ASTM C242-21

Standard Terminology of Ceramic Whitewares and Related Products

SCOPE
1.1 This terminology pertains to the terminology used in ceramic whitewares and related products.  
1.2 Words adequately defined in standard dictionaries are not included. Included are words that are peculiar to this industry. Double words, hyphenated words, or phrases are listed alphabetically under the first word; additional important words are cross-referenced.  
1.3 For definitions of terms relating to surface imperfections on ceramics, refer to Terminology F109.  
1.4 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.

General Information

• Status: Published
• Publication Date: 30-Sep-2021
• ICS: 01.040.81 - Glass and ceramics industries (Vocabularies)
• ICS: 81.060.20 - Ceramic products
• ICS: 97.040.60 - Cookware, cutlery and flatware
• Technical Committee: C21 - Ceramic Whitewares and Related Products
• Drafting Committee: C21.01 - Editorial and Terminology

Relations

• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM F109-12 - Standard Terminology Relating to Surface Imperfections on Ceramics
• Effective Date: 15-Jan-2012
• Refers: ASTM F109-11 - Standard Terminology Relating to Surface Imperfections on Ceramics
• Effective Date: 15-Mar-2011
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM F109-04(2009) - Standard Terminology Relating to Surface Imperfections on Ceramics
• Effective Date: 01-Jan-2009
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06 - Standard Terminology Relating to Water
• Effective Date: 15-Feb-2006
• Refers: ASTM F109-04 - Standard Terminology Relating to Surface Imperfections on Ceramics
• Effective Date: 01-May-2004
• Refers: ASTM D1129-04 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2004
• Refers: ASTM D1129-04e1 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2004
• Refers: ASTM D1129-03a - Standard Terminology Relating to Water
• Effective Date: 10-Aug-2003
• Refers: ASTM D1129-03 - Standard Terminology Relating to Water
• Effective Date: 10-Mar-2003
• Refers: ASTM D1129-02a - Standard Terminology Relating to Water
• Effective Date: 10-Jul-2002
• Refers: ASTM D1129-01 - Standard Terminology Relating to Water
• Effective Date: 10-Jul-2002

Overview

ASTM C242-21: Standard Terminology of Ceramic Whitewares and Related Products is an international standard published by ASTM International. This terminology standard provides industry-specific definitions for words and phrases commonly used in the field of ceramic whitewares and related products. Its purpose is to ensure clear communication and mutual understanding among professionals engaged in manufacturing, quality control, testing, and trading of ceramic products. The vocabulary covered in ASTM C242-21 is unique to ceramic whitewares and is not duplicated in general dictionaries. For terminology related to surface imperfections on ceramics, users are referred to ASTM F109.

Key Topics

ASTM C242-21 addresses terminology essential to the ceramic whitewares sector, including:

• Industry-Specific Definitions: Terms and phrases that are unique or have specialized meanings in ceramic whitewares.
• Alphabetical Organization: Double words, hyphenated terms, and phrases are listed alphabetically, with significant terms cross-referenced for ease of use.
• Physical and Chemical Properties: Definitions related to density, absorption, adsorption, porosity, particle size, and surface coatings.
• Manufacturing Processes: Terminology for common ceramic processes like ball milling, blunging, firing (bisque, glost, single), casting methods (drain, solid), and hot pressing.
• Product Types: Precise definitions for products including porcelain, bone china, earthenware, tile (mosaic, faience, pavers), and technical ceramics such as alumina or steatite whitewares.
• Defect and Quality Terms: Language surrounding flaws and manufacturing variance, such as blistering, bloating, crazing, pinholes, dunning, and orangepeel.
• Test Methods and Measurements: Terms describing testing methodologies, such as coefficient of friction, modulus of rupture, mean coefficient of thermal expansion, and moisture expansion.

Applications

ASTM C242-21 is widely used in:

• Manufacturing: Assisting ceramic manufacturers in defining material requirements, product characteristics, process steps, and quality benchmarks.
• Quality Assurance: Establishing a common vocabulary for inspection staff and laboratories when describing and classifying product characteristics or defects.
• Product Specification and Procurement: Reaffirming mutual understanding in purchase contracts and technical datasheets for ceramic whitewares, tiles, and components.
• Testing and Research: Providing terminology for laboratories and research institutions conducting materials testing or developing new ceramic formulations.
• Education and Training: Serving as a reference for industry newcomers, students, and professionals updating their knowledge of current industry language and best practices.

Related Standards

ASTM C242-21 references and is compatible with several related standards, including:

• ASTM F109: Terminology Relating to Surface Imperfections on Ceramics - for detailed defect definitions.
• ASTM D1129: Terminology Relating to Water - for terms associated with water in testing and processing.
• BS 2955: British Standard Glossary of Terms Relating to Powders - supporting terminology for powder technology.
• Other ASTM practices: Especially those withdrawn, such as E180 and F465, which historically provided guidelines on test precision and accuracy.

Practical Value

Utilizing ASTM C242-21 helps professionals and organizations:

• Achieve Consistency: Standardized terminology reduces miscommunication across international markets and supply chains.
• Enhance Product Quality: Accurate descriptions help pinpoint issues during production and support targeted improvements.
• Meet Compliance Requirements: Adhering to industry-standard language facilitates conformity with regulatory and trade standards.
• Support Technical Documentation: Writers of manuals, data sheets, and standards benefit from a consistent vocabulary.

For comprehensive and up-to-date terminology in ceramics, ASTM C242-21 stands as the authoritative reference, supporting clarity and uniformity across the ceramic whitewares industry.

