Glass Terminology

    1. Anneal: To prevent or remove objectionable stresses in glassware by controlled cooling.
    2. Binder (Fibrous Glass): Substances employed to bond or hold the fibers together.
    3. Blister: An imperfection a relatively large bubble or gaseous inclusion.
    4. Check: an imperfection; a surface crack in a glass article.
    5. Chill Mark: A wrinkled surface condition on glassware, resulting from uneven contact in the mold prior to forming.
    6. Chip: An imperfection due to breakage of a small fragment from an otherwise regular surface.
    7. Cord: An unattenuated glassy inclusion, possessing optical and other properties differing from those of the surrounding glass.
    8. Cullet: waste or broken glass, usually suitable as an addition to raw batch.
    9. Devitrification: Crystallization in glass.
    10. Dice: The more or less cubical fracture of tempered glass.
    11. Fiber: An individual filament made by attenuating molten glass. A continuous filament is a glass fiber of great or indefinite length. A staple fiber is a glass fiber or relatively short length (generally less than 44cm).
    12. Fusion: Joining by heating.
    13. Glass Ceramic: A material melted and formed as a glass, then converted largely to a crystalline form by processes of controlled devitrification.
    14. I.D.: Inside diameter.
    15. Lampworking: Forming glass articles from tubing and rod by heating in a glass flame.
    16. Lap: (1) An imperfection; a fold in the surface of a glass article caused by incorrect flow during forming. (2) A process used for mating ground surfaces.
    17. Liquidus Temperature: The maximum temperature at which equilibrium exists between molten glass and its primary crystalline phase.
    18. Mat (Fibrous Glass): A layer of intertwined fibers bonded with some resinous material or other adhesive.
    19. O.D.: Outside diameter.
    20. Out-of-Round: Asymmetry in round glass articles.
    21. Sealing: Joining by heating.
    22. Seed: An extremely small gaseous inclusion in glass.
    23. Softening Point: the temperature at which a uniform fiber, 0.5 to 1.0mm in diameter and 22.9 cm in length, elongates under its own weight at a rate of 1 mm per minute when the upper 10cm of its length is heated in a prescribed furnace at the rate of approximately 5ºC per minutes. For a glass of density near 2.5, this temperature corresponds to viscosity of 10 • 7.6 poises.
    24. Standard Taper: A two part number, 24/40, wtih 24 being the approximate diameter in millimeters at the large end of the taper and 40 the axial length of taper, also in millimeters.
    25. Stone: An imperfection; crystalline contamination in glass.
    26. Stria: A cord of low intensity generally of interest only in optical glass.
    27. Tempered Glass: Glass that has been rapidly cooled under rigorous control from near its softening point to increase its mechanical and stermal strength.
    28. Thermal Endurance: The relative ability of glassware to withstand thermal shock.
    29. Weathering: Attack of a glass surface by atmospheric elements.
    30. Working Range: The range of surface temperature in which glass is formed into ware in a specific process. The "upper end: refers to the temperature at which the glass is ready for working (generally corresponding to a viscosity of 10 •3 to 10 •4 poises), while the "lower end" refers to the temperature at which it is sufficiently viscous to hold its formed shape (generally corresponding to a viscosity greater than 10 •6 poises). For compartive purposes, when no specific process is considered, the working range of glass is assumed to correspond to a viscosity range from 10 •4 to 10 • 7.6 poises.


Information courtesy of CORNING

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