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.


  • Polyvinyl alcohol emulsion
    A solution made by dissolving specific amounts of a fine white synthetic powder known as polyvinyl alcohol and ammonium or potassium bichromate in specific volumes of water.
  • Polyvinyl fluoride (PVF)
    A polymer of vinyl fluoride (fluoroethylene), a monomer structurally similar to ethylene with a high melting point, chemical inertness and resistance to ultraviolet light.
  • Poplin
    Plain weave class of fabrics having fine cross ribs.
  • Porcelain
    A glazed or unglazed vitreous ceramic whiteware.
  • Porcelain process
    A method of producing glazed ware where a ceramic body and/or glaze are matured together in the same firing.
  • Porcelain sign
    A traditional type of metal sign utilizing porcelain enamel paints topped by a ceramic slip that is fired to create a durable glass like coating that is impervious to the environment.
  • Porosity
    The structure and density of a sheet; the ratio of the volume of the pores to the volume of the mass of a substrate.
  • Porosity percentage
    The percentage of the total volume of a material occupied by both open and closed pores.
  • Porous surfaces (porosity of substrate)
    Surface of substrate with open pore construction as in paper that have the capability of slight absorption, thus offering a mechanical bond with ink applications.
  • Portable Document Format (PDF)
    An electronic document format from Adobe that allows the distribution of digital files across any platform that can display a document as originally designed and formatted without having the software application or fonts on the viewing computer.
  • Portrait
    A page format that has greater height than width; page layout in vertical format.
  • Positionability
    The condition of a pressure sensitive product imposed during manufacture that permits repositioning after application.
  • Positive
    Film or vellum print where the light and dark areas appear as they do naturally, corresponding to the original copy.
  • Positive temperature coefficient
    An increase in resistance due to an increase in temperature.
  • Post cure
    (1) The continuation of a polymerization (curing) process within a UV ink or coating after exposure to UV radiation has been terminated; (2) A final or more complete resolving of organic materials after the initial curing process; (3) Additional elevated temperature cure, usually without pressure to improve final properties and complete the cure.
  • Post hardening
    Re-exposing a screen after it has been developed to fully harden the emulsion.
  • Post sensitizing
    A technique of coating stretched mesh with unsensitized emulsion and permitting the coat(s) to dry, then wiping the sensitizing solution onto both surfaces with a cotton pad under safe light conditions with a sensitizer just prior to use.
  • Poster
    (1) A message presented to public view to promote a product, event, civic action, etc., usually depending more on illustration for attraction than copy; (2) A very large sales promotion message screen printed in conveniently handled sections, for pasting up on outdoor poster boards.
  • Poster board
    A specific weight of cardboard beginning with caliper 0.024 (24 point). (Standard sheeted sizes are 559 x 711 mm (22 x 28 inches) and 711 x 1118 mm (28 x 44 inches).
  • Poster paper
    A name commonly used by printers for paper sheet material used in the printing of an outdoor advertising poster, usually wet-strengthened with opaque additives for minimum see-through when posted, rough on one side to facilitate pasting.
  • Poster plates
    A paper tissue stencil that is hand-cut and attached to the screen.
  • Posterization
    (1) A special effect performed on a piece of art that compresses all of the tonal values into a smaller range of tones usually not more than four; (2) A special effect created by using a limited number of gray levels within an image, computer created by setting a defined number of gradient steps in a bitmapped image.
  • PostScript
    A page description programming language created by Adobe. A device-independent industry standard for outputting documents and graphics.
  • PostScript point
    A slight revision to the "Point" measurement unit. A Postscript point is exactly 1/72 of an inch. Most graphics software utilizes this refined value for a point.
  • Potassium bichromate
    Orange red crystals sometimes used in the preparation of solutions for sensitizing carbon tissue, screen printing films, and coatings for screen printing stencils. (Bichromates are considered an environmental and health hazard and are no longer used in the industry).