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: C242 − 21
Standard Terminology of
Ceramic Whitewares and Related Products
This standard is issued under the fixed designation C242; 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 3. Terminology
1.1 This terminology pertains to the terminology used in
absolute or true density—see absolute or true density under
ceramic whitewares and related products.
density.
1.2 Words adequately defined in standard dictionaries are absorbance—the logarithm of that fraction of an incident light
beam that is dissipated in the sample, being neither trans-
not included. Included are words that are peculiar to this
industry. Double words, hyphenated words, or phrases are mitted nor reflected.
listed alphabetically under the first word; additional important
absorbed moisture—water held mechanically in the material
words are cross-referenced.
and having physical properties not substantially different
1.3 For definitions of terms relating to surface imperfec-
from ordinary water at the same temperature and pressure.
tions on ceramics, refer to Terminology F109.
absorption—(1) the relationship of the weight of the water
1.4 This international standard was developed in accor-
absorbed by a ceramic specimen, subjected to prescribed
dance with internationally recognized principles on standard-
immersion procedure, to the weight of the dry specimen; (2)
ization established in the Decision on Principles for the
the capacity of a substance to take up a substance, usually a
Development of International Standards, Guides and Recom-
liquid or gas, with the formation of an apparently homoge-
mendations issued by the World Trade Organization Technical
neous mixture.
Barriers to Trade (TBT) Committee.
adsorption—the capacity of a substance to accept and retain
2. Referenced Documents
on its surface a layer of another substance, usually a gas or
a liquid.
2.1 ASTM Standards:
D1129 Terminology Relating to Water
agglomerate—a jumbled mass or collection of two or more
E180 Practice for Determining the Precision of ASTM
particles or aggregates, or a combination thereof, held
Methods for Analysis and Testing of Industrial and Spe-
together by relatively weak cohesive forces caused by weak
cialty Chemicals (Withdrawn 2009)
chemical bonding or an electrostatic surface charge gener-
F109 Terminology Relating to Surface Imperfections on
ated by handling or processing.
Ceramics
DISCUSSION—Common usage in powder technology (and British
F465 Practice for Developing Precision and Accuracy Data
Standard BS 2955) has the terms “aggregate” and “agglomerate”
on ASTM Method for the Analysis of Meat and Meat
interchanged in meaning from the definitions presented here, and care
Products (Withdrawn 1993)
must be taken to determine in context which definition is in use.
2.2 British Standard:
aggregate—a dense mass of particles held together by strong
BS 2955 Glossary of Terms Relating to Powders
intermolecular or atomic cohesive forces that is stable to
normal mixing techniques, including high-speed stirring and
ultrasonics.
This terminology is under the jurisdiction of ASTM Committee C21 on
Ceramic Whitewares and Related Products and is the direct responsibility of
alumina porcelain—see alumina porcelain under porcelain.
Subcommittee C21.01 on Editorial and Terminology.
Current edition approved Oct. 1, 2021. Published November 2021. Originally
alumina whiteware—see alumina whiteware under ceramic
approved in 1950. Last previous edition approved in 2020 as C242 – 20b. DOI:
whiteware.
10.1520/C0242-21.
andalusite—a polymorph, along with sillimanite and kyanite,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
of composition Al O ·SiO which on firing dissociates to
2 3 2
Standards volume information, refer to the standard’s Document Summary page on
yield principally mullite.
the ASTM website.
The last approved version of this historical standard is referenced on
apparent or pycnometric density—see apparent or pycno-
www.astm.org.
4 metric density under density.
Available from British Standards Institution (BSI), 389 Chiswick High Rd.,
London W4 4AL, U.K., http://www.bsigroup.com. apparent porosity—see apparent porosity under porosity.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C242 − 21
average particle size—a single value representing the entire bone china—a translucent china made from a ceramic white-
particle-size distribution. ware body composition containing a minimum of 25 % bone
ash.
DISCUSSION—It is essential to specify the basis under which the
average is obtained.
bright glaze—see bright glaze under glaze.
ball clay—a secondary clay, commonly characterized by the calcine—aceramicmaterialormixturefiredtolessthanfusion
presence of organic matter, high plasticity, high dry strength, for use as a constituent in a ceramic composition.
long vitrification range, and a light color when fired.
capillary action—thephenomenonofintrusionofaliquidinto
interconnected small voids, pores, and channels in a solid,
ball milling—a method of grinding and mixing material, with
resulting from surface tension.
or without liquid, in a rotating cylinder or conical mill
partially filled with grinding media such as balls or pebbles.
cassiterite (SnO )—an inorganic mineral of the tetragonal
form used as a source of tin and tin oxide.
basalt ware—a black unglazed vitreous ceramic ware having
the appearance of basalt rock.
casting—a process for forming ceramic ware by introducing a
body slip into a porous mold which absorbs sufficient water
Belleek china—a highly translucent whiteware composed of a
(or other liquid) from the slip to produce a semirigid article.
body containing a significant amount of frit and normally
drain casting (hollow casting)—forming ceramic ware by
having a luster glaze.
introducing a body slip into an open porous mold, and then
bentonite—a distinct type of fine-grained clay containing not
draining off the remaining slip when the case has reached the
less than 85 % montmorillionite clay having the formula
desired thickness.
(OH) Si Al O nH O and composed of units made up of
4 8 4 20 2
solid casting—forming ceramic ware by introducing a body
two silica tetrahedral sheets with a central alumina octahe-
slip into a porous mold which usually consists of two major
dral sheet.
sections,onesectionformingthecontouroftheoutsideandthe
other forming the contour of the inside of the ware and
beryllium oxide (beryllia) (BeO)—an inorganic material of
allowing a solid cast to form between the two mold faces.
exceptionally high thermal conductivity which is toxic in the
powder form.
ceramic article—an article having a glazed or unglazed body
of crystalline or partly crystalline structure, or of glass,
bias—a constant or systematic error, as opposed to a random
which body is produced from essentially inorganic, nonme-
error, manifesting itself as a persistent positive or negative
tallic substances and either is formed from a molten mass
deviation of the method average from the accepted reference
which solidifies on cooling, or is formed and simultaneously
value. E180; F465
or subsequently matured by the action of the heat.
binder—a cementing medium; either a material added to the
