ASTM C162-23

Standard Terminology of Glass and Glass Products

General Information

• Status: Published
• Publication Date: 30-Sep-2023
• ICS: 01.040.81 - Glass and ceramics industries (Vocabularies)
• ICS: 81.040.01 - Glass in general
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.01 - Nomenclature and Definitions

Relations

• Replaces: ASTM C162-05(2015) - Standard Terminology of<brk type="line"/> Glass and Glass Products
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1376-21a - Standard Specification for Pyrolytic and Vacuum Deposition Coatings on Flat Glass
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1322-15(2019) - Standard Practice for Fractography and Characterization of Fracture Origins in Advanced Ceramics
• Effective Date: 01-Oct-2023
• Referred By: ASTM E2875/E2875M-12(2021) - Standard Guide for Personal Protective Equipment for the Handling of Flat Glass
• Effective Date: 01-Oct-2023
• Referred By: ASTM F2179-20 - Standard Specification for Annealed Soda-Lime-Silicate Glass Containers That Are Produced for Use as Candle Containers
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1651-11(2018) - Standard Test Method for Measurement of Roll Wave Optical Distortion in Heat-Treated Flat Glass
• Effective Date: 01-Oct-2023
• Referred By: ASTM C148-17(2022) - Standard Test Methods for Polariscopic Examination of Glass Containers
• Effective Date: 01-Oct-2023
• Referred By: ASTM E2649-20 - Standard Test Method for Determining Argon Concentration in Sealed Insulating Glass Units Using Spark Emission Spectroscopy
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1285-21 - Standard Test Methods for Determining Chemical Durability of Nuclear, Hazardous, and Mixed Waste Glasses and Multiphase Glass Ceramics: The Product Consistency Test (PCT)
• Effective Date: 01-Oct-2023
• Referred By: ASTM C829-81(2022) - Standard Practices for Measurement of Liquidus Temperature of Glass by the Gradient Furnace Method
• Effective Date: 01-Oct-2023
• Referred By: ASTM E1732-22 - Standard Terminology Relating to Forensic Science
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1172-19 - Standard Specification for Laminated Architectural Flat Glass
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1426-14(2020) - Standard Practices for Verification and Calibration of Polarimeters
• Effective Date: 01-Oct-2023
• Referred By: ASTM C1663-18 - Standard Test Method for Measuring Waste Glass or Glass Ceramic Durability by Vapor Hydration Test
• Effective Date: 01-Oct-2023
• Referred By: ASTM E2189-19 - Standard Test Method for Testing Resistance to Fogging in Insulating Glass Units
• Effective Date: 01-Oct-2023

Overview

ASTM C162-23: Standard Terminology of Glass and Glass Products provides authoritative definitions of terms commonly used within ASTM's C14 series of glass standards and the broader glass industry. By establishing consistent language, this terminology standard supports clear communication and understanding between manufacturers, suppliers, architects, engineers, and regulators involved in the design, production, testing, and specification of glass and glass products.

This standard, maintained by ASTM Committee C14, includes both current and historical glass terminology, clarifies industry-specific usages, and references additional glossaries from organizations such as the Glass Association of North America (GANA) and the National Glass Association (NGA). Definitions are updated as technologies evolve, with each revision reflecting changes in usage and technical development in the glass sector.

Key Topics

• Core Glass Terminology: Definitions of fundamental terms such as annealed glass, tempered glass, laminated glass, optical properties (e.g., Abbé value), and various types of glass (e.g., borosilicate, flint, float glass).
• Manufacturing Processes: Explanation of forming, finishing, annealing, tempering, glazing, and other methods used in glass manufacture and fabrication.
• Imperfections and Defects: Standardized names for imperfections (e.g., blister, chip, crizzle, fracture mirror), supporting uniform reporting and quality assessment.
• Testing Methods: Reference to ASTM test procedures for properties like annealing point, softening point, contamination, and stress patterns.
• Industry-Specific Lexicon: Inclusion of archaic, specialty, and regionally distinct terms to aid industries such as construction, optics, and container manufacturing.
• Physical and Chemical Properties: Description of key properties such as refractive index, chemical durability, bending stress, dispersion, and emissivity.
• Related Equipment and Components: Glossary of tools, furnace configurations, forming devices, and standard glassware components.

Applications

ASTM C162-23 plays a vital role in:

• Technical Specifications: Enabling precise specification of glass products for architectural projects, safety glazing, optics, containers, and specialty applications.
• Quality Control: Standardizing terminology for describing test results, defects, and process requirements across the entire supply chain.
• Training and Reference: Serving as an educational resource for professionals entering the glass industry or seeking to maintain compliance and up-to-date knowledge.
• Design and Engineering: Assisting architects, engineers, and designers to accurately describe performance expectations, glass types, and finish requirements.
• Procurement and Compliance: Ensuring contract documents, material submittals, and inspection reports use common, defined industry language, reducing ambiguity and project risk.

Related Standards

Several ASTM standards are referenced within ASTM C162-23 and often used in conjunction:

• ASTM C148: Test Methods for Polariscopic Examination of Glass Containers
• ASTM C336: Test Method for Annealing Point and Strain Point of Glass by Fiber Elongation
• ASTM C338: Test Method for Softening Point of Glass
• ASTM C598: Test Method for Annealing Point and Strain Point of Glass by Beam Bending
• ASTM C813: Test Method for Hydrophobic Contamination on Glass
• ASTM C1048: Specification for Heat-Strengthened and Fully Tempered Flat Glass
• ASTM C1172: Specification for Laminated Architectural Flat Glass

Additional glossaries from GANA and NGA supplement the definitions in this standard for specialized applications.

