Glossary Of Terms

The SGIA Glossary of Terms serves as an excellent industry terminology resource. It is the language by which we all communicate, without it universal understanding would be impossible. Language and our ideas about how it is interpreted change rapidly. SGIA is aware of this and continues its effort to keep our constituents well informed about changes to the increasingly complex industry terminology. The definitions are for general reference only. Usage may vary between companies, individuals, or national and country customs. The information presented is as accurate as the authors and editors can ascertain and SGIA assumes no responsibility for the use of information presented herein.


  • L/D ratio
    Relationship between an extrusion screw length and its diameter.
  • Label
    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.
  • Lacquer
    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.
  • Lag
    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.
  • Lake
    A pigment made up of organic coloring matter with an inorganic base or carrier.
  • Laminant
    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.
  • Laminate
    (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.
  • Lamination
    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.
  • Lamp
    A light source.
  • Lampblack
    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.
  • Landscape
    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.
  • Laps
    Non-printed or blank space on edges of printed billboard poster paper used for joining and matching multiple sheets.
  • Large-format
    A printer, media, or print 24" or greater in width.