ceramic mosaic tile—an unglazed tile formed by either the
mixture to increase the green or dry strength as compacted,
1 3
dust-pressed or plastic method, usually ⁄4 to ⁄8 in. (6.4 to
and which may be expelled during sintering or calcining, or
9.5 mm) thick, and having a facial area of less than 6 in.
a material added to a mixture for the purpose of cementing 2
(39 cm ) and which is usually mounted on sheets approxi-
together particles.
mately 1 by 2 ft (0.3 by 0.6 m) to facilitate setting.
DISCUSSION—A binder may be either a permanent addition, or a
DISCUSSION—Ceramic mosaic tile may be of either porcelain or
temporary additive to a ceramic product.
natural clay composition and may be either plain or with an abrasive
mixture throughout.
bisque fire—see bisque fire under firing.
ceramic paste—a French term synonymous with “ceramic
blackbody—the ideal, perfect emitter and absorber of thermal
body.”
radiation which emits radiant energy at the maximum rate
possible,asaconsequenceofitstemperature,andabsorbsall
ceramic process—the production of articles or coatings from
incident radiation.
essentially inorganic, nonmetallic materials, the article or
coating being made permanent and suitable for utilitarian
blistering—the development during firing of enclosed or
anddecorativepurposesbytheactionofheatattemperatures
broken macroscopic vesicles or bubbles in a body, or in a
sufficient to cause sintering, solid-state reactions, bonding,
glaze or other coating.
or conversion partially or wholly to the glassy state.
bloating—substantial swelling produced by a heat treatment
ceramic whiteware—a fired ware consisting of a glazed or
that causes the formation of a vesicular structure.
unglazedceramicbodywhichiscommonlywhiteandoffine
texture, designating such product classifications as tile,
blunging—thewetprocessofblending,orsuspending ceramic
china, porcelain, semivitreous ware and earthenware.
material in liquid by agitation.
alumina whiteware—any ceramic whiteware in which alu-
body—the structural portion of a ceramic article, or the
mina (Al O ) is an essential crystalline phase.
2 3
material or mixture from which it is made.
cordierite whiteware—any ceramic whiteware in which
bone ash—calcined bone consisting essentially of calcium cordierite (2MgO·2Al O ·5SiO ) is the essential crystalline
2 3 2
phosphate. phase.
C242 − 21
forsterite whiteware—any ceramic whiteware in which for- color standard—a plaque or other physical standard of estab-
sterite (2MgO·SiO ) is the essential crystalline phase. lished color value, against which standardization of an
instrument is made.
steatite whiteware—any ceramic whiteware in which mag-
DISCUSSION—It may be a reference standard at a calibration
nesium metasilicate (MgO·SiO ) is the essential crystalline
laboratory, a transfer standard used to calibrate a particular instrument,
phase.
or a working standard for routine use.
titania whiteware—any ceramic whiteware in which titania
comminution—the act or process of reduction of particle size
(TiO ) is the essential crystalline phase.
with attendant increase in surface area and population of
zircon whiteware—any ceramic whiteware in which zircon
particles, usually but not necessarily by grinding, milling, or
(ZrO ·SiO ) is the essential crystalline phase.
2 2
pulverizing.
ceramics—a general term applied to the art or technique of
conductive ceramic tile—tile made from special body com-
producing articles by a ceramic process, or to the articles so
positions or by methods that result in specific properties of
produced.
electrical conductivity while retaining other normal physical
properties of ceramic tile.
chemical porcelain—see chemical porcelain under porcelain.
china—aglazedorunglazedvitreousceramicwhitewaremade
connected porosity—see connected porosity under porosity.
by the china process and used for nontechnical purposes,
cordierite porcelain—see cordierite porcelain under porce-
designating such products as dinnerware, sanitary ware, and
lain.
artware when they are vitreous. (See also bone china.)
cordierite whiteware—see cordierite whiteware under ce-
china clay—see kaolin. ramic whiteware.
china process—the method of producing glazed ware by corundum—a naturally occurring hexagonal mineral of the
which the ceramic body is fired to maturity, following which compositionAl O ,whichcanalsobepreparedsynthetically
2 3
the glaze is applied and matured by firing at a lower to high purity; noted for its hardness (9 on Mohs scale) and
temperature. refractoriness (M.P. = 2045 °C).
DISCUSSION—It forms the gem varieties ruby and sapphire with
china sanitary ware (sanitary plumbing fixtures)—glazed,
appropriate impurities. It may contain associated minerals such as
vitrified whiteware fixtures having a sanitary service func-
diaspore or various silicates, or both. Commonly coarsely crystalline,
tion. sometimes microcrystalline.
chipping—the breaking off of a chip or flake from a ceramic covering power—the ability of a glaze to cover the surface of
body due primarily to the application of an external force. the fired ware uniformly and completely.
clay—a natural mineral agglomerate, consisting essentially of crawling—apartingandcontractionoftheglazeonthesurface
hydrousaluminumsilicates;plasticwhensufficientlywetted,
of ceramic ware during drying or firing, resulting in un-
rigid when dried en masse, and vitrified when fired to a glazed areas bordered by coalesced glaze.
sufficiently high temperature.
crazing—the cracking that occurs in fired glazes or other
clear glaze—see clear glaze under glaze.
ceramic coatings as a result of tensile stresses; may also
closed porosity—see closed porosity under porosity. occur in the surface portion of uncoated (unglazed) white-
coefficient of friction—the ratio of the parallel component of
ware bodies.
force required to overcome or have a tendency to overcome
crystalline glaze—see crystalline glaze under glaze.
the resistance to relative motion of two surfaces in physical
deagglomeration—the process of breaking down, usually by
contactonewithanother,butotherwiseunconstrained,tothe
physicalmeans,themassesofparticlesthatareheldtogether
normal component of the force; usually the force caused by
byrelativelyweakcohesiveforcesresultinginafinalsystem
gravity; applied through the object which tends to cause the
of aggregates or primary particles, or both.
friction.
deairing—the process of removing entrapped air, or absorbed
color difference—(1) the magnitude and character of the
airfromamassorslurry,usuallybyapplicationofavacuum.
difference between two colors, described by such terms as
redder, bluer, lighter, darker, grayer, or cleaner; (2) the
decorated—adorned, embellished, or made more attractive by
magnitude and direction of the difference between a sample
means of color or surface detail.
and a standard, computed from tristimulus values, or chro-
decorating fire—see decorating fire under firing.
maticity coordinates and luminance factor, by means of a
decoration:
specified set of color difference equations.
inglaze decoration—a ceramic decoration applied on the
color space—a three dimensional arrangement for represent-
surface of an unfired glaze and matured with the glaze.