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ASTM C162-23 is essential for anyone working with glass and glass products, providing the vocabulary necessary for clear, accurate communication and effective application of glass standards worldwide. For the latest official version and comprehensive definitions, users should consult the ASTM website.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C162 − 23
Standard Terminology of
Glass and Glass Products
This standard is issued under the fixed designation C162; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Abbe´ value 5 ~n 2 1!/~n 2 n !
d F C
where n is the refractive index for the helium line at
d
1.1 This terminology defines terms generally used in C14
587.6 nm and n and n are the refractive indices for the
F C
standards with related additional terms from the glass industry.
hydrogen lines at 486.1 nm and 656.3 nm, respectively. See
synonymous term nu-value and related term dispersion.
1.2 In some cases in which a usage is specific to a certain
industry, that is spelled out within the definition. For complete-
abraded—describes a test specimen that has at least a portion
ness and historical purposes, terms that are outdated are listed
of the area under test subjected to an operationally defined
as being archaic. The reader is cautioned that some companies
procedure for mechanical abrasion. The severity and unifor-
or industries may define or use terms differently than the way
mity of abrasion should be sufficient to ensure origin of
these terms are defined within this terminology.
failure substantially in the region of maximum stress.
1.3 Other sources of glass glossaries are National Glass
absorption—a magnitude reduction of electromagnetic energy
Association’s GANA Glazing Manual, NGA Engineering Stan-
2 of neither transmission nor reflection, such as sunlight being
dards Manual for Tempered Glass, Laminated Glass Design
2 absorbed by tinted glass.
Guide, and ASTM Committee C-14 standards.
acid polishing—the polishing of a glass surface by acid
2. Referenced Documents
treatment.
2.1 ASTM Standards:
acoustics—the science of sound and sound control.
C148 Test Methods for Polariscopic Examination of Glass
Containers
air bells—bubbles of irregular shape formed generally during
C336 Test Method for Annealing Point and Strain Point of
the pressing or molding operations in the manufacture of
Glass by Fiber Elongation
optical glass.
C338 Test Method for Softening Point of Glass
C598 Test Method for Annealing Point and Strain Point of alabaster glass—a milky-white glass that diffuses light with-
Glass by Beam Bending
out fiery color.
C813 Test Method for Hydrophobic Contamination on Glass
alcove—a narrow channel to convey molten glass from refiner
by Contact Angle Measurement
to forehearth or to the revolving pot where it is gathered by
C1048 Specification for Heat-Strengthened and Fully Tem-
the Owens machine.
pered Flat Glass
C1172 Specification for Laminated Architectural Flat Glass
alkali—an industrial term for the oxide of sodium or potas-
sium; less frequently of lithium.
3. Terminology
ampoule—a glass container designed to be filled and sealed by
Abbé value—the reciprocal dispersive power, a value used in
fusion of the glass neck.
optical design, expressed mathematically as:
analyzer—a polarizing element, typically positioned between
This terminology is under the jurisdiction of ASTM Committee C14 on Glass the specimen being evaluated and the viewer.
and Glass Products and is the direct responsibility of Subcommittee C14.01 on
Nomenclature and Definitions.
anisotropy—a strain pattern inherent in all heat-strengthened
Current edition approved Oct. 1, 2023. Published December 2023. Originally
and fully tempered glass. This strain pattern may be visible
approved in 1941. Last previous edition approved in 2015 as C162 – 05 (2015).
under certain lighting conditions. It is a characteristic of
DOI: 10.1520/C0162-23.
heat-treated glass and should not be mistaken as
Available from National Glass Association (NGA), 344 Maple Ave. West, Unit
272, Vienna, VA 22180. http://www.glass.org.
discoloration, nonuniform tint or color, or a defect in the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
glass. The strain pattern does not affect any physical prop-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
erties or performance values of the glass. Also known as
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. iridescence.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C162 − 23
anneal—to attain acceptably low stresses, or desired structure, bait—the tool dipped into molten glass to start any drawing
or both, in glass by controlled cooling from a suitable operation.
temperature.
barrel, glass container—{archaic} see sidewall, glass con-
annealed glass—describes glass subjected to the annealing
tainer.
process.
base—{archaic} the bottom of a bottle.
annealing—a controlled cooling process for glass designed to
basic fiber—unprocessed glass fibers directly from the form-
reduce residual stress to a commercially acceptable level and
ing equipment.
modify structure.
batch—(1) the recipe of batch ingredients.
annealing lehr—an on-line, controlled heating/cooling appa-
(2) the raw materials weighed but unmixed.
ratus located after the glass is formed and before the glass is
(3) the raw materials, properly proportioned and mixed, for
cooled. Its purpose is to anneal the glass product.
delivery to the furnace.
annealing point (A.P.)—that temperature corresponding either
batch charger—a mechanical device for introducing batch to
to a specific rate of elongation of a glass fiber when
the glass melting furnace.
measured by Test Method C336, or a specific rate of
midpoint deflection of a glass beam when measured by Test
batch feeder—see batch charger.
Method C598. At the annealing point of glass, internal
stresses are substantially relieved in a matter of minutes.
batch house—the place where batch materials are received,
handled, weighed, and mixed.
annealing range—the range of glass temperature in which
stress in glass can be relieved at a commercially practical
bath—synonymous with float bath.
rate. For purposes of comparing glasses, the annealing range
bead—(1) an enlarged, rounded raised section on a glass
is assumed to correspond with the temperature between the
article.
annealing point (A.P.) and the strain point (St.P.)
(2) a small piece of glass tubing bonded around a wire lead.
antimony—an industrial term for an oxide of antimony.
(3) in fiber glass, a tear drop-shaped glass mass which forms
as a result of the interruption of the fiber forming process
applied color label (ACL)—a ceramic-glass enamel/ink ap-
below an orifice.
plied to and fired on a glass surface for the purposes of
decoration and labeling. Also called Applied Ceramic Label.
beam bending viscometer—a device used to determine the
viscosity of glass by viscous bending of a loaded beam.
arch, n—a part of a glass melting furnace; a crown.
bearer arch—see rider arch.
arch, v—to heat a pot in a pot arch.
bearing surface—the outside surface of an item of glassware
architectural glass, n—a general term applied to glass used in
on which it rests when in its normal upright position.
the building industry.
beltmarks—see chain marks.
arrest mark—see dwell mark.
bench—see siege.
arsenic—an industrial term for an oxide of arsenic.
autoclave—a vessel that employs pressure and heat, used to bending stress—a continuously and linearly changing stress
across the thickness of a glass body, varying from compres-
produce a permanent bond between glass and interlayers
suitable for this process, creating a laminated glass product. sion on one surface to tension on the opposite surface.
bent glass—previously flat glass that has been configured in an
aventurine—{archaic} glass containing colored, opaque
spangles of non-glassy material. out-of-plane manner by a method such as heating followed
by cooling into a new self-sustaining form, or the application
back wall—the wall at the charging end of a glass melting
of external sustained load.
furnace.
beveling—the process of edge finishing flat glass to a beveled
baffle—a mold part used to close the delivery or baffle hole in
angle.
a blank mold.
bicheroux process—{archaic} an intermittent process for
baffle mark—a mark or seam on a bottle resulting from a mold
making plate glass, in which the glass is cast between rolls,
joint between blank mold and baffle.
onto driven conveyer rolls, or a flat moving table.
baffle wall—a wall used to deflect gases or flames in a glass
binder—(1) for a continuous filament process, a constituent of
melting furnace.
a fiber glass sizing that couples the fiber to the composite
See shadow wall.
matrix.
baghouse—a chamber containing bag filters for the removal of (2) for insulation, material applied to glass fibers to hold
particles from a process exhaust stream. them in a desired arrangement.
C162 − 23
bite—the dimension by which the framing system overlaps the blow mold—the metal mold in which a blown glass article is
edge of the glazing infill. finally shaped.
body—the attribute of molten glass, associated with viscosity
blank—(1) a preliminary shape from which a finished article is
further formed, molded, or cut. and homogeneity, which is conducive to workability.
(2) a semi-finished piece of glass for making an optical
boil—turbulence caused by gases escaping from the melting
element, such as a lens or prism. Also known as a pressing.
batch.
blank mold—the metal mold that first shapes the glass in the
boil (bubble)—in laminated glass, a gas pocket in the inter-
manufacture of hollow ware.
layer material or between the glass and the interlayer.
blanket feed—a method for charging batch designed to
boost melting—see electric boosting.
produce an even distribution of batch across the width of the
glass melting furnace.
boot—a suspended enclosure in the nose of a glass melting
furnace protecting a portion of the surface and serving as a
blending-batch—{archaic} stepwise changes in batch compo-
gathering opening.
sition to arrive at the final change in finished glass.
borax glass—vitreous anhydrous sodium tetraborate
blister—a relatively large gaseous inclusion in glass.
(Na B O ).
2 4 7
bloach—{archaic} an imperfection resulting from incom-
borosilicate glass—a silicate glass with B O content above 4
2 3
pletely grinding plate glass, caused by a low place in the
weight percent, characterized by a moderate to low thermal
plate which retains part of the original rough surface.
expansion, long in viscosity versus temperature, and low in
density.
blocking—(1) shaping a gather of glass in a cavity of wood or
metal.
bow—a condition in which a lite of flat glass departs from a
(2) archaic, promoting mixing and fining of glass by
true plane.
immersion of a wooden block or other object to create
bubbles.
bowl—see spout.
(3) reprocessing to remove surface imperfections.
breast wall—(1) the entire side wall of a glass melting furnace
(4) archaic, mounting of glass for grinding and polishing.
between the flux block and the crown, but not including the
(5 ) archaic, idling a furnace at reduced temperatures.
ends.
See hot hold.
(2) refractory wall between pillars of a pot furnace and in
block mold—a one-piece mold.
front of or surrounding the front of a pot.
block reek, rake—{archaic} a scratch imperfection caused by
breezing—{archaic} buckwheat anthracite coal or coarse sand
cullet lodged in the felt in the polishing operation.
spread on the siege before setting of pots.
bloom—(1) a visible surface film resulting from attack by the
bridge—the structure formed by the end walls of the adjacent
atmosphere or from the deposition of particulate or vapor
melter and refiner compartments of a melting furnace and the
condensates. (See also smoked.)
covers spanning the gap between the end walls.
(2) a blemish in float glass appearing on the bottom (tin
bridge cover—see bridge wall cover.
contact) surface after reheating as a result of the presence of
tin diffused into the surface.
bridge wall cover—refractory blocks spanning the space
between the bridge walls.
blow-and-blow process—the process of forming hollow ware
in which both the preliminary and final shapes are formed by
bridgewall—that part of a glass melting furnace forming a
air pressure.
bridge or separation between melter and refiner.
blower—one who forms glass by blowing. (See also gaffer.)
bruise—synonymous with percussion cone.
blow head—part of a forming machine serving to introduce air
bulb edge—the heavy rounded edge or bead of glass, for
