The PRINTING United Alliance Glossary serves as an excellent industry terminology resource. It is the language by which we all communicate. Without it, universal understanding would be impossible.

To keep our constituents well informed about changes to the increasingly complex industry terminology, PRINTING United Alliance has developed this glossary of terms. 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.
  • Air permeability
    Relative ability of a material to permit air flow, or to breathe.
  • Air pollutant
    Dust, fumes, mist, smoke, and other particulate matter, vapor, gas, odorous substances, or any combination thereof.
  • Air pull
    Coating the ink over the screen without making an impression on the substrate; also refer to flood coat, flood stroke, flooding.
  • Air recovery
    A process of capturing airborne contaminants such as smoke, dust, and solvent vapors.
  • Air-dried pigment
    Pigment/resin combination capable of drying at room temperatures, with or without agitation of surrounding atmosphere by fan or other mechanical means.
  • Air-gas ratio
    Volume of air per unit volume of gas in a mixture supplied to a gas burner.
  • Alabaster glass
    A milky, white glass that diffuses light without fiery color.
  • Alcohol
    Any of a class of chemical compounds derived from hydrocarbon by replacing one or more of the hydrogen atoms with an equal number of hydroxyl radicals; a class of solvents that in addition to the hydrogen and carbon elements, also have oxygen, general formula C2H5OH.
  • Aliasing
    A visual stair stepping of image edges caused by too low of a resolution for the size of the output.
  • Alignment
    The act of aligning or the condition of being aligned; in typesetting, denotes the exactly even relationship at the top or bottom of letters of a font; can also refer to the setting of lines of type, so that their ends appear even, refer to justify.
  • Aliphatic hydrocarbon
    Commonly known as paraffins; a group of petroleum naphtha solvents that are straight chain or open chain hydrocarbons, such as petroleum ether, pentane, hexane, cyclohexane, mineral spirits, Stoddard solvent, kerosene, V M & P, mineral spirits, and lacquer diluents.
  • Aliphatic solvent
    A straight-chain solvent derived from petroleum of low KB (Kauri Butanol) value such as mineral spirits and Stoddard solvent.
  • Alkali
    Any chemical that reacts on contact with an acid; capable of neutralizing acids; pH greater than 7.
  • Alkali removable
    Resist ink, which when dry, are removable by application of a caustic compound or alkaline solution.
  • Alkali resistance
    The relative ability to resist the action of alkalis.
  • Alkali test
    Used to evaluate the resistance of printed labels to alkalis.
  • Alkaline dip
    Term used for that step in stripping or removing of an alkali soluble resist when an etched circuit board is dipped and soaked in a high strength (6-10%) solution of a sodium hydroxide, softening the resist which is subsequently removed in a separate water rinse.
  • Alkyd
    A group of synthetic resins formed by condensation of polybasic acids with polyhydric alcohols, modified with drying oils for printing ink manufacture.
  • Alkyd plastic
    Thermoset plastic based on resins composed principally of polymeric esters, where the recurring ester groups are an integral part of the main polymer chain, and where the ester groups occur in most cross links that may be present between chains.
  • Allergen
    A chemical to which an individual may be, or become, abnormally sensitive.
  • Alligator
    The effect of a surface film contracting during drying to form small, irregular islands of color somewhat resembling the texture of alligator skin, also referred to as orange peel.
  • All-over printing
    The technique of covering the entire front and/or front and back of a garment with a printed image.
  • Alpha
    (1) The average percent change in resistance per degree of a pure metal resistance device between 0 degrees and 100 degrees Centigrade, which is usually designated by the Greek letter A or a, with units of ohm/ohm/C; (2) The mask channel in a color system.
  • Alpha blending
    Ability to specify a fourth color component in addition to RGB, used to specify opacity, from completely transparent to opaque.
  • Alpha channel
    An eight-bit grayscale channel found in some graphics applications or the last eight bits in a 32-bit color scan. (The first 24 bits describe the color of objects. Alpha channels permit layering of images. Some uses include masking objects, making them transparent, or adding specific color instructions).