ing all possible colors; for example, in the color space
overglaze decoration—a ceramic or metallic decoration
defined by the color scales L, a, and b used to describe the
applied and fired on the previously glazed surface of ceramic
color of opaque specimens, scale L is a measure of lightness,
ware.
a is a measure of redness (plus) or greenness (minus), and b
is a measure of yellowness (plus) or blueness (minus). polychrome decoration—a multicolor decoration.
C242 − 21
underglaze decoration—a ceramic decoration applied di- dispersion—in a fine particle suspension, the condition which
rectlyonthesurfaceofceramicwareandsubsequentlycovered results when a stable suspension of particles is achieved by
with a transparent glaze. physical or chemical means in which no evidence of
reflocculation or reagglomeration of the particles is ob-
deflocculate—toseparateagglomeratesinaslurrybychemical
served.
and physical means to achieve and maintain particle-to-
dolomite—the double carbonate of lime and magnesia having
particle separation.
the general formula CaCO ·MgCO .
DISCUSSION—A surface-active wetting agent (cationic, anionic, or
3 3
nonionic type) to coat the particle surface with like ionic charges to
drag—the resistance to shrinkage of the foot or base of a
induce repulsion of the surfaces is usually effective.
ceramic article during drying or firing as a result of friction
deformation eutectic—see eutectic, deformation. with the setter, slab, or sagger on which it rests.
delft ware—a calcareous earthenware having an opaque white
drain casting—see drain casting under casting.
glaze and monochrome overglaze decorations. (Originated
draining—in ceramic manufacture, the process of removing
in Delft, Holland.)
excess slip from dipped or cast items by gravity flow.
density:
dry edging—rough edges and corners of glazed ceramic ware
absolute or true density—the weight divided by the volume
caused by insufficient glaze coating.
excluding open and closed pores.
dry mix—see dry process under process.
apparent or pycnometric density—the weight divided by the
dry pressing—see dry pressing under pressing.
volume excluding open pores, but including closed pores.
dry process—see dry process under process.
drying—removal by evaporation, of uncombined water or
tap density—the apparent density of a powdered or granu-
lated material resulting when the receptacle containing the other volatile substance from a ceramic raw material or
product, usually expedited by low-temperature heating.
material is vibrated or tapped under standard or specified
conditions.
dunting—the cracking that occurs in fired ceramic bodies as a
result of thermally induced stresses.
diameter:
arithmetic mean diameter—that diameter located at the
dynamic coefficient of friction—the ratio of the parallel
centroid of the distribution of size.
component of force applied to a moving body that maintains
constant relative motion of two surfaces in physical contact
equivalent diameter (sphere)—the diameter of a theoretical
one with another, but otherwise unconstrained, to the normal
sphere of a material which under identical physical conditions
component of the force; usually the force caused by gravity;
yieldsthesamevalueoftheparticularfinenesscharacteristicas
applied to the body under clean, dry conditions.
the actual irregularly shaped dispersed particle of the same
material.
earthenware—a glazed or unglazed nonvitreous ceramic
median diameter—that diameter at which the area under the whiteware.
curve of size versus frequency is divided into two equal parts.
eggshelling—the texture of a fired glaze similar in appearance
to the surface of an eggshell.
diatomaceous earth—see diatomite.
diatomite (diatomaceous earth)—amorphous lightweight si-
electrical porcelain—vitrified whiteware having an electrical
liceous material having the theoretical formula SiO ·nH O,
2 2 insulating function.
occurring naturally as the fossil remains of tiny plants
embossed—decorated in relief on the surface of the ware.
termed diatoms; also known as kiesel-guhr, tripolite, and
infusorial earth. embossment—a decoration in relief or excised on the ware
surface.
dilatometer—aninstrumenttomeasurethechangeinlengthof
a specimen as a function of temperature, usually to obtain a emissivity—the ratio of the radiation given off by the surface
of a body to the radiation given off by a perfect black body
coefficient of thermal expansion.
at the same temperature.
dilatometric softening point—temperature when a specimen
engobe—aslipcoatingappliedtoaceramicbodyforimparting
in a dilatometer starts to deform. Defined, by convention, as
color, opacity, or other characteristics, and subsequently
a viscosity of 10 Pa.
covered with a glaze.
dinnerware—ceramic whiteware made in a given pattern and
equilibrium eutectic—see eutectic, equilibrium.
in a full line of articles comprising a dinner service.
equivalent diameter (sphere)—see equivalent diameter
dispersant—an additive, usually a polyelectrolyte, that causes (sphere) under diameter.
suspended particles to act independently, overcoming van equivalent spherical diameter—see equivalent diameter
der Waals attractive forces between particles. (sphere) under diameter.
C242 − 21
DISCUSSION—Flocculates are usually formed in a gas or liquid
eutectic:
suspension, and those formed in a liquid can generally be broken up by
deformation eutectic—the composition within a system of
gentle shaking or stirring.
two or more components that, on heating under specified
conditions, develops sufficient liquid to cause deformation at
fluorite (CaF ) (fluorspar)—an inorganic mineral of the
the minimum temperature.
isometric form, used as a source of fluorine for fluxing of
glasses, and glazes.
equilibrium eutectic—the composition within any system of
two or more crystalline phases that melts completely at the
flux—a substance that promotes fusion in a given ceramic
minimum temperature, or the temperature at which such a
mixture.
composition melts.
forming—the shaping or molding of ceramic ware.
2 2
faience mosaics—faiencetilethatarelessthan6in. (39cm )
5 3
forsterite (2MgO·SiO )—a magnesium silicate mineral, usu-
in facial area, usually ⁄16 to ⁄8 in. (8 to 9.5 mm) thick, and
ally produced synthetically as a ceramic raw material; may
usually mounted to facilitate installation.
be a reaction-produced phase in fired ceramics.
faience tile—glazed or unglazed tile, generally made by the
forsterite porcelain—see fosterite porcelain under porcelain.
plastic process, showing characteristic variations in the face,
forsterite whiteware—see fosterite whiteware under ceramic
edges, and glaze that give a handicrafted, nonmechanical,
whiteware.
decorative effect.
free moisture—thatwater,whichisnotchemicallybound,and
faience ware—formerly a decorated earthenware with an
that is loosely bound to a material, but which can be
opaque glaze, but currently designating a decorated earthen-
removed by drying at 105 °C, for a time to achieve constant
ware having a transparent glaze.
weight, expressed as a percent of the initial weight of the
material.
feldspar—a mineral aggregate consisting chiefly of
DISCUSSION—There are a few materials in which chemically bound
microcline, albite, or anorthite or combination thereof.