under pressure to blow any hollow glass article.
example, the extreme lateral edge of the ribbon of flat glass
as drawn.
blow-over—the thin-walled bubble formed above a blow mold
in hand-shop operation to facilitate bursting-off.
bull’s eye—(1) a tempered solid cylindrical sight glass.
(2) the glass left by the punty in the center of a flat disk of
blowpipe—the pipe used by a glassmaker for gathering and
glass made by the hand blown crown process.
blowing by mouth.
(3) in flat glass, an optical distortion that arises from a
blowing iron—see blowpipe. polishing depression or a solid inclusion trapped between
layers of laminated glass.
blown glass—glassware shaped by air pressure, as by com-
pressed air or by mouth blowing. bump check—see percussion cone.
C162 − 23
burner block—a refractory block with one or more orifices ceramic glass enamel (also ceramic enamel or glass
through which fuel is admitted to a furnace. enamel)—a functional and/or a decorative, usually colored,
coating for bonding to glass at melt temperatures typically
burn-off—the process of severing an unwanted portion of a
composed of glass frit, inorganic pigments and an organic
glass article by fusing the glass.
medium.
burnt lime—calcined limestone (CaO · MgO, dolomitic), or
chain marks—marks made on the bottoms of glass articles as
CaO (calcitic), or a mixture of these.
they ride through a lehr on a chain belt.
bursting-off—the breaking of the blowover.
channel—(1) in container glass, that part of a forehearth which
bushing—(1) a liner in the feeder orifice for molten glass.
carries the glass from the melter to the flow spout and in
(2) a precious metal or refractory/metal structure with single
which temperature adjustments are made.
or multiple hole(s) through which glass flows and is attenu-
(2) in fiber glass, the structure to deliver glass from the
ated into fiber(s).
melter to the refiner or forehearth.
butterfly bruise—see percussion cone.
charge, n—see batch (3).
cabal glass—a glass consisting primarily of the oxides of
charge, v—to add batch to a glass melting furnace.
calcium, boron, and aluminum.
chatter sleek—{archaic} see frictive track.
campaign—the working life of a melting furnace between
major cold repairs.
check—an imperfection; a surface crack in a glass article.
canal—that part of a melting furnace leading from the fining
checkers—(1) an open structure of firebrick serving as a heat
area to the forming area. See channel and forehearth.
exchanger.
(2) slang for regenerators of this type.
cane—solid glass rods.
(3) slang for refractory brick used in such a construction.
cap, n—(1) another name for crown.
chemical durability—the lasting quality (both physical and
(2) a type of bottle closure.
chemical) of a glass surface. It is frequently evaluated, after
cap, v—{archaic} to cut off the ends of a glass cylinder.
prolonged weathering or storing, in terms of chemical and
physical changes in the glass surface, or in terms of changes
carnival glass—glass having an iridescent coloration obtained
in the contents of a vessel.
by firing metallic salts applied onto a colored glass body. See
lusters.
chemical vapor deposition (CVD)—a process in which a
gaseous chemical mixture is brought in contact with the hot
carry-in—manual lehr loading.
glass substrate and a pyrolytic reaction occurs at the surface
cased glass—glassware whose surface layer has a different
of the substrate leading to the deposition of a coating which
composition from that of the main glass body.
bonds to the glass.
casehardened—a term sometimes used for tempered glass.
chemically strengthen—conducting ion exchange of constitu-
(See tempered glass.)
ent alkali ions in a glass product by immersing it in a bath of
molten salt containing larger alkali ions. Penetration of the
cast glass—glass cooled in the pot in which it was melted.
larger ions into smaller host sites produces a layer of
casting—a process of shaping glass by pouring molten glass
compression on the surface which strengthens the glass.
into molds.
chemically strengthened glass—glass that has been strength-
cat eye—an imperfection; an elongated bubble containing a
ened by ion-exchange to produce a compressive stress layer
piece of foreign matter.
at the treated surface.
cat scratch—streak(s) on the surface of glass containers which
chill mark—a wrinkled surface condition on glassware result-
has a slightly different chemical composition than the base
ing from uneven cooling in the forming process.
glass typically resulting from refractory dissolution by
molten glass and resembling the marks of a cat’s claws. Also
chip—an imperfection due to breakage of a small fragment out
referred to as “surface cord”, “mare’s tail”, or “feeder
of an otherwise regular surface.
streak”.
chipped glass—a decorative glass article with chipped surface
centering—an operation on lens elements wherein the element
produced intentionally.
is optically aligned with the axis of rotation and the edges
chipping—the process of removing thin extra glass prior to
ground concentric with the optical axis.
grinding.
ceramic glass decorations—ceramic glass enamels applied to
and fused to glass at the enamel melt temperatures to choke—an imperfection consisting of an insufficient opening
produce a decoration. in the finish and neck of a container.
C162 − 23
chopped fiber—fiber glass strand which has been chopped to Crookes glass—a glass having low transmission for ultraviolet
specified lengths. light, and containing cerium and other rare earths.
cross-fired furnace—see side-fired furnace.
chunk glass—{archaic} optical glass obtained in breaking
open a pot of transfer glass.
crown—the top or roof of a glass melting furnace.
cleavage crack—damage produced by the translation of a
crown optical glass—see optical crown glass.
hard, sharp object across a glass surface. This fracture
crown process—{archaic} a method of making flat glass by
system typically includes a plastically deformed groove on
blowing a large bulb, opening it, and then spinning it flat.
the damaged surface, together with median and lateral cracks
emanating from this groove.
crush—pitted condition with a dull appearance.
Colburn sheet process—{archaic} manufacture of sheet glass
crystal glass—(1) colorless, highly transparent glass which is
by bending the vertically drawn sheet over a roll which
frequently used for art or tableware.
establishes the definition of draw.
(2) colorless, highly transparent glass historically containing
lead oxide.
cold top melter—an all electric melting furnace in which a
thermally insulating layer of batch is maintained on top of
cullet—a collection of broken glass that may be processed and
the molten glass.
sorted based on color and/or chemistry. It may be reintro-
duced as an essential ingredient in the raw batch in glass
compact—to treat glass in a manner, such as by heat treatment,
making to facilitate melting.
to approach maximum density.
cullet cut—synonymous with block reek.
contact stress—the tensile stress component imposed at a
cut glass—glassware decorated by grinding figures or patterns
glass surface immediately surrounding the contact area
on its surface by abrasive means, followed by polishing.
between the glass surface and an object generating a locally
applied force.
cut-off scar—a mark on the base of a glass bottle caused by the
cutting of the gob in the Owens process.
continuous filament—a single glass fiber of sufficiently small
diameter to be flexible enough for textile uses and of great or
cut size—glass ordered cut to its final intended size.
indefinite length.
cutting—scoring glass with a diamond, steel wheel, or other
continuous furnace—synonymous with glass melting furnace.
hard alloy wheel and breaking it along the score. Other
methods of cutting glass include water jet and laser.
cooling-down period—{archaic} (1) the time elapsing after a
covered pot is opened before the glass is cool enough to
cycle—the firing period in a regenerative furnace.
work.
cylinder process—{archaic} manufacture of window glass
(2) period between fining stage and the removal of the glass
wherein molten glass is blown and drawn into the form of a
from the furnace.
cylinder, which is subsequently split longitudinally, reheated
cooling rate—see setting rate. in a flattening kiln, and flattened.
Danner process—a mechanical process for continuously
cord—an attenuated glassy inclusion possessing optical and
drawing glass cane or tubing from a rotating mandrel.
other properties differing from those of the surrounding
glass.
day tank—a periodic melting unit, which supplies glass for
small volume applications.
corrugated glass—glass rolled to produce a corrugated con-
tour.
dead anneal—jargon for a state of negligible residual stress.
crack-off—the process of severing a glass article by breaking,
dead plate—in automatic production of molded glass, a
as by scratching and then heating.
stationary plate receiving a glass article awaiting transfer.
crackled—glassware, the surface of which has been intention-
debiteuse—a slotted, floating clay block through which glass
ally cracked by water immersion and partially healed by
issues in the Fourcault process.
reheating before final shaping.
decolorizing—the process of producing a colorless appearance
crescent crack—damage having the appearance of a crescent, in glass.
produced in a glass surface by the frictive translation of a
deflection—displacement of the glass lite perpendicular to the
hard, blunt object across the glass surface. The crescent
plane of the glass surface.
shape is concave toward the direction of translation on the
damaged surface.
deformation point—see dilatometric softening point.
crizzle—an imperfection in the form of a multitude of fine delamination—(1) separation of a glass laminate into constitu-
surface fractures. ent layers.
C162 − 23
(2) the formation of lamellae or flakes in drug products due down-tank—the direction in a glass melting furnace from the
to specific and localized corrosion of glass vials. batch feeding end toward the exit.
delivery—(1) the final act of any glass-forming unit on a dragade—{archaic} see drag ladle.
particular article; consisting of motion to remove the article
drag ladle—{archaic} to produce cullet by ladling glass from
from the mold.
the melt into water.
(2) the process or equipment used for directing charges or
gobs of glass to a forming machine.
draw—see pull.
dense—a term used for optical glass having a high index of
draw bar—a refractory member submerged in molten glass
refraction.
that defines the position of the sheet in a drawing process.
density—the mass of a unit volume of a material at a specified
draw gang—{archaic} people employed to cut and handle
temperature.
glass as it comes from the lehr.
detergent resistance—the degree of resistance to the chemical
drawn glass—glass made by a continuous drawing operation.
action of detergents.
draw line—a mild linear striation parallel to the direction of
devitrification—crystallization of glass.
travel of a glass ribbon.
dice—the more or less cubical fracture typical of fully tem-
dropping—{archaic} forming by heating in a mold without
pered glass.
the use of pressure.
dig—a deep scratch in the glass surface.
drop throat—see submerged throat.
dilatometric softening point—the temperature at which the
dross—a mixture of metal oxide and metal on the surface of a
viscous sag of the glass specimen exactly counteracts the
float bath.
expansion as thermal expansion measurements proceed dur-
dry chop—dried fiber glass strand which has been chopped.
ing heating.
See chopped fiber and wet chop.
direct-fired furnace—a melting furnace having neither recu-
dry gage (drigage), v—to form cullet by running a stream of
perator nor regenerator.
molten glass into a water bath. (See synonymous term frit,
dirt—a small particle of foreign material imbedded in or stuck
v.)
to the surface of the glass.
dummy—a mechanical device, operated by the blower’s feet,
dispersion—the variation of refractive index with wavelength
for wetting, raising, opening and closing the paste mold in
of light. See related term Abbé value.
mouth-blowing glassware.
distortion—alteration of viewed images caused by variations
durability—see chemical durability.
in glass flatness or inhomogeneous portions within the glass.
dwell mark—a fracture surface marking representing the site
distribution—the thicknesses of the walls of a glass article
of a fracture discontinuity caused by a sudden shift in the
over its entire area.
stress distribution or by a fracture stopping for some length
