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Specialty Graphic Imaging Association
SGIA Glossary

Definition Glossary

Sixth Edition

Language and our ideas about how it is interpreted change rapidly. The Specialty Graphic Imaging Association (SGIA) is aware of this and continues its effort to keep our constituents well informed about changes to the increasingly complex industry terminology. This publication represents the most recent changes.

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L/D ratio

Relationship between an extrusion screw length and its diameter.


An applied printed identification denoting contents, ownership, directions, destination, rating, or use.

label adhesion test

A method to determining the degree that a standard or designated label adhesive adheres to a surface under specific conditions.


Any of various clear or colored synthetic coatings made by dissolving nitrocellulose or other cellulose derivatives together with plasticizers and pigments in a mixture of volatile solvents used to impart a high gloss to a surface.

lacquer diluent

A fast dry strong solvency diluent used in lacquers and synthetic coating.

lacquer stencil

A photo-sensitive lacquer-like material laminated to a temporary support sheet.

lacquer thinner

blended solvent made up of a mixture of toluene, alcohol, ester, glycol ether and other solvents.

lacquered paper

Paper that has been coated with a lacquer or plastic.


The momentary time of contact of the printing screen to the substrate immediately after the printing stroke.

laid finish

Paper with a pattern of parallel lines at equal distances giving a ribbed effect.


A pigment made up of organic coloring matter with an inorganic base or carrier.


Adhesive used for combining and bonding films, foils, plastics, papers or other material in sheet or web form.

laminar flow

Air flow where essentially the entire body of air within a confined area moves with uniform velocity and direction as the ambient atmosphere being sampled.


(1) The act of adhere a film to a surface by hand or mechanical means to form a single multi-layer sheet; (2) A web or sheet material formed by bonding materials together.

laminating film

Usually a clear or transparent sheeting manufactured for use as a protective top strata of a cold seal or thermal lamination to processed material.

laminating press (laminator)

A device for producing a multi-layered sheet or for applying a protective sheet of clear plastic to a printed sheet or liner with pressure and heat or just pressure.


A sheet of material composed of two or more layers of material adhered together to form the sheet such as a liner and face material together with an adhesive to form a sheet of pressure sensitive label stock.


A light source.


A gray or black material made from soot obtained from the incomplete combustion of carbonaceous material used as a pigment to achieve a dull black ink with softer, grayer top tones and bluer undertones.


A page that has a greater width than height; page layout in horizontal format.

lap easel

An easel providing a rest for slanted lower parts of displays.

lap marks

The slight ridge produced by overlapping of colors, found especially in glass decorating where screen printed films are thicker than in usual commercial screen printing.

lapping colors (lap register)

Over-printing of the edges or other portions of the area of a printed color by a succeeding color.


Non-printed or blank space on edges of printed billboard poster paper used for joining and matching multiple sheets.


A printer, media, or print 24" or greater in width.


A high energy single wavelength pin-point light.

laser scanner

A device that uses color filters and beams of light to produce tone and color corrected separations for process printing.

latent charge

Electrostatic printing, the charge remaining in the area not exposed to light and dissipated.

latent curing

The use of a curing agent that is stable at room temperatures, but promotes a rapid cure at higher temperatures.

latent image

Invisible image on exposed film that has not been developed.

lateral reversal

Left to right or mirror image reversal.

layflat adhesive

An adhesive having the property of resistance to warping in laminations.


(1) A guide showing the arrangement and location of all type, illustrations, line art drawings, or sketches of a proposed printed piece; (2) The floor plan view of a printing plant or manufacturing area.


The fixed guides used to register a substrate on the printing bed.


The two sides of a sheet set against register guides (lays) for registration during screen printing.

lazy flame

A type of flame resulting from a gas rich mixture.