water volatilizes below 105 °C.
fineness—a measurement number designating the particle size
friction—the resistance developed between the physical
of a material, usually reported as percent passing a screen of
contacting, but otherwise unconstrained, surfaces of two
a particular standard size.
bodies when there is movement or tendancy for movement
of one body relative to the other parallel to the plane of
fines—the portions of a powder composed of particles smaller
contact. (See also coefficient of friction, dynamic coeffi-
than a specified size.
cient of friction, in service coefficient of friction, static
fire—see bisque fire; decorating fire; glost fire; single fire
coefficient of friction.)
under firing.
frit—a product made by quenching and breaking up a glass of
firing—the controlled heat treatment of ceramic ware in a kiln
a specific composition, used customarily used as a compo-
orfurnace,duringtheprocessofmanufacture,todevelopthe
nent of a glaze, body, or porcelain enamel.
desired properties.
bisque fire—the process of kiln-firing ceramic ware before fritted glaze—see fritted glaze under glaze.
glazing. fusion—theprocessofmelting;usuallytheresultofinteraction
of two or more materials.
decorating fire—the process of firing ceramic or metallic
decorations on the surface of glazed ceramic ware.
glaze—a ceramic coating matured to the glassy state on a
formed ceramic article, or the material or mixture from
firing curve—a diagram or table showing the time and
which the coating is made.
temperature planned or experienced by ware going through a
firing operation.
bright glaze—a colorless or colored ceramic glaze having
high gloss.
firing cycle—the time required for one complete firing
operation (cold-to-cold).
clear glaze—a colorless or colored transparent ceramic
glaze.
firing range—the range of firing temperature within which a
ceramic composition develops properties which render it
crystalline glaze—a glaze containing macroscopic crystals.
commercially useful.
fritted glaze—a glaze in which a part or all of the fluxing
glost fire—the process of kiln-firing bisque ware to which
constituents are prefused.
glaze has been applied.
leadless glaze—a ceramic coating matured to a glassy state
single fire—the process of maturing an unfired ceramic body
on a formed article, or the material or the mixture from which
and its glaze in one firing operation.
the coating is made, to which no lead has been deliberately
added.
flexure strength—see modulus of rupture.
DISCUSSION—This does not imply that the glaze is nontoxic or that it
flocculate—a grouping of primary particles, aggregates, or
contains no lead. Because of plant practices and conditions, a small
agglomerates having weaker bonding than either the aggre-
percentage of lead, 0.1 to 0.2 % (by dry weight), expressed as lead
gate or agglomerate structures. monoxide, may be present.
C242 − 21
mat glaze—a colorless or colored ceramic glaze having low hollow casting—see drain casting under casting.
gloss. hot pressing—see hot pressing under pressing.
hue—the attribute of color perception by means of which a
opaque glaze—a nontransparent colored or colorless glaze.
color is judged to be red, orange, yellow, green, blue, purple,
raw glaze—a glaze compounded primarily from raw
or intermediate between adjacent pairs of these, considered
constituents, that is, containing no prefused materials.
inaclosedring,redandpurplebeinganadjacentpair(white,
semi-mat glaze—a colorless or colored glaze having moder-
gray, and black possess no hue).
ate gloss.
ilmenite—a mineral having the theoretical composition
slip glaze—a glaze consisting primarily of a readily fusible
FeO·TiO used principally in the production of titanium
clay or silt.
oxide.
vellum glaze—a semi-mat glaze having a satin-like appear-
impervious—that degree of vitrification evidenced visually by
ance.
complete resistance to dye penetration.
glaze fit—thestressrelationshipbetweentheglazeandbodyof
DISCUSSION—The term impervious generally signifies zero
a fired ceramic product. absorption, except for floor and wall tile which are considered
“impervious” up to 0.5 % water absorption.
glazed ceramic mosaic tile—ceramic mosaic tile with glazed
in service coefficient of friction—a coefficient of friction
faces.
measured under a specified condition of use, which may not
glazed tile—tile with a fused impervious facial finish com-
be clean and dry, and hence, not a property of the ceramic
posed of ceramic materials, fused with the body of the tile
surface.
which may be a nonvitreous, semivitreous, vitreous, or
DISCUSSION—For example, measurement of a ceramic tile coated
impervious body resulting in a surface that may be clear,
with grease is a measurement of the grease-tile system and not a
property of the ceramic tile.
white, or colored.
glazed interior tile—a glazed tile with a body that is suitable
incised—decorated by cutting or indenting the ware surface.
for interior use and which is usually nonvitreous, and is not
inglaze decoration—see inglaze decoration under decora-
required or expected to withstand excessive impact or be
tion.
subject to freezing and thawing conditions.
ironstone ware (stone china, white granite ware)—historic
glazed tile, extra duty glaze—tile with a durable glaze that is
terms for a durable English earthenware.
suitable for light-duty floors and all other surfaces on interiors
jasper ware—a vitreous, opaque, colored, unglazed ceramic
where there is no excessive abrasion or impact.
ware having white or contrasting relief decorations and
glossy, or bright glaze—a glaze which exhibits essentially full
containing a substantial amount of barite.
specular reflection.
jiggering—forming ceramic ware from a plastic body by
glost fire—see glost fire under firing.
differential rotation of a profile tool and mold, the mold
granulation—controlled agglomeration to improve the han-
having the contour of one surface of the ware and the profile
dling of fine powders, usually through mechanical means, to
tool that of the other surface.
produce nearly spherical powders that flow well.
kaolin (china clay)—arefractoryclayconsistingessentiallyof
grindability:
minerals of the kaolin group and which fires to a white or
absolute grindability index—a characteristic number ex-
nearly white color.
pressed as the change in specific surface area of a material per
unit of time in a specific comminution system. knockings—the oversize residue obtained in screening a
ceramic slip.
relative grindability index—a characteristic number ex-
pressed as the change in specific surface area or other criteria
kyanite (Al O ·SiO )—the most abundant of the mineral
2 3 2
such as particle size or fineness of a material per unit of time,
polymorphs that include andalusite and sillimanite, com-
mill revolutions or other standard with respect to a known
monly used as a source of mullite in ceramics.
standard sample in a specific comminution system.
laser light scattering—a phenomenon suitable for the mea-
DISCUSSION—Grindability is an intrinsic property of material hard-
surement of particle size in that particles illuminated by a
ness or friability that may be experimentally determined by measuring
the change in specifi
...