of time; also known as an arrest line.
document glass—{archaic} an ultraviolet absorbing glass
used for protecting documents.
edging—grinding the edge of flat glass to a desired shape or
finish. See also centering.
doghouse—a protrusion in or near the back wall through
which batch is introduced into the melter.
electric boosting—an auxiliary method of adding heat to the
glass in a gas- or oil-fired melter by passing electric current
dolomite—a double carbonate of lime and magnesium having
through the molten glass.
the general formula CaCO · MgCO . See also limestone.
3 3
emissivity—the relative ability of a surface to reflect or emit
dope—slang for mold lubricant.
heat by radiation.
double-cavity mold—see multiple cavity mold.
end-fired furnace—a glass melting furnace with fuel supplied
double-cavity process—see multiple cavity process. from the back wall.
double glazing—insulating glazing that incorporates two lites end-port furnace—synonymous with end-fired furnace.
separated by a gap.
engraving—the process of carving figures, letters, etc., upon
double-gob process—see double-cavity process. glass by abrasive means.
down draw—process of continuously drawing glass down- equilibrium contact angle—the angle observable immedi-
ward from an orifice. ately after a liquid droplet is increased in size.
C162 − 23
etch—to alter the surface of glass with hydrofluoric acid or fine annealing—to attain more uniform structure than ordinar-
other agent, generally for marking or decoration. ily required, maximizing homogeneity of physical properties
by minimizing prior thermally induced variations.
etched—(1) treated by etching.
fine hackle—see mist.
(2) weathered so that surface is roughened.
fining, also refining—the process by which molten glass
fabricator (within the glass industry)—a processor of glass
becomes relatively free of undissolved gases.
and glass-related components or assemblies.
finish—(1) the part of a bottle for holding the cap or closure.
fade—(1) to reduce the color saturation and/or visual promi-
(2) stage in melting process after glass appears free of seeds.
nence.
(3) the quality of a glass surface as influenced by very fine
(2) {archaic} attack of the surface of glass causing an oily or
pits and cracks remaining from a grinding and polishing
whitish surface.
process.
feather—see striation.
finisher—(1) person in charge of a day-tank during the melting
feathers—an imperfection consisting of clusters of fine seed
and fining of the glass.
caused by dirt or foreign material entering the glass at the
(2) the worker who does the final work, such as polishing or
time of casting or shaping.
putting the handle or foot on a piece of ware.
feeder—(1) a mechanical device used to deliver raw batch
fire cracks—small, sometimes microscopic fissure in the edge
materials to the load-end of a glass melting furnace.
of wired or patterned glass.
(2) a mechanical device for regularly producing and deliv-
fire check—a check resulting from localized thermal stress
ering gobs of glass to a forming unit.
during forming.
feeder process—see gob process.
fire cracks—see synonymous term fire check
fiber—attenuated glass generally with a diameter of less than
fire over—idling a melting unit at operating temperature.
a millimeter and a length/diameter ratio of more than 5.
fire-polish—to make glass smooth, rounded, or glossy by
fiber, optical—a fiber with high transmittance, low scattering,
heating the glass surface.
and minimal transverse loss of light.
first side—{archaic} the surface of plate which is ground and
fiberglass, reinforcement—continuously formed fibers added
polished first.
to enhance the overall performance of a matrix. Fiber glasses
used for specific chemical or physical properties, or both, fishbone—a striation that does not reach entirely across the
include:
fracture surface.
A-glass—compositions typically with lower electrical resistivity, strength,
fit—the fit between glaze and body while avoiding crazing or
and durability than E-glass.
shivering induced by differences in thermal expansion.
AR-glass—compositions resistant to corrosion by alkali.
C-glass—compositions resistant to corrosion by most acids.
Typically, the glaze is left in compression.
D-glass—compositions with a low dielectric constant.
E-glass—compositions with electrical properties, strength, and durability
flake-glass—hot glass squeezed thin between two metal rolls
appropriate for most applications.
or blown into a thin film, followed by fracturing into small
E-CR-glass—E-glass compositions modified for improved resistance to
corrosion by most acids. particles.
R-glass—compositions with high tensile strength, resistant to corrosion
by most acids.
flare—a protrusion on the edge of a lite of glass. See fin (1)
S-glass—compositions with high tensile strength, elastic modulus and
and (2).
service temperature.
flashing—applying a thin layer of opaque or colored glass to
figured glass—flat glass having a pattern on one or both
the surface of clear glass or vice versa. See also striking.
surfaces. See patterned glass.
flat glass—a general term covering sheet glass, plate glass,
filament—a single glass fiber of indefinite length.
float glass, fusion drawn glass, and various forms of rolled
fill—the unit charge of batch into a glass melting furnace or glass that are generally planar. See related term bent glass.
pot.
flexural stress—the tensile component of the bending stress
produced on the surface of a glass section opposite to that
filling point—the level at which a glass bottle has the nominal
capacity. experiencing a locally impinging force.
flint optical glass—see optical flint glass.
fin—(1) an imperfection caused by entrance of glass into a
seam between mold parts during forming.
flint glass—(1) a lead-containing glass.
(2) {archaic} the feather edge obtained when cutting flat
(2) term used by container industry for colorless glass.
glass. See flare.
(3) a structural member, the depth of which is typically floater—(1) a floating clay shape to skim foreign materials or
oriented perpendicular to a glazing panel. control their passage in a melter.
C162 − 23
(2) an object, generally a porous silica brick, introduced into fracture mirror radius—a dimension of the fracture mirror as
a melting furnace, which will float on the surface of the measured along the original specimen surface. It is defined
molten glass for tens of minutes to several hours, thus as the distance from the origin to the first detectable mist.
revealing the surface flow.
fracture origin—the single, unique location at which a frac-
floater hole—{archaic} an opening in a melter through which
ture system begins.
floaters are placed.
fracture surface markings—features of the fracture surface
float bath—a pool of molten metal, commonly tin, contained
produced during the fracture event which are useful in
within a refractory receptacle and protected from oxidation
determining the origin and the nature of the local stresses
by an inert atmosphere, upon which molten glass is drawn
that produced the fracture.
into a flat sheet. See float glass.
fracture system—that family of related fracture surfaces lying
float glass—flat glass that has been formed on molten metal,
within an object, having a common cause and origin.
commonly tin. The surface in contact with the tin is known
free-blown—see offhand glass.
as the tin surface or tin side. The top surface is known as the
atmosphere surface or air side.
frictive track—a series of crescent cracks lying along a
common axis, paralleling the direction of frictive contact;
flow hole—{archaic} see throat.
also known as a chatter sleek.
flow process—see gob process.
frit, n—glass in particulate form, generally of controlled size
flux—an ingredient that reduces batch melting temperature.
distribution.
DISCUSSION—For decorations or sealing, it is commonly applied in
flux block—a refractory furnace block used in contact with
combination with an organic vehicle.
glass in melting.
frit, v—(1) the process of pouring molten glass into water or
flux line—see metal line.
between cooled rollers. See shrend and dry gage.
foam—a layer of bubbles on the surface of molten glass.
(2) to decorate or seal with glass in particulate form.
foam glass—a thermally insulating material consisting of a
frosted area—{archaic} see hackle.
high volume fraction of gaseous inclusions distributed
frosted finish—a surface treatment for glass, consisting of
throughout a glass matrix.
etching of one or both surfaces that diffuses transmitted light
foam line—a boundary in a melting furnace beyond which
and reduces glare.
foam no longer appears on the glass surface.
fully tempered glass—a category of tempered flat glass
fold—see lap.
having a high surface or edge compression to meet the
requirements of Specification C1048. See heat-
forehearth—a section of a melting furnace in one of several
forms from which glass is taken for forming. strengthened glass.
forking—a mechanism whereby a propagating fracture
fused silica—vitreous silicon dioxide produced by flame
branches to form two new fractures separated by an acute hydrolysis of silicon tetrachloride (or similar compounds) or
angle.
by thermal consolidation of a silica gel. See related terms
vitreous silica and fused quartz.
forking angle—the angle subtended by two immediately
adjacent fractures which have just branched or forked.
fused quartz—vitreous silicon dioxide produced by melting
silica, generally in the form of granular quartz. See related
forming—the shaping of hot glass.
terms fused silica and vitreous silica.
forming hood—the partially enclosed volume in which indi-
fusion drawn glass—process where molten glass is fed into a
vidual glass fibers and groups of fibers are collected into a
trough called an “isopipe,” filling it until the glass flows
wool pack.
evenly over both sides. It then rejoins, or fuses, at the
forming rolls—rolls used in forming flat glass.
bottom, where it is drawn down to form a continuous sheet
of flat glass.
Fourcault process—{archaic} the method of making sheet
glass by drawing vertically upward from a slotted debiteuse
gable wall—{archaic} the charging end wall of a glass-
block.
melting furnace.
fracture mirror—a smooth portion of a fracture surface
gaffer—head worker, supervisor, or blower of a glass hand
surrounding the fracture origin.
shop.
fracture mirror constant—a mathematical constant, charac-
gall—layer of molten sulfates floating upon glass.
teristic of a given glass composition, which, when divided by
the square root of the fracture mirror radius, will yield the gaseous inclusion—a round or elongated bubble in the glass.
fracture stress. See blister and seed.
C162 − 23
gate—a shut-off device for flow of glass and combustion gases gross sample, n—the total number of sample increments taken
in a forehearth, more commonly a water-cooled device from the lot.
rather than a refractory block.
hackle—a finely structured fracture surface marking giving a
matte or roughened appearance to the surface, having
gather, n—the mass of glass picked up by the hand shop
working on the punty or blowing iron. varying degrees of coarseness. Finely structured hackle is
variously known as fine hackle, frosted area, gray area,
gather, v—to get glass from a pot or day-tank on the pipe or
matte, mist, and stippled area. Coarsely structured hackle is
punty.
also known as striation. In architectural, applies to the cut
edge. In fractography, applies to texture on the facture
girth—in bent glass, the distance around the concave or
surface.
convex surface measured perpendicular to the height, includ-
ing any flats.
hackle marks—fine ridges on the fracture surface of the glass,
parallel to the direction of propagation of the fracture.
glass—an inorganic product of fusion that, when cooled,
transitions to a rigid condition without crystallizing. An
hard glass—(1) a glass of relatively high viscosity at elevated
amorphous solid.
temperatures.
(2) a glass with a high softening point.
glass blowing—the shaping of hot glass by air pressure.
(3) commonly refers to a glass difficult to melt.
glass ceramic—solid material, partly crystalline and partly
head space—the unfilled space in a glass container fitted with
glassy, formed by the controlled crystallization of a glass.
a closure device.
glass container—general term applied to glass bottles and jars.
heat-absorbing glass—glass having the property of absorbing
glass paper—a glass fiber product made by dispersing a substantial percentage of radiant energy in the near infrared
