books and is measured as pages per inch (ppi). Individual sheet calipers do not necessarily total to ppi, because of how the sheets pack together.

Coated Paper
Paper which has been coated with a material to provide printing ink holdout, smoothness, and levelness.

Color Sequence or Ink Rotation
The order or sequence in which various colors of inks are printed; also laydown sequence. In multi-color printing, the trapping of each color down depends upon the lower tack of each successive color, i.e., jelly applied to peanut butter, not peanut butter applied to jelly.

Densitometer
Instrument used to measure the optical density of an image or color; optical density is the intensity of the color or printed image, usually (but not always) referenced to black and/or white.

Drawdown
The application (by a blade or a bar) of a thin film of coating or ink to a piece of paper, it is used as a test method for coating or ink characteristics (such as shade, color strength, coating strength, or other simulation testing).

Dry Back
The term applied when the density and/or gloss of the wet, freshly printed ink film decreases after drying, to a greater extent than was anticipated. It is generally related to an overly absorbent paper surface, or a poor ink-paper choice and match.

Dust
Loose particles of fibers, filler, or coating materials appearing on the edges of a skid, lift, or roll of paper; this dust can interfere with the quality of the printing, particularly if on the sheet or web surface.

Felt Side
The top side of the web paper, as it is produced on the paper machine; the side of a web paper produced on a on a paper machine opposite to the wire side; historically, has been the smoother of the two sides.

Fountain
The part of a printing press which contains the ink to be fed to the distributing system, and in offset lithography, the part that feeds the fountain solution to the dampening device/system; the latter also called the “water fountain”.

Holdout
(1)-In paper, the ability to resist surface liquid penetration. (2)-In printing, the property of the paper to have low ink absorption, allowing the ink to set on the surface with high gloss; can create set-off with direct printing.

Impression Cylinder
The cylinder against which an impression is made; used to create the pressure required to transfer the image from the blanket (or plate) to the paper surface.

Match Color
Premixed, semi or fully opaque printing inks used for exact color match, as in a corporate logo (examples: Coca-Cola® red or John Deere® green). Used in place of trying to match exact colors by the combination of 3 or 4 process colors. Can also add visual impact and reduce the process ink costs.

Mottle
Refers to the spotty, uneven or non-uniform appearance of either a printed surface (mostly in solid ink coverage areas),or to a non-uniform distribution of fibers in the formation of a sheet of paper.

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).

Plate
Depending on the printing process, the means by which the image area is separated from the non-image area; the image carrier.

Register
(1)-paper: a type of bond paper for multi-ply form use: i.e., register bond. (2)-Printing: when a design or form is printed in parts or steps, as in multiple colors, it is essential that all parts or inks lay down and match exactly. When they do, they are “in register” or in registration; otherwise, they are “out of register”.

Screen
The ruling (usually expressed as lines per inch, i.e., 120 lpi, 133 lpi, 150 lpi or dots per inch) used to determine the dots per unit area in developing tonal values in the printed piece. Up to the point of “dot gain”, the higher the screen, the finer the lines per inch, the greater the fineness of detail in the printed piece.

Scumming
A term describing the condition resulting when any non-image area of the plate tends to take ink (any cause); when this starts to occur in offset lithography, it is said that the plate is “catching up”, can also be called toning.

Show-through
The undesirable condition where the printing on the reverse side can be seen through the sheet under normal lighting.

Signature
A folded sheet of printed paper, usually a section of a book or magazine (or newspaper), ordinarily obtained by the folding of a single sheet into 4, 8, 16 or more pages. The term “signature” can also be applied to a printed flat sheet that is to be later folded into a multi-page document.

Stripping
(1)-In preparing lithographic plate making films, the placing of the negatives/positives in the proper place on the page. (2)-As a defect in lithographic printing, describes the condition when the ink rollers take water preferentially to the ink (the ink roller surface changes from oleophilic to hydrophilic). Usually occurs on metal ink rollers, but can occur in sythetic composition covered rollers.

Tack
Refers to the internal “stickiness” (cohesion) of an ink; a measurement of the resistance to splitting of an ink film between two separating surfaces; tack is necessary in lithographic inks to insure adequate film splitting at the thin ink film thickness necessary for this planographic process. High tack does stress the paper surface as the ink film is split from the blanket to the paper surface. If that film splitting stress is sufficient, the paper surface can be disrupted, with pick resulting. Tack is an ink characteristic that can be measured by instrumentation (such as with an inkometer); other ink fluid characteristics are described by “viscosity” and “length”.

Tooth
A term which implies a rough finish to the surface of a sheet of paper.

Touchplate
A single printing press plate added to accentuate a color, such as adding a second magenta, cyan, or even spot color ink to create such an accentuation. One such process developed by DuPont is called “Hi Fi” color, and uses up to 4 additional plates to enhance the original 4 color process printing, i.e., 4 colors and 4”touchplate”.

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.