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: C242 − 20b C242 − 21
Standard Terminology of
Ceramic Whitewares and Related Products
This standard is issued under the fixed designation C242; 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 pertains to the terminology used in ceramic whitewares and related products.
1.2 Words adequately defined in standard dictionaries are not included. Included are words that are peculiar to this industry.
Double words, hyphenated words, or phrases are listed alphabetically under the first word; additional important words are
cross-referenced.
1.3 For definitions of terms relating to surface imperfections on ceramics, refer to Terminology F109.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
D1129 Terminology Relating to Water
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
(Withdrawn 2009)
F109 Terminology Relating to Surface Imperfections on Ceramics
F465 Practice for Developing Precision and Accuracy Data on ASTM Method for the Analysis of Meat and Meat Products
(Withdrawn 1993)
2.2 British Standard:
BS 2955 Glossary of Terms Relating to Powders
3. Terminology
absolute or true density—see absolute or true density under density.
absorbance—the logarithm of that fraction of an incident light beam that is dissipated in the sample, being neither transmitted
nor reflected.
This terminology is under the jurisdiction of ASTM Committee C21 on Ceramic Whitewares and Related Products and is the direct responsibility of Subcommittee
C21.01 on on Editorial and Terminology.
Current edition approved Sept. 1, 2020Oct. 1, 2021. Published October 2020November 2021. Originally approved in 1950. Last previous edition approved in 2020 as
C242 – 20a.C242 – 20b. DOI: 10.1520/C0242-20B.10.1520/C0242-21.
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.
The last approved version of this historical standard is referenced on www.astm.org.
Available from British Standards Institution (BSI), 389 Chiswick High Rd., London W4 4AL, U.K., http://www.bsigroup.com.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C242 − 21
absorbed moisture—water held mechanically in the material and having physical properties not substantially different from
ordinary water at the same temperature and pressure.
absorption—(1) the relationship of the weight of the water absorbed by a ceramic specimen, subjected to prescribed immersion
procedure, to the weight of the dry specimen; (2) the capacity of a substance to take up a substance, usually a liquid or gas, with
the formation of an apparently homogeneous mixture.
adsorption—the capacity of a substance to accept and retain on its surface a layer of another substance, usually a gas or a liquid.
agglomerate—a jumbled mass or collection of two or more particles or aggregates, or a combination thereof, held together by
relatively weak cohesive forces caused by weak chemical bonding or an electrostatic surface charge generated by handling or
processing.
DISCUSSION—
Common usage in powder technology (and British Standard BS 2955) has the terms “aggregate” and “agglomerate” interchanged in meaning from the
definitions presented here, and care must be taken to determine in context which definition is in use.
aggregate—a dense mass of particles held together by strong intermolecular or atomic cohesive forces that is stable to normal
mixing techniques, including high-speed stirring and ultrasonics.
alumina porcelain—see alumina porcelain under porcelain.
alumina whiteware—see alumina whiteware under ceramic whiteware.
andalusite—a polymorph, along with sillimanite and kyanite, of composition Al O ·SiO which on firing dissociates to yield
2 3 2
principally mullite.
apparent or pycnometric density—see apparent or pycnometric density under density.
apparent porosity—see apparent porosity under porosity.
average particle size—a single value representing the entire particle-size distribution.
DISCUSSION—
It is essential to specify the basis under which the average is obtained.
ball clay—a secondary clay, commonly characterized by the presence of organic matter, high plasticity, high dry strength, long
vitrification range, and a light color when fired.
ball milling—a method of grinding and mixing material, with or without liquid, in a rotating cylinder or conical mill partially
filled with grinding media such as balls or pebbles.
basalt ware—a black unglazed vitreous ceramic ware having the appearance of basalt rock.
Belleek china—a highly translucent whiteware composed of a body containing a significant amount of frit and normally having
a luster glaze.
bentonite—a distinct type of fine-grained clay containing not less than 85 % montmorillionite clay having the formula
(OH) Si Al O nH O and composed of units made up of two silica tetrahedral sheets with a central alumina octahedral sheet.
4 8 4 20 2
beryllium oxide (beryllia) (BeO)—an inorganic material of exceptionally high thermal conductivity which is toxic in the
powder form.
C242 − 21
bias—a constant or systematic error, as opposed to a random error, manifesting itself as a persistent positive or negative
deviation of the method average from the accepted reference value. E180,; F465
binder—a cementing medium; either a material added to the mixture to increase the green or dry strength as compacted, and
which may be expelled during sintering or calcining, or a material added to a mixture for the purpose of cementing together
particles.
DISCUSSION—
A binder may be either a permanent addition, or a temporary additive to a ceramic product.
bisque fire—see bisque fire under firing.
blackbody—the ideal, perfect emitter and absorber of thermal radiation which emits radiant energy at the maximum rate
possible, as a consequence of its temperature, and absorbs all incident radiation.
blistering—the development during firing of enclosed or broken macroscopic vesicles or bubbles in a body, or in a glaze or other
coating.
bloating—substantial swelling produced by a heat treatment that causes the formation of a vesicular structure.
blunging—the wet process of blending, or suspending ceramic material in liquid by agitation.
body—the structural portion of a ceramic article, or the material or mixture from which it is made.
bone ash—calcined bone consisting essentially of calcium phosphate.
bone china—a translucent china made from a ceramic whiteware body composition containing a minimum of 25 % bone ash.
bright glaze—see bright glaze under glaze.
calcine—a ceramic material or mixture fired to less than fusion for use as a constituent in a ceramic composition.
capillary action—the phenomenon of intrusion of a liquid into interconnected small voids, pores, and channels in a solid,
resulting from surface tension.
cassiterite (SnO )—an inorganic mineral of the tetragonal form used as a source of tin and tin oxide.
casting—a process for forming ceramic ware by introducing a body slip into a porous mold which absorbs sufficient water (or
other liquid) from the slip to produce a semirigid article.
drain casting (hollow casting)—forming ceramic ware by introducing a body slip into an open porous mold, and then draining
off the remaining slip when the case has reached the desired thickness.
solid casting—forming ceramic ware by introducing a body slip into a porous mold which usually consists of two major sections,
one section forming the contour of the outside and the other forming the contour of the inside of the ware and allowing a solid
cast to form between the two mold faces.
ceramic article—an article having a glazed or unglazed body of crystalline or partly crystalline structure, or of glass, which
body is produced from essentially inorganic, nonmetallic substances and either is formed from a molten mass which solidifies
on cooling, or is formed and simultaneously or subsequently matured by the action of the heat.
C242 − 21
1 3
ceramic mosaic tile—an unglazed tile formed by either the dust-pressed or plastic method, usually ⁄4 to ⁄8 in. (6.4 to 9.5 mm)
2 2
thick, and having a facial area of less than 6 in. (39 cm ) and which is usually mounted on sheets approximately 1 by 2 ft (0.3
by 0.6 m) to facilitate setting.
DISCUSSION—
Ceramic mosaic tile may be of either porcelain or natural clay composition and may be either plain or with an abrasive mixture throughout.
ceramic paste—a French term synonymous with “ceramic body.”
ceramic process—the production of articles or coatings from essentially inorganic, nonmetallic materials, the article or coating
being made permanent and suitable for utilitarian and decorative purposes by the action of heat at temperatures sufficient to
cause sintering, solid-state reactions, bonding, or conversion partially or wholly to the glassy state.
ceramic whiteware—a fired ware consisting of a glazed or unglazed ceramic body which is commonly white and of fine texture,
designating such product classifications as tile, china, porcelain, semivitreous ware and earthenware.
alumina whiteware—any ceramic whiteware in which alumina (Al O ) is an essential crystalline phase.
2 3
cordierite whiteware—any ceramic whiteware in which cordierite (2MgO·2Al O ·5SiO ) is the essential crystalline phase.
2 3 2
forsterite whiteware—any ceramic whiteware in which forsterite (2MgO·SiO ) is the essential crystalline phase.
steatite whiteware—any ceramic whiteware in which magnesium metasilicate (MgO·SiO ) is the essential crystalline phase.
titania whiteware—any ceramic whiteware in which titania (TiO ) is the essential crystalline phase.