chopped glass fibers in a liquid medium followed by settling of the spectrum, for example, an appreciable amount of solar
and drying to produce a thin sheet. energy.
heat-resisting glass—glass able to withstand a relatively high
glass redox, redox ratio—a measure of the relative oxidation/
reduction state of a glass as indicated typically by any one of thermal shock, because of low expansion coefficient or a
2+ 3+
high mechanical strength, or both.
the ratios: FeO/total iron as Fe O , FeO/Fe O , Fe /Fe , or
2 3 2 3
2+ 2+ 3+
Fe /(Fe + Fe ).
heat-strengthened glass—flat glass that has been thermally
treated to a surface or edge compression to meet the
glass transition temperature—on heating, the temperature at
requirements of Specification C1048. (See fully tempered
which a glass transforms from an elastic to a viscoelastic
material, characterized by the onset of a rapid change in glass.)
thermal expansivity.
heat-treated—term used for both fully tempered glass and
heat-strengthened glass. (See tempered glass).
glazed pot—generally, a new pot coated inside with a thin
layer of glass to protect it from the raw batch.
heel contact—the region on a glass container surface, located
between the bearing surface and the sidewall sections, which
glazing, n—a generic term used to describe an infill material
normally contacts other similarly shaped and upright con-
such as glass, panels, etc.
tainers.
glazing, v—the process of installing an infill material into a
heel tap—an imperfection in which the base or bottom of a
prepared opening in windows, door panels, partitions, etc.
bottle is very thick in one area and very thin in another.
glazing bead—material surrounding the edge of the glass in a
Hertzian cone crack—see percussion cone.
window or door, which holds the glass in place.
Hertzian stress—see contact stress.
glazing channel—a three-sided, U-shaped sash detail into
which a glass product is installed and retained.
high-transmission glass—glass that transmits an exception-
ally high percentage of the visible light, or at the wave length
glory hole—an opening exposing the hot interior of a furnace
of interest.
used to reheat the ware in hand-working.
hinge stress—the tensile component of the bending stress
gob—(1) a portion of hot glass delivered by a feeder.
generated on the same surface of a glass section as, but
(2) a portion of hot glass gathered on a punty or pipe.
displaced from, the site of a locally impinging force.
gob process—a process whereby glass is delivered to a
hot end—those manufacturing operations concerned with hot
forming unit in “gob” form.
glass, that is, melting, forming, annealing.
graduated glassware—glassware that is marked with one or
hot hold—maintaining the temperature of an idled melter
more graduations for volumetric measuring purposes.
below its operating temperature but above the liquidus
gray area—{archaic} see mist. temperature of the glass.
C162 − 23
hot mold—the process of forming glassware in hot uncoated lance—(1) see hackle.
molds. (2) a piece of hardware used for introducing a controlled
atmosphere gas flow into molten glass or into parts of the
hot spot—the zone of highest temperature within a melter.
furnace structure.
hydrophilic, adj—having a strong affinity for water; wettable,
lap—(1) an imperfection; a fold in the surface of a glass article
as defined in Test Method C813.
caused by incorrect flow during forming.
hydrophobic, adj—having little affinity for water; non wet-
(2) a tool used for polishing glass.
table.
laser glass—a glass of special composition that emits ampli-
ice—a glass enamel frit which, when applied to glassware and
fied electromagnetic radiation upon proper electromagnetic
fired, produces a textured surface.
stimulation.
impact bruise—see percussion cone.
lateral crack—a crack produced beneath and generally paral-
leling a glass surface during the unloading phase of mechani-
inclusion—a foreign solid or gas within or bounded by the
cal contact with a hard, sharp object. (See cleavage crack.)
glass matrix.
layer—{archaic} person who has charge of laying the glass in
inside knuckle—the juncture between the inside sidewall and
plaster on the grinding and polishing tables.
the inside bottom surface of a glass article.
insulating glass unit—two or more lites of glass spaced apart
laying yard—{archaic} place where the rough glass is laid on
and hermetically sealed to form a single-glazed unit. (Com- grinding and polishing tables with plaster.
monly called IG units or IGU.)
leaded glass—pieces of glass fixed together at their edges with
interlayer—any material used to bond two lites of glass and/or
soldered strips of lead or other ductile metal.
plastic together to form a laminate. See laminated glass.
lehr—a long, tunnel-shaped oven for controlling temperature
iridescence—see anisotropy.
during continuous passage of glass.
I.S. process—a bottle-making process using removable, indi-
lehr loader—a device for properly placing and spacing glass
vidual forming sections, in which the gob enters the blank or
articles on a continuous lehr belt.
parison mold by gravity.
Libbey-Owens sheet process—{archaic} see Colburn sheet
jamb(s)—the structural member forming a vertical side(s) of a
process.
building opening, or a port in a furnace superstructure,
supporting the crown load.
light-reducing glass—a term applied to flat glass having
reduced light transmittance.
jointing yard—{archaic} place between the grinding and
polishing operations in the continuous manufacture of plate
lime—calcium oxide (CaO), or a mixture of calcium oxide
glass, where the plaster joints are remade, sometimes called
(CaO) and magnesium oxide (MgO).
“middle yard.”
limestone—either calcitic limestone (CaCO ) or dolomitic
knockout—(1) a portion of a piece of pressed ware which has
limestone (CaCO · MgCO ).
3 3
been so designed that it can be knocked out to make a hole.
(2) in glass containers, a protrusion of glass caused by
Lindemann glass—a high X-ray transmittance glass com-
missing metal at a junction of mold parts.
posed of the oxides of lithium, beryllium, and boron. (No
elements with an atomic number above 8.)
knot—an inhomogeneity in the form of a vitreous lump.
line—fine cords or strings, usually on the surface of flat glass.
knurling—in glass containers, a raised pattern of beads,
ridges, crescents, or other shapes, molded on a glass surface
liquidus temperature—the maximum temperature at which
for the purpose of decoration and/or improvement in the
equilibrium exists between the molten glass and its primary
mechanical strength of the glass in
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C162 − 05 (Reapproved 2015) C162 − 23
Standard Terminology of
Glass and Glass Products
This standard is issued under the fixed designation C162; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This terminology defines terms generally used in C14 standards with related additional terms from the glass industry.
1.2 In some cases in which a usage is specific to a certain industry, that is spelled out within the definition. For completeness and
historical purposes, terms that are outdated are listed as being archaic. The reader is cautioned that some companies or industries
may define or use terms differently than the way these terms are defined within this terminology.
1.3 Other sources of glass glossaries are Glass Association of North America’s National Glass Association’s GANA Glazing
2 2 2
Manual, NGA Engineering Standards Manual for Tempered Glass, Laminated Glass Design Guide, and ASTM Committee C-14
standards.
2. Referenced Documents
2.1 ASTM Standards:
C148 Test Methods for Polariscopic Examination of Glass Containers
C336 Test Method for Annealing Point and Strain Point of Glass by Fiber Elongation
C338 Test Method for Softening Point of Glass
C598 Test Method for Annealing Point and Strain Point of Glass by Beam Bending
C813 Test Method for Hydrophobic Contamination on Glass by Contact Angle Measurement
C1048 Specification for Heat-Strengthened and Fully Tempered Flat Glass
C1172 Specification for Laminated Architectural Flat Glass
3. Terminology
Abbé value—the reciprocal dispersive power, a value used in optical design, expressed mathematically as:
Abbe´ value 5 n 2 1 / n 2 n
~ ! ~ !
d F C
where n is the refractive index for the helium line at 587.6 nm and n and n are the refractive indices for the hydrogen
d F C
lines at 486.1486.1 nm and 656.3 nm, respectively. See synonymous term nu-value and related term dispersion.
abraded—describes a test specimen that has at least a portion of the area under test subjected to an operationally defined
This terminology is under the jurisdiction of ASTM Committee C14 on Glass and Glass Products and is the direct responsibility of Subcommittee C14.01 on
Nomenclature and Definitions.
Current edition approved Nov. 1, 2015Oct. 1, 2023. Published November 2015December 2023. Originally approved in 1941. Last previous edition approved in 20102015
as C162 – 05 (2010).(2015). DOI: 10.1520/C0162-05R15.10.1520/C0162-23.
Available from Glass Association of North America (GANA), 2945 SW Wanamaker Drive, Ste A, Topeka, KS 66614-5321. http://www.glasswebsite.com. National Glass
Association (NGA), 344 Maple Ave. West, Unit 272, Vienna, VA 22180. http://www.glass.org.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C162 − 23
procedure for mechanical abrasion. The severity and uniformity of abrasion should be sufficient to ensure origin of failure
substantially in the region of maximum stress.
absorption—a magnitude reduction of electromagnetic energy of neither transmission nor reflection, such as sunlight being
absorbed by tinted glass.
acid polishing—the polishing of a glass surface by acid treatment.
acoustics—the science of sound and sound control.
air bells—bubbles of irregular shape formed generally during the pressing or molding operations in the manufacture of optical
glass.
alabaster glass—a milky-white glass that diffuses light without fiery color.
alcove—a narrow channel to convey molten glass from refiner to forehearth or to the revolving pot where it is gathered by the
Owens machine.
alkali—an industrial term for the oxide of sodium or potassium; less frequently of lithium.
ampoule—a glass container designed to be filled and sealed by fusion of the glass neck.
analyzer—a polarizing element, typically positioned between the specimen being evaluated and the viewer.
anisotropy—a strain pattern inherent in all heat-strengthened and fully tempered glass. This strain pattern may be visible under
certain lighting conditions. It is a characteristic of heat-treated glass and should not be mistaken as discoloration, nonuniform
tint or color, or a defect in the glass. The strain pattern does not affect any physical properties or performance values of the glass.
Also known as iridescence.
anneal—to attain acceptably low stresses, or desired structure, or both, in glass by controlled cooling from a suitable
temperature.
annealed glass—describes glass subjected to the annealing process.
annealing—a controlled cooling process for glass designed to reduce residual stress to a commercially acceptable level and
modify structure.
annealing lehr—an on-line, controlled heating/cooling apparatus located after the glass is formed and before the glass is cooled.
Its purpose is to anneal the glass product.
annealing point (A.P.)—that temperature corresponding either to a specific rate of elongation of a glass fiber when measured
by Test Method C336, or a specific rate of midpoint deflection of a glass beam when measured by Test Method C598. At the
annealing point of glass, internal stresses are substantially relieved in a matter of minutes.
annealing range—the range of glass temperature in which stress in glass can be relieved at a commercially practical rate. For
purposes of comparing glasses, the annealing range is assumed to correspond with the temperature between the annealing point
(A.P.) and the strain point (St.P.). (St.P.)
antimony—an industrial term for an oxide of antimony.
C162 − 23
applied color label (ACL)—a ceramic-glass enamel/ink applied to and fired on a glass surface for the purposes of decoration
and labeling. Also called Applied Ceramic Label.
arch, nn——a part of a melter; glass melting furnace; a crown.
arch, vv——to heat a pot in a pot arch.
architectural glass, n—a general term applied to glass used in the building industry.
arrest mark—See dwell mark.see dwell mark.
arsenic—an industrial term for an oxide of arsenic.
autoclave—a vessel that employs pressure and heat, used to produce a permanent bond between glass and interlayers suitable
