Mar 10 2010

Glossary of Terms for
Paper and Printing

"G"

GAMPI

A bush found in the mountainous, warm areas of Japan. Gampi grows to 1.0 - 1.5 meters in height. It has been used as a washi-making material for many years due to the high quality of the fibre taken from the bark. The finished paper is somewhat translucent and has a shiny texture. Gampi cannot be cultivated and is therefore rare and the most expensive of these three materials

GATEFOLD

A four page insert to a book that is larger than the existing page dimensions, having a fold at the outer edge that serves as a hinge, allowing two sheets to fold out from the center to the edge. Also known as a foldout.

GELATIN

A sizing agent used to prevent inks from bleeding.

GHOSTING

A screening technique that entails scanning an image full-strength, then screening it back to reduce the dot size.

GLASSINE

A woodfree paper. Transparent, glazed and polished on both sides.

GLOSS

Specular reflection of light. Occurs when specular reflection exceeds the diffuse reflection from various viewing angles. Can be measured with various geometries of illumination. For most printing papers, gloss is measured at an angle of 75 to 85 degrees to a plane normal to the surface.

GLOSSY PAPER

Paper that has undergone advanced calendering on a supercalender. Steam and pressure are applied to burnish the paper and improve uniform reflection of light.

GRADE

A type or class of paper with the same composition and characteristics.

GRAIN

The direction in which most fibres lie in a sheet of paper. As the pulp slurry moves forward on the papermaking machine's forming wire, the fibres tend to align themselves in the direction of movement.

Binding books parallel to the grain allows for a smoother fold than working across the grain. Grain direction of sheetfed papers is usually indicated by underlining the number, such as, 23in x 35in.

On a web press, the grain direction should run along the length of the paper web.

GRAIN LONG (LONG GRAIN)

The grain of paper is parallel to the long dimension of a sheet of paper. E.g. 45 x 64cm., long grain, indicates that the grain is travelling in the 64cm direction.

GRAIN SHORT (SHORT GRAIN)

The grain of the paper is parallel to the short dimension of a sheet of paper, or at right angles to the long dimension. E.g. 64 x 45cm, short grain, indicates that the grain is travelling in the 45cm direction.

GRAMMAGE (GSM)

The term used to denote the weight of paper or board; the measurement used is the weight of a single sheet of one square metre, expressed as gramme per square metre (gsm). Grammes per square metre (GSM). Also denoted as gr/m2 or g/m2. The gramme weight of one square metre of a particular type of paper is a good comparative measure because it does not vary with sheet size.

GRAVURE

An intaglio, or recessed, method of printing that uses recessed images etched onto a flat or cylindrical plate which moves through an ink pool. A blade scrapes excess ink off the plate, leaving ink only in the recessed areas. A second cylinder presses the paper against the plate so that it picks up ink from the wells.

Gravure is ideally suited for multimillion copy runs because the presses can run at extremely high speeds, and the intaglio plates are more durable.

GREASEPROOF

Paper free of mechanical pulp, highly resistant to grease. Mainly used for the wrapping of greasy products.

GRIPPER EDGE

The leading edge of paper that moves through a printing press or folding machine. A 3/8" allowance in the paper must be made for the gripper edge.

GRIPPERS

A row of clips holding the sheet of paper in place as it speeds through the printing press.

GROUNDWOOD PULP

A mechanically prepared wood pulp used in the manufacturing of newsprint and publication papers. See Thermo-Mechanical Pulp.

GUILLOTINE

A French guillotine-style cutting machine that trims stacks of paper to size with a chopping downward movement.

GUTTER

The margin on a sheet which will be bound into a book or the gap between multiple images on a sheet.