zircon whiteware—any ceramic whiteware in which zircon (ZrO ·SiO ) is the essential crystalline phase.
2 2
ceramics—a general term applied to the art or technique of producing articles by a ceramic process, or to the articles so
produced.
chemical porcelain—see chemical porcelain under porcelain.
china—a glazed or unglazed vitreous ceramic whiteware made by the china process and used for nontechnical purposes,
designating such products as dinnerware, sanitary ware, and artware when they are vitreous. (See also bone china.)
china clay—see kaolin.
china process—the method of producing glazed ware by which the ceramic body is fired to maturity, following which the glaze
is applied and matured by firing at a lower temperature.
china sanitary ware (sanitary plumbing fixtures)—glazed, vitrified whiteware fixtures having a sanitary service function.
chipping—the breaking off of a chip or flake from a ceramic body due primarily to the application of an external force.
clay—a natural mineral agglomerate, consisting essentially of hydrous aluminum silicates; plastic when sufficiently wetted, rigid
when dried en masse, and vitrified when fired to a sufficiently high temperature.
clear glaze—see clear glaze under glaze.
closed porosity—see closed porosity under porosity.
coefficient of friction—the ratio of the parallel component of force required to overcome or have a tendency to overcome the
resistance to relative motion of two surfaces in physical contact one with another, but otherwise unconstrained, to the normal
component of the force; usually the force caused by gravity; applied through the object which tends to cause the friction.
color difference—(1) the magnitude and character of the difference between two colors, described by such terms as redder,
C242 − 21
bluer, lighter, darker, grayer, or cleaner; (2) the magnitude and direction of the difference between a sample and a standard,
computed from tristimulus values, or chromaticity coordinates and luminance factor, by means of a specified set of color
difference equations.
color space—a three dimensional arrangement for representing all possible colors; for example, in the color space defined by
the color scales L, a, and b used to describe the color of opaque specimens, scale L is a measure of lightness, a is a measure
of redness (plus) or greenness (minus), and b is a measure of yellowness (plus) or blueness (minus).
color standard—a plaque or other physical standard of established color value, against which standardization of an instrument
is made.
DISCUSSION—
It may be a reference standard at a calibration laboratory, a transfer standard used to calibrate a particular instrument, or a working standard for routine
use.
comminution—the act or process of reduction of particle size with attendant increase in surface area and population of particles,
usually but not necessarily by grinding, milling, or pulverizing.
conductive ceramic tile—tile made from special body compositions or by methods that result in specific properties of electrical
conductivity while retaining other normal physical properties of ceramic tile.
connected porosity—see connected porosity under porosity.
cordierite porcelain—see cordierite porcelain under porcelain.
cordierite whiteware—see cordierite whiteware under ceramic whiteware.
corundum—a naturally occurring hexagonal mineral of the composition Al O , which can also be prepared synthetically to high
2 3
purity; noted for its hardness (9 on Mohs scale) and refractoriness (M.P. = 2045 °C).
DISCUSSION—
It forms the gem varieties ruby and sapphire with appropriate impurities. It may contain associated minerals such as diaspore or various silicates, or
both. Commonly coarsely crystalline, sometimes microcrystalline.
covering power—the ability of a glaze to cover the surface of the fired ware uniformly and completely.
crawling—a parting and contraction of the glaze on the surface of ceramic ware during drying or firing, resulting in unglazed
areas bordered by coalesced glaze.
crazing—the cracking that occurs in fired glazes or other ceramic coatings as a result of tensile stresses; may also occur in the
surface portion of uncoated (unglazed) whiteware bodies.
crystalline glaze—see crystalline glaze under glaze.
deagglomeration—the process of breaking down, usually by physical means, the masses of particles that are held together by
relatively weak cohesive forces resulting in a final system of aggregates or primary particles, or both.
deairing—the process of removing entrapped air, or absorbed air from a mass or slurry, usually by application of a vacuum.
decorated—adorned, embellished, or made more attractive by means of color or surface detail.
decorating fire—see decorating fire under firing.
decoration:
inglaze decoration—a ceramic decoration applied on the surface of an unfired glaze and matured with the glaze.
C242 − 21
overglaze decoration—a ceramic or metallic decoration applied and fired on the previously glazed surface of ceramic ware.
polychrome decoration—a multicolor decoration.
underglaze decoration—a ceramic decoration applied directly on the surface of ceramic ware and subsequently covered with a
transparent glaze.
deflocculate—to separate agglomerates in a slurry by chemical and physical means to achieve and maintain particle-to-particle
separation.
DISCUSSION—
A surface-active wetting agent (cationic, anionic, or nonionic type) to coat the particle surface with like ionic charges to induce repulsion of the surfaces
is usually effective.
deformation eutectic—see eutectic,deformation.
delft ware—a calcareous earthenware having an opaque white glaze and monochrome overglaze decorations. (Originated in
Delft, Holland.)
density:
absolute or true density—the weight divided by the volume excluding open and closed pores.
apparent or pycnometric density—the weight divided by the volume excluding open pores, but including closed pores.
tap density—the apparent density of a powdered or granulated material resulting when the receptacle containing the material is
vibrated or tapped under standard or specified conditions.
diameter:
arithmetic mean diameter—that diameter located at the centroid of the distribution of size.
equivalent diameter (sphere)—the diameter of a theoretical sphere of a material which under identical physical conditions yields
the same value of the particular fineness characteristic as the actual irregularly shaped dispersed particle of the same material.
median diameter—that diameter at which the area under the curve of size versus frequency is divided into two equal parts.
diatomaceous earth—see diatomite.
diatomite (diatomaceous earth)—amorphous lightweight siliceous material having the theoretical formula SiO ·nH O,
2 2
occurring naturally as the fossil remains of tiny plants termed diatoms; also known as kiesel-guhr,tripolite, and infusorial earth.
dilatometer—an instrument to measure the change in length of a specimen as a function of temperature, usually to obtain a
coefficient of thermal expansion.
dilatometric softening point—temperature when a specimen in a dilatometer starts to deform. Defined, by convention, as a
viscosity of 10 Pa.
dinnerware—ceramic whiteware made in a given pattern and in a full line of articles comprising a dinner service.
dispersant—an additive, usually a polyelectrolyte, that causes suspended particles to act independently, overcoming van der
Waals attractive forces between particles.
dispersion—in a fine particle suspension, the condition which results when a stable suspension of particles is achieved by
physical or chemical means in which no evidence of reflocculation or reagglomeration of the particles is observed.
dolomite—the double carbonate of lime and magnesia having the general formula CaCO ·MgCO .
3 3
drag—the resistance to shrinkage of the foot or base of a ceramic article during drying or firing as a result of friction with the
setter, slab, or sagger on which it rests.
C242 − 21
drain casting—see drain casting under casting.
draining—in ceramic manufacture, the process of removing excess slip from dipped or cast items by gravity flow.
dry edging—rough edges and corners of glazed ceramic ware caused by insufficient glaze coating.
dry mix—see dry process under process.
dry pressing—see dry pressing under pressing.
dry process—see dry process under process.
drying—removal by evaporation, of uncombined water or other volatile substance from a ceramic raw material or product,
usually expedited by low-temperature heating.
dunting—the cracking that occurs in fired ceramic bodies as a result of thermally induced stresses.
dynamic coefficient of friction—the ratio of the parallel component of force applied to a moving body that maintains constant
relative motion of two surfaces in physical contact one with another, but otherwise unconstrained, to the normal component of
the force; usually the force caused by gravity; applied to the body under clean, dry conditions.
earthenware—a glazed or unglazed nonvitreous ceramic whiteware.
eggshelling—the texture of a fired glaze similar in appearance to the surface of an eggshell.
electrical porcelain—vitrified whiteware having an electrical insulating function.
embossed—decorated in relief on the surface of the ware.
embossment—a decoration in relief or excised on the ware surface.
emissivity—the ratio of the radiation given off by the surface of a body to the radiation given off by a perfect black body at the
same temperature.