for this process, creating a laminated glass product.
aventurine—{archaic} glass containing colored, opaque spangles of nonglassynon-glassy material.
back wall—the wall at the charging end of a melter. glass melting furnace.
baffle—a mold part used to close the delivery or baffle hole in a blank mold.
baffle mark—a mark or seam on a bottle resulting from a mold joint between blank mold and baffle.
baffle wall—a wall used to deflect gases or flames in a melter. glass melting furnace.
See shadow wall.
baghouse—a chamber containing bag filters for the removal of particles from a process exhaust stream.
bait—the tool dipped into molten glass to start any drawing operation.
barrel, glass container—{archaic} See sidewall, glass container.{archaic} see sidewall, glass container.
base—{archaic} the bottom of a bottle.
basic fiber—unprocessed glass fibers directly from the forming equipment.
batch—(1) the recipe of batch ingredients.
(2) the raw materials weighed but unmixed.
(3) the raw materials, properly proportioned and mixed, for delivery to the furnace.
batch charger—a mechanical device for introducing batch to the melter. glass melting furnace.
batch feeder—See batch charger.see batch charger.
batch house—the place where batch materials are received, handled, weighed, and mixed.
C162 − 23
bath—bath—synonymous with float bath.
bead—(1) an enlarged, rounded raised section on a glass article.
(2) a small piece of glass tubing bonded around a wire lead.
(3) in fiber glass, a tear drop-shaped glass mass which forms as a result of the interruption of the fiber forming process below
an orifice.
beam bending viscometer—a device used to determine the viscosity of glass by viscous bending of a loaded beam.
bearer arch—See rider arch.see rider arch.
bearing surface—the outside surface of an item of glassware on which it rests when in its normal upright position.
beltmarks—See chain marks.see chain marks.
bench—See siege.see siege.
bending stress—a stress system that simultaneously imposes a compressive component at one surface, graduating to an imposed
tensile component at the opposite surface of a glass section. continuously and linearly changing stress across the thickness of
a glass body, varying from compression on one surface to tension on the opposite surface.
bent glass—flat previously flat glass that has been shaped while hot into a body having curved surfaces. configured in an
out-of-plane manner by a method such as heating followed by cooling into a new self-sustaining form, or the application of
external sustained load.
beveling—the process of edge finishing flat glass to a bevelbeveled angle.
bicheroux process—{archaic} an intermittent process for making plate glass, in which the glass is cast between rolls, onto
driven conveyer rolls, or a flat moving table.
binder—(1) for a continuous filament process, a constituent of a fiber glass sizing that couples the fiber to the composite matrix.
(2) for insulation, material applied to glass fibers to hold them in a desired arrangement.
bite—the dimension by which the framing system overlaps the edge of the glazing infill.
blank—(1) a preliminary shape from which a finished article is further formed, molded, or cut.
(2) a semi-finished piece of glass for making an optical element, such as a lens or prism. Also known as a pressing.
blank mold—the metal mold that first shapes the glass in the manufacture of hollow ware.
blanket feed—a method for charging batch designed to produce an even distribution of batch across the width of the melter.
glass melting furnace.
blank mold—the metal mold that first shapes the glass in the manufacture of hollow ware.
blending-batch—{archaic} stepwise changes in batch composition to arrive at the final change in finished glass.
C162 − 23
blister—a relatively large gaseous inclusion in glass.
bloach—{archaic} an imperfection resulting from incompletely grinding plate glass, caused by a low place in the plate which
retains part of the original rough surface.
blocking—(1) shaping a gather of glass in a cavity of wood or metal.
(2) archaic, promoting mixing and fining of glass by immersion of a wooden block or other object to create bubbles.
(3) reprocessing to remove surface imperfections.
(4) archaic, mounting of glass for grinding and polishing.
(5 ) archaic, idling a furnace at reduced temperatures.
See hot hold.
block mold—a one-piece mold.
block reek, rake—{archaic} a scratch imperfection caused by cullet lodged in the felt in the polishing operation.
bloom—(1) a visible surface film resulting from attack by the atmosphere or from the deposition of particulate or vapor
condensates. (See also smoked.)
(2) a blemish in float glass appearing on the bottom (tin contact) surface after reheating as a result of the presence of tin diffused
into the surface.
blow-and-blow process—the process of forming hollow ware in which both the preliminary and final shapes are formed by air
pressure.
blower—one who forms glass by blowing. (See also gaffer.)
blow head—part of a forming machine serving to introduce air under pressure to blow any hollow glass article.
blow-over—the thin-walled bubble formed above a blow mold in hand-shop operation to facilitate bursting-off.
blowpipe—the pipe used by a glassmaker for gathering and blowing by mouth.
blowing iron—See blowpipe.see blowpipe.
blown glass—glassware shaped by air pressure, as by compressed air or by mouth blowing.
blow mold—the metal mold in which a blown glass article is finally shaped.
body—the attribute of molten glass, associated with viscosity and homogeneity, which is conducive to workability.
boil—(1) {archaic} an imperfection; a gaseous inclusion larger in size than a seed.
(2) turbulence caused by gases escaping from the melting batch.
boil (bubble)—in laminated glass, a gas pocket in the interlayer material or between the glass and the interlayer.
boost melting—See electric boosting.see electric boosting.
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boot—a suspended enclosure in the nose of a melter glass melting furnace protecting a portion of the surface and serving as
a gathering opening.
borax glass—vitreous anhydrous sodium tetraborate (Na B O ).
2 4 7
borosilicate glass—a silicate glass with B O content above 4 weight percent, characterized by a moderate to low thermal
2 3
expansion, long in viscosity versus temperature, and low in density.
bow—a condition in which a lite of flat glass departs from a true plane.
bowl—See spout.see spout.
breast wall—(1) the entire side wall of a melter glass melting furnace between the flux block and the crown, but not including
the ends.
(2) refractory wall between pillars of a pot furnace and in front of or surrounding the front of a pot.
breezing—{archaic} buckwheat anthracite coal or coarse sand spread on the siege before setting of pots.
bridge—the structure formed by the end walls of the adjacent melter and refiner compartments of a melting furnace and the
covers spanning the gap between the end walls.
bridge cover—See bridge wall cover.see bridge wall cover.
bridge wall cover—refractory blocks spanning the space between the bridge walls.
bridgewall—that part of a glass melting furnace forming a bridge or separation between melter and refiner.
bruise—bruise—synonymous with percussion cone.
bulb edge—the heavy rounded edge or bead of flat glass. glass, for example, the extreme lateral edge of the ribbon of flat glass
as drawn.
bull’s eye—(1) a tempered solid cylindrical sight glass.
(2) the glass left by the punty in the center of a flat disk of glass made by the hand blown crown process.
(3) in flat glass, an optical distortion that arises from a polishing depression or a solid inclusion trapped between layers of
laminated glass.
bump check—See percussion cone.see percussion cone.
burner block—a refractory block with one or more orifices through which fuel is admitted to a furnace.
burn-off—the process of severing an unwanted portion of a glass article by fusing the glass.
burnt lime—calcined limestone (CaO · MgO, dolomitic), or CaO (calcitic), or a mixture of these.
bursting-off—the breaking of the blowover.
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bushing—(1) a liner in the feeder orifice for molten glass.
(2) a precious metal or refractory/metal structure with single or multiple hole(s) through which glass flows and is attenuated into
fiber(s).
butterfly bruise—See percussion cone.see percussion cone.
cabal glass—a glass consisting primarily of the oxides of calcium, boron, and aluminum.
campaign—the working life of a melting furnace between major cold repairs.
canal—that part of a melting furnace leading from the fining area to the forming area. See channel and forehearth.
cane—solid glass rods.
cap, n—(1) another name for crown.
(2) a type of bottle closure.
cap, v—{archaic} to cut off the ends of a glass cylinder.
carnival glass—glass having an iridescent coloration obtained by firing metallic salts applied onto a colored glass body. See
lusters.
carry-in—manual lehr loading.
cased glass—glassware whose surface layer has a different composition from that of the main glass body.
casehardened—a term sometimes used for tempered glass. (See tempered glass.)
cast glass—glass cooled in the pot in which it was melted.
casting—a process of shaping glass by pouring molten glass into molds, onto tables, or between rollers. molds.
cat eye—an imperfection; an elongated bubble containing a piece of foreign matter.
cat scratch—an imperfection; surface irregularities on glassware streak(s) on the surface of glass containers which has a slightly
different chemical composition than the base glass typically resulting from refractory dissolution by molten glass and resembling
the marks of a cat’s claws. Also referred to as “surface cord”, “mare’s tail”, or “feeder streak”.
centering—an operation on lens elements wherein the element is optically aligned with the axis of rotation and the edges ground
concentric with the optical axis.
ceramic glass decorations—ceramic glass enamels applied to and fused to glass at the enamel melt temperatures to produce
a decoration.
ceramic glass enamel (also ceramic enamel or glass enamel)—a functional and/or a decorative, usually colored, vitreous
inorganic coating for bonding to glass at temperatures above 425°C (800°F). melt temperatures typically composed of glass frit,
inorganic pigments and an organic medium.
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chain marks—marks made on the bottoms of glass articles as they ride through a lehr on a chain belt slightly overheated. belt.
channel—(1) in container glass, that part of a forehearth which carries the glass from the melter to the flow spout and in which
temperature adjustments are made.
(2) in fiber glass, the structure to deliver glass from the melter to the refiner or forehearth.
charge, ncharge,—n—Seesee batch ((3).3).
charge, vv——to add batch to a melter. glass melting furnace.
chatter sleek—{archaic} See frictive track.{archaic} see frictive track.
check—an imperfection; a surface crack in a glass article.
checkers—(1) an open structure of firebrick serving as a heat exchanger.
(2) slang for regenerators of this type.
(3) slang for refractory brick used in such a construction.
chemical durability—the lasting quality (both physical and chemical) of a glass surface. It is frequently evaluated, after
prolonged weathering or storing, in terms of chemical and physical changes in the glass surface, or in terms of changes in the
contents of a vessel.
chemical vapor deposition (CVD)—a process in which a gaseous chemical mixture is brought in contact with the hot glass
substrate and a pyrolytic reaction occurs at the surface of the substrate leading to the deposition of a coating which bonds to
the glass.
chemically strengthen—conducting ion exchange of constituent alkali ions in a glass product by immersing it in a bath of
molten salt containing larger alkali ions. Penetration of the larger ions into smaller host sites produces a layer of compression
on the surface which strengthens the glass.
chemically strengthened—strengthened glass—glass that has been ion-exchanged strengthened by ion-exchange to produce
a compressive stress layer at the treated surface.
chill mark—a wrinkled surface condition on glassware resulting from uneven cooling in the forming process.
chip—an imperfection due to breakage of a small fragment out of an otherwise regular surface.
chipped glass—a decorative glass article with chipped surface produced intentionally.
