Glossary Of Terms

The PRINTING United Alliance 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. PRINTING United Alliance 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 PRINTING United Alliance assumes no responsibility for the use of information presented herein.


  • Legging
    The stringing out of pressure sensitive adhesive when a material is drawn away from a substrate, its release liner, or its matrix.
  • Lehr
    A long tunnel shaped conveyorized oven for annealing and firing ceramic ink.
  • LEL
    Acceptable acronym for lower exposure limit.
  • Length
    The flow characteristics of a screen ink, often referred to as "long" or "short," but more often a screen ink will be short.
  • Leno weave
    A locking-type weave of silk bolting cloth that has twisted strands running in one direction with each twist encasing a single strand running in the crosswise direction; prevents the shifting of fibers in an open weave.
  • Lenox cut
    A continuous and precise sheeting method in which revolving steel disc slitters cut sides and rotating blades cut ends, for ream to ream accuracy of 0.397mm or 1/64 inch.
  • Lens
    One or more pieces of optical glass designed to collect and focus rays of light to form a sharp image on light-sensitive film, paper, or projection screen.
  • Lens aperture
    The adjustable opening in the iris diaphragm of a camera that determines the amount of light that will pass through the lens during exposure.
  • Lens axis
    An imaginary line drawn through the center of a lens from the front of the lens through the rear element.
  • Lens board
    Support that holds the lens in alignment with optical axis of a camera and allows it to move along that axis in connection with the reproduction percentage adjustment.
  • Lens speed
    The largest lens opening (smallest f-number) possible for a specific lens. (A fast lens transmits more light by way of a larger opening than a slow lens).
  • Lenticular
    A grooved plastic sheet with certain light properties that give a different visual angle at different light angles, creating a 3-dimensional effect when printed.
  • Letter A easel
    A version of the figure four easel that has the cross link located in a very low position.
  • Letter guide
    An adjustable mechanical lettering tool operated manually to produce lettering from guides, or templates.
  • Letterpress printing
    A process where ink is applied to paper or other substrate by means of relief (raised above the non-image areas) printing plate or type.
  • Letterscreen
    In printed circuit board manufacturing, a printing screen produced specifically for printing nomenclature.
  • Levelling
    (1) Process used to manufacture metal frames that are level across the frame dimension; (2) The smoothing out of a color application after it has been applied.
  • Levy screen (crossline or contact screen)
    A glass or plastic screen with very fine cross hatching rulings used for translating continuous tones into halftones.
  • Lexan
    Registered trademark of General Electric (GE) for polycarbonate film.
  • LIFO
    Acceptable acronym for last in, first out.
  • Lift
    A group of sheets cut or trimmed together.
  • Lift transfer
    A technique for making positives where an image printed on clay-coated paper is separated from the paper and transferred to a transparent or translucent plastic sheet.
  • Lifting
    The softening and penetration of a paint or ink layer by another ink film, the solvents of which cause wrinkling or raising of the first layer.
  • Ligature
    Letters that are joined together as a single unit of type such as fi, fl.
  • Light
    Electromagnetic energy in the 380 to 750 wavelength that affects vision.