engobe—a slip coating applied to a ceramic body for imparting color, opacity, or other characteristics, and subsequently covered
with a glaze.
equilibrium eutectic—see eutectic,equilibrium.
equivalent diameter (sphere)—see equivalent diameter (sphere) under diameter.
equivalent spherical diameter—see equivalent diameter (sphere) under diameter.
C242 − 21
eutectic:
deformation eutectic—the composition within a system of two or more components that, on heating under specified conditions,
develops sufficient liquid to cause deformation at the minimum temperature.
equilibrium eutectic—the composition within any system of two or more crystalline phases that melts completely at the
minimum temperature, or the temperature at which such a composition melts.
2 2
5 3
faience mosaics—faience tile that are less than 6 in. (39 cm ) in facial area, usually ⁄16 to ⁄8 in. (8 to 9.5 mm) thick, and
usually mounted to facilitate installation.
faience tile—glazed or unglazed tile, generally made by the plastic process, showing characteristic variations in the face, edges,
and glaze that give a handicrafted, nonmechanical, decorative effect.
faience ware—formerly a decorated earthenware with an opaque glaze, but currently designating a decorated earthenware
having a transparent glaze.
feldspar—a mineral aggregate consisting chiefly of microcline, albite, or anorthite or combination thereof.
fineness—a measurement number designating the particle size of a material, usually reported as percent passing a screen of a
particular standard size.
fines—the portions of a powder composed of particles smaller than a specified size.
fire—see bisque fire; decorating fire; glost fire; single fire under firing.
firing—the controlled heat treatment of ceramic ware in a kiln or furnace, during the process of manufacture, to develop the
desired properties.
bisque fire—the process of kiln-firing ceramic ware before glazing.
decorating fire—the process of firing ceramic or metallic decorations on the surface of glazed ceramic ware.
firing curve—a diagram or table showing the time and temperature planned or experienced by ware going through a firing
operation.
firing cycle—the time required for one complete firing operation (cold-to-cold).
firing range—the range of firing temperature within which a ceramic composition develops properties which render it
commercially useful.
glost fire—the process of kiln-firing bisque ware to which glaze has been applied.
single fire—the process of maturing an unfired ceramic body and its glaze in one firing operation.
flexure strength—see modulus of rupture.
flocculate—a grouping of primary particles, aggregates, or agglomerates having weaker bonding than either the aggregate or
agglomerate structures.
DISCUSSION—
Flocculates are usually formed in a gas or liquid suspension, and those formed in a liquid can generally be broken up by gentle shaking or stirring.
fluorite (CaF ) (fluorspar)—an inorganic mineral of the isometric form, used as a source of fluorine for fluxing of glasses, and
glazes.
flux—a substance that promotes fusion in a given ceramic mixture.
forming—the shaping or molding of ceramic ware.
C242 − 21
forsterite (2MgO·SiO )—a magnesium silicate mineral, usually produced synthetically as a ceramic raw material; may be a
reaction-produced phase in fired ceramics.
forsterite porcelain—see fosterite porcelain under porcelain.
forsterite whiteware—see fosterite whiteware under ceramic whiteware.
free moisture—that water, which is not chemically bound, and that is loosely bound to a material, but which can be removed
by drying at 105 °C, for a time to achieve constant weight, expressed as a percent of the initial weight of the material.
DISCUSSION—
There are a few materials in which chemically bound water volatilizes below 105 °C.
friction—the resistance developed between the physical contacting, but otherwise unconstrained, surfaces of two bodies when
there is movement or tendancy for movement of one body relative to the other parallel to the plane of contact. (See also
coefficient of friction,dynamic coefficient of friction,in service coefficient of friction,static coefficient of friction.)
frit—a product made by quenching and breaking up a glass of a specific composition, used customarily used as a component
of a glaze, body, or porcelain enamel.
fritted glaze—see fritted glaze under glaze.
fusion—the process of melting; usually the result of interaction of two or more materials.
glaze—a ceramic coating matured to the glassy state on a formed ceramic article, or the material or mixture from which the
coating is made.
bright glaze—a colorless or colored ceramic glaze having high gloss.
clear glaze—a colorless or colored transparent ceramic glaze.
crystalline glaze—a glaze containing macroscopic crystals.
fritted glaze—a glaze in which a part or all of the fluxing constituents are prefused.
leadless glaze—a ceramic coating matured to a glassy state on a formed article, or the material or the mixture from which the
coating is made, to which no lead has been deliberately added.
DISCUSSION—
This does not imply that the glaze is nontoxic or that it contains no lead. Because of plant practices and conditions, a small percentage of lead, 0.1
to 0.2 % (by dry weight), expressed as lead monoxide, may be present.
mat glaze—a colorless or colored ceramic glaze having low gloss.
opaque glaze—a nontransparent colored or colorless glaze.
raw glaze—a glaze compounded primarily from raw constituents, that is, containing no prefused materials.
semi-mat glaze—a colorless or colored glaze having moderate gloss.
slip glaze—a glaze consisting primarily of a readily fusible clay or silt.
vellum glaze—a semi-mat glaze having a satin-like appearance.
glaze fit—the stress relationship between the glaze and body of a fired ceramic product.
glazed ceramic mosaic tile—ceramic mosaic tile with glazed faces.
glazed tile—tile with a fused impervious facial finish composed of ceramic materials, fused with the body of the tile which may
be a nonvitreous, semivitreous, vitreous, or impervious body resulting in a surface that may be clear, white, or colored.
glazed interior tile—a glazed tile with a body that is suitable for interior use and which is usually nonvitreous, and is not required
or expected to withstand excessive impact or be subject to freezing and thawing conditions.
C242 − 21
glazed tile, extra duty glaze—tile with a durable glaze that is suitable for light-duty floors and all other surfaces on interiors
where there is no excessive abrasion or impact.
glossy, or bright glaze—a glaze which exhibits essentially full specular reflection.
glost fire—see glost fire under firing.
granulation—controlled agglomeration to improve the handling of fine powders, usually through mechanical means, to produce
nearly spherical powders that flow well.
grindability:
absolute grindability index—a characteristic number expressed as the change in specific surface area of a material per unit of
time in a specific comminution system.
relative grindability index—a characteristic number expressed as the change in specific surface area or other criteria such as
particle size or fineness of a material per unit of time, mill revolutions or other standard with respect to a known standard sample
in a specific comminution system.
DISCUSSION—
Grindability is an intrinsic property of material hardness or friability that may be experimentally determined by measuring the change in specific
surface area, ΔA , generated per unit of grinding time, t; the grindability index being determined from the slope of the plot of ΔA in m /g versus
s s
grinding time, t, in hours or other unit of time.
healing power—the ability of a glaze to heal surface blemishes during firing.
heat work—acombination of temperature (mostly) and time necessary to cause the deformation of a standard ceramic body (a
pyrometric cone), expressed as cone number.
hollow casting—see drain casting under casting.
hot pressing—see hot pressing under pressing.
hue—the attribute of color perception by means of which a color is judged to be red, orange, yellow, green, blue, purple, or
intermediate between adjacent pairs of these, considered in a closed ring, red and purple being an adjacent pair (white, gray, and
black possess no hue).
ilmenite—a mineral having the theoretical composition FeO·TiO used principally in the production of titanium oxide.
impervious—that degree of vitrification evidenced visually by complete resistance to dye penetration.
DISCUSSION—
The term impervious generally signifies zero absorption, except for floor and wall tile which are considered “impervious” up to 0.5 % water absorption.
in service coefficient of friction—a coefficient of friction measured under a specified condition of use, which may not be clean
and dry, and hence, not a property of the ceramic surface.
DISCUSSION—
For example, measurement of a ceramic tile coated with grease is a measurement of the grease-tile system and not a property of the ceramic tile.
incised—decorated by cutting or indenting the ware surface.
inglaze decoration—see inglaze decoration under decoration.
ironstone ware (stone china, white granite ware)—historic terms for a durable English earthenware.
jasper ware—a vitreous, opaque, colored, unglazed ceramic ware having white or contrasting relief decorations and containing
a substantial amount of barite.
C242 − 21
jiggering—forming ceramic ware from a plastic body by differential rotation of a profile
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