chipping—the process of removing thin extra glass prior to grinding.
choke—an imperfection consisting of an insufficient opening in the finish and neck of a container.
chopped fiber—fiber glass strand which has been chopped to specified lengths.
chunk glass—{archaic} optical glass obtained in breaking open a pot of transfer glass.
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cleavage crack—damage produced by the translation of a hard, sharp object across a glass surface. This fracture system
typically includes a plastically deformed groove on the damaged surface, together with median and lateral cracks emanating
from this groove.
Colburn sheet process—{archaic} manufacture of sheet glass by bending the vertically drawn sheet over a roll which
establishes the definition of draw.
cold top melter—an all electric melting furnace in which a thermally insulating layer of batch is maintained on top of the molten
glass.
compact—to treat glass in a manner, such as by heat treatment, to approach maximum density.
contact stress—the tensile stress component imposed at a glass surface immediately surrounding the contact area between the
glass surface and an object generating a locally applied force.
continuous filament—a single glass fiber of sufficiently small diameter to be flexible enough for textile uses and of great or
indefinite length.
continuous furnace—furnace—synonymous with melter.glass melting furnace.
cooling-down period—{archaic} (1) the time elapsing after a covered pot is opened before the glass is cool enough to work.
(2) period between fining stage and the removal of the glass from the furnace.
(2) period between fining stage and the removal of the glass from the furnace.
cooling rate—See setting rate.see setting rate.
cord—a generally an attenuated glassy inclusion with possessing optical and other properties differing from those of the
surrounding glass.
corrugated glass—glass rolled to produce a corrugated contour.
crack-off—the process of severing a glass article by breaking, as by scratching and then heating.
crackled—glassware, the surface of which has been intentionally cracked by water immersion and partially healed by reheating
before final shaping.
crack-off—the process of severing a glass article by breaking, as by scratching and then heating.
crescent crack—damage having the appearance of a crescent, produced in a glass surface by the frictive translation of a hard,
blunt object across the glass surface. The crescent shape is concave toward the direction of translation on the damaged surface.
crizzle—an imperfection in the form of a multitude of fine surface fractures.
Crookes glass—a glass having low transmission for ultraviolet light, and containing cerium and other rare earths.
cross-fired furnace—See side-fired furnace.see side-fired furnace.
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crown—the top or roof of a melter. glass melting furnace.
crown optical glass—See optical crown glass.see optical crown glass.
crown process—{archaic} a method of making flat glass by blowing a large bulb, opening it, and then spinning it flat.
crush—on flat glass sheets, a lightly pitted condition with a dull gray appearance.
crystal glass—(1) colorless, highly transparent glass which is frequently used for art or tableware.
(2) colorless, highly transparent glass historically containing lead oxide.
cullet—glass product or portions of product usually suitable for addition to raw batch.a collection of broken glass that may be
processed and sorted
(a)—foreign cullet—cullet from an outside source. based on color and/or chemistry. It may be reintroduced as an essential
ingredient
(b)—domestic cullet (factory cullet)—cullet from within the plant. in the raw
(c)—a portion of a glass article that will later be cut off and discarded or remelted. batch in glass making to facilitate melting.
cullet cut—synonymous with block reek.
cut glass—glassware decorated by grinding figures or patterns on its surface by abrasive means, followed by polishing.
cut-off scar—a mark on the base of a glass bottle caused by the cutting of the gob in the Owens process.
cut sizes—size—flat glass sheets cut to specific dimensions. ordered cut to its final intended size.
cutter—(1) a workman engaged in grinding designs on glass.
(2) one who cuts flat glass.
(3) the tool used in cutting glass.
cutting—(1) scoring flat glass with a diamond or a steel wheel, diamond, steel wheel, or other hard alloy wheel and breaking
it along the scratch.score.
(2) producing cut glass. Other methods of cutting glass include water jet and laser.
cycle—the firing period in a regenerative furnace.
cylinder process—{archaic} manufacture of window glass wherein molten glass is blown and drawn into the form of a cylinder,
which is subsequently split longitudinally, reheated in a flattening kiln, and flattened.
Danner process—a mechanical process for continuously drawing glass cane or tubing from a rotating mandrel.
day tank—a periodic melting unit, which supplies glass for small volume applications.
DISCUSSION—
It is usually emptied each day.
dead anneal—jargon for a state of negligible residual stress.
dead plate—in automatic production of molded glass, a stationary plate receiving a glass article awaiting transfer.
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debiteuse—a slotted, floating clay block through which glass issues in the Fourcault process.
decolorizing—the process of producing a colorless appearance in glass.
deflection—displacement of the glass lite perpendicular to the plane of the glass surface.
deformation point—point—Seesee dilatometric softening point.
delamination—(1) separation of a glass laminate into constituent layers.
(2) the formation of lamellae or flakes in drug products due to specific and localized corrosion of glass vials.
delivery—(1) the final act of any glass-forming unit on a particular article; consisting of motion to remove the article from the
mold.
(2) the process or equipment used for directing charges or gobs of glass to a forming machine.
dense—a term used for optical glass having a high index of refraction.
density—the mass of a unit volume of a material at a specified temperature.
detergent resistance—the degree of resistance to the chemical action of detergents.
devitrification—crystallization of glass.
dice—the more or less cubical fracture typical of fully tempered glass.
digs—dig—deep, short scratches. a deep scratch in the glass surface.
dilatometric softening point—the temperature at which the viscous sag of the glass specimen exactly counteracts the expansion
as thermal expansion measurements proceed during heating.
DISCUSSION—
10 11
This phenomenon generally occurs in the viscosity range of 10 to 10 Pa-s.
direct-fired furnace—a melting furnace having neither recuperator nor regenerator.
dirt—a small particle of foreign material imbedded in or stuck to the surface of flat glass sheets. the glass.
dispersion—the variation of refractive index with wavelength of light. See related term Abbé value.
distortion—alteration of viewed images caused by variations in glass flatness or inhomogeneous portions within the glass.
distribution—the thicknesses of the walls of a glass article over its entire area.
document glass—{archaic} an ultraviolet absorbing glass used for protecting documents.
doghouse—a protrusion in or near the back wall through which batch is introduced into the melter.
dolomite—a double carbonate of lime and magnesium having the general formula CaCO · MgCO . See also limestone.
3 3
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dope—slang for mold lubricant.
double-cavity mold—mold—see multiple cavity mold.
double-cavity process—process—see multiple cavity process.
double glazing—insulatedinsulating glazing that incorporates two paneslites separated by an air a gap.
double glazing unit—two panes of glass separated by a permanently sealed cavity.
double-gob process—See double-cavity process.see double-cavity process.
down draw—process of continuously drawing glass downward from an orifice.
down-tank—the direction in a melter glass melting furnace from the batch feeding end toward the exit.
dragade—{archaic} see drag ladle.
drag ladle—{archaic} to produce cullet by ladling glass from the melt into water.
draw—See pull.see pull.
draw bar—a refractory member submerged in molten glass that defines the position of the sheet in a drawing process.
draw gang—{archaic} people employed to cut and handle glass as it comes from the lehr.
drawn glass—glass made by a continuous drawing operation.
draw line—a mild linear striation parallel to the direction of travel of a glass ribbon.
dropping—{archaic} forming by heating in a mold without the use of pressure.
drop throat—See submerged throat.see submerged throat.
dross—a mixture of metal oxide and metal on the surface of a float bath.
dry chop—dried fiber glass strand which has been chopped. See chopped fiber and wet chop.
dry gage (drigage)(drigage), v.—v—to form cullet by running a stream of molten glass into a water bath. (See
synonomoussynonymous term frit, v.)
dummy—a mechanical device, operated by the blower’s feet, for wetting, raising, opening and closing the paste mold in
mouth-blowing glassware.
durability—See chemical durability.see chemical durability.
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dwell mark—a fracture surface marking representing the site of a fracture discontinuity caused by a sudden shift in the stress
distribution or by a fracture stopping for some length of time; also known as an arrest line.
edging—grinding the edge of flat glass to a desired shape or size.finish. See also centering.
electric boosting—an auxiliary method of adding heat to the glass in a gas- or oil-fired melter by passing electric current through
the molten glass.
emissivity—the relative ability of a surface to reflect or emit heat by radiation.
end-fired furnace—a melter glass melting furnace with fuel supplied from the back wall.
end-port furnace—furnace—synonymous with end-fired furnace.
engraving—the process of carving figures, letters, etc., upon glass by abrasive means.
equilibrium contact angle—the angle observable immediately after a liquid droplet is increased in size.
etch—to attackalter the surface of glass with hydrofluoric acid or other agent, generally for marking or decoration.
etched—(1) treated by etching.
(2) weathered so that surface is roughened.
eye—fabricator (within the glass industry)—the opening in the bottom of a pot furnace through which the flame enters. a
processor of glass and glass-related components or assemblies.
fade—(1) to reduce the color saturation and/or visual prominence.
(2) {archaic} attack of the surface of glass causing an oily or whitish surface.
feather—feather—Seesee striation .striation.
feathers—an imperfection consisting of clusters of fine seed caused by dirt or foreign material entering the glass at the time of
casting or shaping.
feeder—(1) a mechanical device used to deliver raw batch materials to the load-end of a glass melting furnace.
(2) a mechanical device for regularly producing and delivering gobs of glass to a forming unit.
feeder process—See gob process.see gob process.
fiber—attenuated glass generally with a diameter of less than a millimetremillimeter and a length/diameter ratio of more than
5.
fiber, optical—a fiber with high transmittance, low scattering, and minimal transverse loss of light.
fiberglass, reinforcement—continuously formed fibers added to enhance the overall performance of a matrix. Fiber glasses
used for specific chemical or physical properties, or both, include:
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A-glass—compositions typically with lower electrical resistivity, strength,
and durability than E-glass.
AR-glass—compositions resistant to corrosion by alkali.
C-glass—compositions resistant to corrosion by most acids.
D-glass—compositions with a low dielectric constant.
E-glass—compositions with electrical properties, strength, and durability
appropriate for most applications.
E-CR-glass—E-glass compositions modified for improved resistance to
corrosion by most acids.
R-glass—compositions with high tensile strength, resistant to corrosion
by most acids.
S-glass—compositions with high tensile strength, elastic modulus and
service temperature.
A-glass—compositions typically with lower electrical resistivity, strength, and durability than E-glass.
AR-glass—compositions resistant to corrosion by alkali.
C-glass —compositions resistant to corrosion by most acids.
