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.


  • Flow rate
    Actual speed or velocity of the fluid movement.
  • Flowing-in
    Term describing the phenomenon of an ink running together after printing, obliterating much of the fine line resolution of the design being printed.
  • Flow-mark
    Excessive waviness in linear printed surface of ink or in a plastic material.
  • Fluff test
    Testing the amount of fibers which are loose or insufficiently bonded to various substrates such as paper, boxboard, and cartons.
  • Fluid medium
    The vehicle or liquid used in a suspension.
  • Fluid nozzle
    The part of a spray gun that meters and directs the liquid in an air stream.
  • Fluid ounce (fl oz)
    A US liquid measure equal to one-sixteenth of a pint or to 29.573 millimeters.
  • Fluidity
    The ease of flow of a material, measured in units of rhe; the greater the viscosity the less the fluidity.
  • Fluorescence
    The emission of electromagnetic radiation especially in the form of visible light by certain substances called phosphors, as a result of absorption of other radiations such as an electric discharge or an ultraviolet light.
  • Fluorescent
    A pigment which not only reflects a visible wavelength but is activated by most of the remaining absorbed light to re-emit it as color of a longer wavelength, which results in reinforcement of the reflected color.
  • Fluorescent exposing unit
    A self-contained unit consisting of a bank of fluorescent lamps of high actinic value for evenly exposing light sensitive materials such as photostencil film or emulsion, and a vacuum blanket for holding the stencil film or screen frame.
  • Fluorescent ink
    Ink formulated with pigments that are capable of absorbing energy in the blue or ultraviolet end of the spectrum and re-emitting it in the form of light in the visible wavelengths.
  • Fluorescent paper
    Paper that has light reflecting qualities, which is the direct result of optical bleaching additives in the form of fluorescent dyes making them whiter than white.
  • Fluorescent white
    (1) Colorless dyes or pigments which increase the business of paper by absorbing the UV energy and re-emitting it as visible light; (2) "White" paper containing fluorescent material.
  • Flush
    Refers to an object that is mounted directly to a surface, with no raised surface space between, i.e.: "Flush Mount Letters."
  • Flushing
    A method of transferring pigments from dispersions in water to dispersions in oil by displacement of the water by the oil.
  • Flutter
    The usually undeniable action of a paper or cardboard sheet activated by drafts of air when passing through a forced air drying system in which the sheet vibrates above the carrying belt.
  • Flux
    (1) A metal cleansing compound that chemically degreases and cleans metal preparatory to soldering; (2) In ceramic and glass decorating, a material that induces flow and adhesion in glazes; (3) A material or mixture that promotes fusion; (4) A form of low melting glass that forms the permanent vehicle in glass and ceramic enamel; refer to frit.
  • Fluxer
    A device for applying soldering flux.
  • Flying spot scanner
    Equipment in which the original is held inside a dark chamber, while a beam of light flies across it in a raster pattern.
  • FM (Frequency-Modulated Screening)
    A dithering method that uses uniform dot sizes and varies the distance between them. This method is different from conventional halftone screening, which aligns dots of varying sizes on a regular grid.
  • Foam board
    A family of rigid, foam centered sheet and boards, made of a variety of laminate materials.
  • Foaming agents
    Chemicals added to plastic and rubber that generate inert gases on heating, causing the resin to assume a cellular structure.
  • Focal distance
    The optimum distance between UV lamp/reflector and substrate for radiation curing.
  • Focal length
    (1) The distance from the optical center of the lens or mirror to the ground glass or film plane on which an object at infinity is in sharp focus; (2) The distance from the lens to the sensitized surface (film) when the lens is focused on an object at infinity distance.