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.


  • ACGIH
    Acceptable acronym for American Conference of Governmental Industrial Hygienists.
  • Achromatic color
    A neutral color (white, gray, or black that has no hue).
  • Achromatic color reproduction
    Color separation technique whereby the neutral compound is digitally replaced by a corresponding level of black; also refer to gray component replacement.
  • Achromatic lens
    A lens corrected for black and white photography; specifically one that brings visual rays to the same focus.
  • Acid
    Any substance in an aqueous solution capable of turning litmus indicator red, dissolving certain metals to form salts, reacting with base or alkali to form salt, below 7 pH.
  • Acid dye
    Textile printing color containing salts of organic acids and used for applying color to protein fibers such as silk, wool and polyamides.
  • Acid etching
    Producing images by using acid and resist materials.
  • Acid fixer (fix) (fixer) (fixing bath)
    A chemical solution containing sodium thiosulfate and diluted acetic acid that renders photographic images on film or paper permanent, upon immersion for the prescribed time by removing unexposed silver halides; also refer to hypo.
  • Acid free paper
    A paper with no acidity or residual acid producing chemicals.
  • Acid number
    A measure of the amount of free acid on a molecule, calculated as the number of milligrams of potassium hydroxide required to neutralize the free acids in one gram.
  • Acid proof (acid resistant)
    Quality of a material that prevents or lessens the effect of contact or immersion in acid.
  • Acid stop bath
    A photographic solution, generally acetic acid, used for stopping the action of the developer on a photographic positive, negative, film or paper.
  • Acid wash
    Chemical mechanical process where dye is taken out of a garment, producing a splotchy look that can range from large to a very fine; also referred to as rough cutting a garment.
  • ACL
    Acceptable acronym for applied color labeling.
  • ACL lug
    A small protrusion or depressed cavity manufactured in containers to act as a guide in positioning decorations; also refer to ramp.
  • Acquire
    Computer command, typically under "File" menu, that allows the start of scanning software directly from the application. Acquire is only available if the software is TWAIN-compliant.
  • Across grain
    A direction that is 90 degrees to the machine grain imposed in the making of paper from fiber; also refer to cross direction.
  • Acrylate
    An ester or salt coming from acrylic acid; a type of monomer used in UV ink and coating formulations that contains the chemical group CH2=CHCO2H.
  • Acrylic based adhesive
    A pressure sensitive adhesive based on acrylic polymers.
  • Acrylic emulsion
    A water based latex made with acrylic polymers used for coatings and/or impregnating.
  • Acrylic ink
    Ink containing acrylic polymers used for screen printing on some plastics and other substrates, especially where outdoor exposure is involved.
  • Acrylonitrile-butadiene-styrene (ABS)
    A thermoplastic derived from acrylonitrile, butadiene, and styrene, the strongest of the styrene copolymers and the most widely used.
  • Actinic light
    A ray of light that is composed of short wavelengths as found in the ultraviolet and violet areas of the spectrum; capable of changing the properties of photosensitive materials on exposure to the light source.
  • Activate
    To accelerate a reaction or increase chemical activity.
  • Activated carbon
    A powdered or granular carbon that is highly absorbent, used to remove organic vapors and odors.