D-glass—compositions with a low dielectric constant.
E-glass—compositions with electrical properties, strength, and durability appropriate for most applications.
E-CR-glass—E-glass compositions modified for improved resistance to corrosion by most acids.
R-glass—compositions with high tensile strength, resistant to corrosion by most acids.
S-glass—compositions with high tensile strength, elastic modulus and service temperature.
figured glass—flat glass having a pattern on one or both surfaces. See patterned glass.
filament—a single glass fiber of indefinite length.
fill—the unit charge of batch into a melter glass melting furnace or pot.
filling point—the level at which a glass bottle has the nominal capacity.
fin—(1) an imperfection caused by entrance of glass into a seam between mold parts during forming.
(2) {archaic} the feather edge obtained when cutting flat glass. See flare.
(3) a structural member, the depth of which is typically oriented perpendicular to a glazing panel.
fine annealing—to attain more uniform structure than ordinarily required, maximizing homogeneity of physical properties by
minimizing prior thermally induced variations.
fine hackle—See mist.see mist.
fining, also refining—the process by which molten glass becomes relatively free of undissolved gases.
finish—(1) the part of a bottle for holding the cap or closure.
(2) stage in melting process after glass appears free of seeds.
(3) the quality of a glass surface as influenced by very fine pits and cracks remaining from a grinding and polishing process.
finisher—(1) person in charge of a day-tank during the melting and fining of the glass.
(2) the workmanworker who does the final work, such as polishing or putting the handle or foot on a piece of ware.
fire cracks—small, sometimes microscopic fissure in the edge of wired or patterned glass.
fire check—a check resulting from localized thermal stress during forming.
fire cracks—cracks—see synonomoussynonymous term fire check.check
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fire over—idling a melting unit at operating temperature.
fire-polish—to make glass smooth, rounded, or glossy by heating the glass surface.
first side—{archaic} the surface of plate which is ground and polished first.
fishbone—a striation that does not reach entirely across the fracture surface.
fit—the fit between glaze and body while avoiding crazing or shivering induced by differences in thermal expansion. Typically,
the glaze is left in compression.
flake-glass—hot glass squeezed thin between two metal rolls or blown into a thin film, followed by fracturing into small
particles.
flare—a protrusion on the edge of a lite of glass. See fin (1) and (2).
flashing—applying a thin layer of opaque or colored glass to the surface of clear glass or vice versa. See also striking.
flat glass—a general term covering sheet glass, plate glass, float glass, fusion drawn glass, and various forms of rolled glass.
glass that are generally planar. See related term bent glass.
flexureflexural stress—the tensile component of the bending stress produced on the surface of a glass section opposite to that
experiencing a locally impinging force.
flint optical glass—See optical flint glass.see optical flint glass.
flint glass—(1) a lead-containing glass.
(2) term used by container industry for colorless glass.
floater—(1) a floating clay shape to skim foreign materials or control their passage in a melter.
(2) an object, generally a porous silica brick, introduced into a melting furnace, which will float on the surface of the molten
glass for tens of minutes to several hours, thus revealing the surface flow.
floater hole—{archaic} an opening in a melter through which floaters are placed.
float bath—a pool of molten metal, commonly tin, contained within a refractory receptacle and protected from oxidation by an
inert atmosphere, upon which molten glass is drawn into a flat sheet. See float glass.
float glass—flat glass that has been formed on molten metal, commonly tin. The surface in contact with the tin is known as the
tin surface or tin side. The top surface is known as the atmosphere surface or air side.
flow hole—{archaic} See throat.{archaic} see throat.
flow process—See gob process.see gob process.
flux—an ingredient that reduces batch melting temperature.
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flux block—a refractory furnace block used in contact with glass in melting.
flux line—See metal line.see metal line.
foam—a layer of bubbles on the surface of molten glass.
foam glass—a thermally insulating material consisting of a high volume fraction of gaseous inclusions distributed throughout
a glass matrix.
foam line—a boundary in a melting furnace beyond which foam no longer appears on the glass surface.
fold—See lap.see lap.
forehearth—a section of a melting furnace in one of several forms from which glass is taken for forming.
forking—a mechanism whereby a propagating fracture branches to form two new fractures separated by an acute angle.
forking angle—the angle subtended by two immediately adjacent fractures which have just branched or forked.
forming—the shaping of hot glass.
forming hood—the partially enclosed volume in which individual glass fibers and groups of fibers are collected into a wool
pack.
forming rolls—rolls used in forming flat glass.
Fourcault process—{archaic} the method of making sheet glass by drawing vertically upward from a slotted debiteuse block.
fracture mirror—a smooth portion of a fracture surface surrounding the fracture origin.
fracture mirror constant—a mathematical constant, characteristic of a given glass composition, which, when divided by the
square root of the fracture mirror radius, will yield the fracture stress.
fracture mirror radius—a dimension of the fracture mirror as measured along the original specimen surface. It is defined as
the distance from the origin to the first detectable mist.
fracture origin—the single, unique location at which a fracture system begins.
fracture surface markings—fracture surface features that may be used to determine the fracture origin location features of the
fracture surface produced during the fracture event which are useful in determining the origin and the nature of the stress local
stresses that produced the fracture.
fracture system—that family of related fracture surfaces lying within an object, having a common cause and origin.
free-blown—See offhand glass.see offhand glass.
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frictive track—a series of crescent cracks lying along a common axis, paralleling the direction of frictive contact; also known
as a chatter sleek.
frit, n—glass in particulate form, generally of controlled size distribution.
DISCUSSION—
For decorations or sealing, it is commonly applied in combination with an organic vehicle.
frit, v—(1) the process of pouring molten glass into water or between cooled rollers. See shrend,shrend and dry gage.
(2) to decorate or seal with glass in particulate form.
frosted—surface treated to scatter light or to simulate frost.
frosted area—{archaic} See hackle.{archaic} see hackle.
frosted finish—a surface treatment for glass, consisting of etching of one or both surfaces that diffuses transmitted light and
reduces glare.
fully tempered glass—flat glass that has been tempered toa category of tempered flat glass having a high surface or edge
compression to meet the requirements of Specification C1048. See heat-strengthened glass.
fused silica—vitreous silicon dioxide produced by flame hydrolysis of silicon tetrachloride (or similar compounds) or by
thermal consolidation of a silica gel. See related terms vitreous silica and fused quartz.
fused quartz—vitreous silicon dioxide produced by melting silica, generally in the form of granular quartz. See related terms
fused silica and vitreous silica.
fusion drawn glass—process where molten glass is fed into a trough called an “isopipe,” filling it until the glass flows evenly
over both sides. It then rejoins, or fuses, at the bottom, where it is drawn down to form a continuous sheet of flat glass.
gable wall—{archaic} the charging end wall of a glass-melting furnace.
gaffer—head workman, foreman,worker, supervisor, or blower of a glass hand shop.
gall—layer of molten sulfates floating upon glass.
gaseous inclusion—a round or elongated bubble in the glass. See blister and seed.
gate—a shut-off device for flow of glass and combustion gases in a forehearth, more commonly a water-cooled memberdevice
rather than a refractory body.block.
gather, nn——the mass of glass picked up by the hand shop working on the punty or blowing iron.
gather, vv——to get glass from a pot or day-tank on the pipe or punty.
girth—in bent glass, the distance around the concave or convex surface measured perpendicular to the height, including any
flats.
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glass—an inorganic product of fusion that has cooled that, when cooled, transitions to a rigid condition without crystallizing.
An amorphous solid.
DISCUSSION—
Glass is typically hard and brittle, and has a conchoidal fracture.
A glass may be colorless or colored. It is usually transparent, but may be made translucent or opaque.
When a specific kind of glass is indicated, such descriptive terms as flint glass, barium glass, and window glass should be used following the basic
definition, but the qualifying term is to be used as understood by trade custom.
Objects made of glass are loosely and popularly referred to as glass, such as glass for a tumbler, a barometer, a window, a magnifier, or a mirror.
glass blowing—the shaping of hot glass by air pressure.
glass ceramic—solid material, partly crystalline and partly glassy, formed by the controlled crystallization of a glass.
glass container—general term applied to glass bottles and jars.
glass paper—a glass fiber product made by dispersing chopped glass fibers in a liquid medium followed by settling and drying
to produce a thin sheet.
glass redox, redox ratio—a measure of the relative oxidation/reduction state of a glass as indicated typically by any one of the
2+ 3+ 2+ 2+ 3+
ratios: FeO/total iron as Fe O , FeO/Fe O , Fe /Fe , or Fe /(Fe + Fe ).
2 3 2 3
glass transition temperature—on heating, the temperature at which a glass transforms from an elastic to a viscoelastic material,
characterized by the onset of a rapid change in thermal expansivity.
glazed pot—generally, a new pot coated inside with a thin layer of glass to protect it from the raw batch.
glazing, n—a generic term used to describe an infill material such as glass, panels, etc.
glazing, v—the process of installing an infill material into a prepared opening in windows, door panels, partitions, etc.
glazing bead—material surrounding the edge of the glass in a window or door, which holds the glass in place.
glazing channel—a three-sided, U-shaped sash detail into which a glass product is installed and retained.
glory hole—an opening exposing the hot interior of a furnace used to reheat the ware in hand-working.
gob—(1) a portion of hot glass delivered by a feeder.
(2) a portion of hot glass gathered on a punty or pipe.
gob process—a process whereby glass is delivered to a forming unit in “gob” form.
graduated glassware—glassware that is marked with one or more graduations for volumetric measuring purposes.
gray area—{archaic} See mist.{archaic} see mist.
gross sample, n—the total number of sample increments taken from the lot.
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hackle—a finely structured fracture surface marking giving a matte or roughened appearance to the surface, having varying
degrees of coarseness. Finely structured hackle is variously known as fine hackle, frosted area, gray area, matte, mist, and
stippled area. Coarsely structured hackle is also known as striation. In architectural, applies to the cut edge. In fractography,
applies to texture on the facture surface.
hackle marks—fine ridges on the fracture surface of the glass, parallel to the direction of propagation of the fracture.
hard glass—(1) a glass of relatively high viscosity at elevated temperatures.
(2) a glass with a high softening point.
(3) commonly refers to a glass difficult to melt.
head space—the unfilled space in a glass container fitted with a closure device.
heat-absorbing glass—glass having the property of absorbing a substantial percentage of radiant energy in the near infrared of
the spectrum. spectrum, for example, an appreciable amount of solar energy.
heat-resisting glass—
...