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.


  • Focal plane
    A plane or surface on which a lens forms a correctly focused image.
  • Focus
    (1) Point at which rays of light meet after being reflected or refracted; (2) Adjustment of the distance setting on a lens to sharply define the subject.
  • Fogging
    Darkening or discoloring of a negative or photographic print.
  • Foil
    (1) A very thin metal sheet which can be used as a screen printing substrate, or in chemical milling, as a raw material for the production of miniature and sub-miniature metal parts, usually less than .006 inch (0.15 mm) in thickness; (2) Donor medium for thermal transfer printing.
  • Foil decoration
    Molding paper, textile, or plastic foil printed with compatible inks directly onto a plastic part, so that the foil is visible below the surface of the part as integral decoration.
  • Foil emboss
    The embossing of a substrate with the addition of foil.
  • Foil paper (foil laminate)
    A very thin metal sheet laminated to a paper backing or support sheet, usually with permanent adhesives for use as a single element substrate.
  • Foil stamping
    A mechanical process that results in the bonding of colored reflective material to a substrate.
  • Folding box easels
    A display part used for supporting merchandise in cardboard displays.
  • Folding box lock
    A type of lock arrangement commonly used to hold display segments made of lightweight stock.
  • Folding endurance (folding strength)
    The number of folds under specified conditions in a specified instrument which a specimen will withstand before failure. In the usual test, a specimen is subjected repeatedly to double folds through a wide angle while under tension.
  • Folio
    Page number.
  • Folio size
    A cut size paper greater than 27.9 x 43.2 cm (11 x 17 inches).
  • Font
    A complete assortment of type of one particular size and type face style.
  • Foot (ft)
    (1) A linear measure equal to 12 inches, one-third of a yard or 30.48 centimeters; (2) The bottom edge of a sheet.
  • Foot candle (lux)
    A unit for measuring the amount of light emitted by a source; one lumen per 9.290 square decimeters (square foot); a unit of illumination equivalent to that produced by a standard candle at the distance of 0.3048 meters (one foot).
  • Foot lambert (FL)
    A measure of brightness; one FL is the brightness exhibited by a white piece of paper, one foot away from a candle.
  • Footprint
    The edge of the squeegee which comes into contact with the screen mesh, usually no more than a few mils in width, and the length of which will equal the overall width of the squeegee blade. Rounded-edge squeegee blades will have a larger footprint than sharper ones.
  • Force drying (force air system)
    Any system of drying of screen printing inks, industrial coatings, or other materials by application of influences beyond normal atmospheric conditions, such as by forced air flow at ambient temperature or heated air.
  • Force travel curve
    The relationship between actuation force and switch travel expressed as a line switch.
  • Forced development
    Increasing the development of film to increase its effective speed (raising the ASA number for initial exposure), to compensate for low-light situations; also called push-processing.
  • Fork lock
    A simple lock for insertion of changeable display cards.
  • Formability
    The act of thermoforming without affecting the strength, flexibility or clarity of the material.
  • Format
    (1) The layout and physical appearance or arrangement of characters such as shape, size, type, and overall design of printed matter. (2) Characteristic identifying size of printer, media, or graphic, according to width of media roll, printer’s print area, or graphic. Medium Format is generally taken to be between 11"—24" in width; Large Format (Wide Format) larger than 24" in width, and Grand Format larger than 72" in width.
  • Forming
    Process of shaping rigid plastic into three-dimensional form by applying heat and pressure.