ASTM C373-18(2023)

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: C373 − 18 (Reapproved 2023)
Standard Test Methods for
Determination of Water Absorption and Associated
Properties by Vacuum Method for Pressed Ceramic Tiles
and Glass Tiles and Boil Method for Extruded Ceramic Tiles
and Non-tile Fired Ceramic Whiteware Products
This standard is issued under the fixed designation C373; 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 4. Apparatus and Materials
1.1 These test methods covers procedures for determining
4.1 Balance or scale, of adequate capacity, suitable to weigh
water absorption, bulk density, apparent porosity, and apparent
accurately to 0.01 g (0.00002 lb).
specific gravity of non-tile fired unglazed ceramic whiteware
4.2 Oven, capable of maintaining a temperature of 150 °C 6
products, glazed or unglazed ceramic tiles, and glass tiles.
5 °C (302 °F 6 9 °F).
1.2 The values stated in metric units are normative. The
4.3 Wire Loop, Halter, or Basket, capable of supporting
values given in parentheses are mathematical conversions to
specimens under water for making suspended mass measure-
inch-pound units that are provided for information only and are
ments.
not normative.
4.4 Suspended Mass Container (if Determination of Sus-
1.3 This standard does not purport to address all of the
pended Mass is Desired)—A glass beaker or similar container
safety concerns, if any, associated with its use. It is the
of such size and shape that the sample, when suspended from
responsibility of the user of this standard to establish appro-
the balance by the wire loop, specified in 4.3, is completely
priate safety, health, and environmental practices and deter-
immersed in water with the sample and the wire loop com-
mine the applicability of regulatory limitations prior to use.
pletely free of contact with any part of the container.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.5 Stainless Steel Boiling Container, suitable for boiling
ization established in the Decision on Principles for the
water and with sufficient capacity to hold the test specimens
Development of International Standards, Guides and Recom-
and quantity of water specified in 6.2. The container shall be
mendations issued by the World Trade Organization Technical
equipped with a loose removable cover which does not allow
Barriers to Trade (TBT) Committee.
pressure to build.
2. Referenced Documents
4.6 Deionized (DI) or Distilled Water.
2.1 ASTM Standards:
4.7 Microfiber Cloth.
E691 Practice for Conducting an Interlaboratory Study to
4.8 Heat Source, such as a hot plate, burner, or equivalent to
Determine the Precision of a Test Method
heat the water to boiling.
3. Significance and Use
4.9 Desiccator—a sealed chamber containing desiccants
3.1 Measurement of density, porosity, and specific gravity is
which is of sufficient size and capacity to allow specimens to
a tool for determining the degree of maturation of a ceramic
cool while preventing the specimens from absorbing moisture
body, or for determining structural properties that may be
from ambient air.
required for a given application.
4.10 Pressure Vessel, capable of holding a vacuum of
91 kPa 6 5 kPa (26.9 inHg 6 1.5 inHg) below standard
These test methods is under the jurisdiction of ASTM Committee C21 on atmospheric pressure. The vessel shall be large enough to hold
Ceramic Whitewares and Related Products and is the direct responsibility of
the required number of tile samples and the necessary volume
Subcommittee C21.03 on Methods for Whitewares and Environmental Concerns.
of water to cover the tiles during testing. A modified 41.5 quart
Current edition approved March 1, 2023. Published March 2023. Originally
pressure cooker has been found to meet these requirements.
approved in 1955. Last previous edition approved in 2018 as C373 – 18. DOI:
10.1520/C0373-18R23.
4.11 Vacuum Pump, capable of achieving and holding the
Non-tile ceramic whitewares are ceramic whitewares as defined in ASTM
Terminology Standard C242, excluding ceramic tiles. required vacuum.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C373 − 18 (2023)
4.12 Gauge, capable of measuring the required vacuum.
Gauge shall be installed on a manifold connected directly to the
pressure vessel. Readings from any gauges present on the
pump are not acceptable forms of measurement.
4.13 Hoses, fittings, valves, solenoids, or combinations
thereof, assembled in such a way to allow manually or
automatic operation.
4.14 Timer, accurate to 1 second.
(a.) Equal Sides: x # 205 mm, , a = ⁄2 x (within 10 mm)
5. Test Specimens:
5.1 Non-tile Fired Ceramic Whitewares:
5.1.1 At least five representative test specimens shall be
selected that have not been previously tested. The specimens
shall be unglazed and shall have as much of the surface freshly
fractured as is practical. Sharp edges or corners shall be
removed. The specimens shall contain no cracks. The indi-
(b.) Unequal Sides: area # 420 cm , x > y, a = ⁄2 x (within 10 mm)
vidual test specimens shall weigh at least 50 g (0.11 lb).
FIG. 1 (a) & (b)
5.2 Ceramic Tiles and Glass Tiles:
5.2.1 Sampling shall be carried out in accordance with Table
1 and 5.2.2 through 5.2.8 based on the length (x), width (y),
and the area of the tiles to be tested (for irregularly shaped tiles,
205 mm by 205 mm (8 in. by 8 in.) portion, within 10 mm (0.4
see Note 1). Tiles and relevant specimens must contain no
in.), shall be cut from one corner of each specimen for testing
visible damage or cracks prior to testing and have not been
(see Fig. 2).
previously tested. Any loose or contaminating material shall be
2 2
5.2.4 For tiles greater than 420 cm (65 in. ), with 205 mm
removed. This includes any mesh, paper and adhesive that has
(8 in.) < x < 1000 mm (39 in.) and y ≤ 205 mm (8 in.), at least
been applied to mosaics. Cutting of specimens, as described in
five representative test specimens shall be selected. Each
the following sections, shall consist of scoring and snapping, or
specimen shall be cut once perpendicular to the longest side,
sawing when impossible to score and snap with conventional
such that a 205 mm (8 in.) portion, within 10 mm (0.4 in.), is
tile scoring equipment (as can be the case with some glass tiles
available for testing (see Fig. 3).
and textured and structured porcelain tiles).
2 2
5.2.5 For tiles greater than 420 cm (65 in. ), with x ≥
NOTE 1—For irregularly shaped tiles (hexagons, circles, and so forth),
1000 mm (39 in.) and y ≤ 205 mm (8 in.), at least five
consider the area of the minimum rectangle in which the tile can be fit.
representative test specimens shall be selected. Each specimen
2 2
5.2.2 For tiles less than or equal to 420 cm (65 in. ), at least shall be cut twice, once on each end, perpendicular to the
five representative test specimens shall be selected. Specimens longest side, such that two 205 mm (8 in.) portions within
shall be cut in half, within 10 mm (0.4 in.). Specimens shall be 10 mm (0.4 in.), one from each end, are available for testing
cut perpendicular to the longest side if the specimen has (see Fig. 4).
2 2
unequal sides. Select one half at random from each specimen 5.2.6 For tiles greater than 3600 cm (558 in. ), with x and
for testing (see Fig. 1a and Fig. 1b). y ≥ 410 mm (16 in.), at least three representative test speci-
2 2
5.2.3 For tiles greater than 420 cm (65 in. ) and less than or mens shall be selected. A 205 mm by 205 mm (8 in. by 8 in.)
2 2
equal to 3600 cm (558 in. ), with x and y > 205 mm (8 in.), at portion, within 10 mm (0.4 in.), shall be cut from each of the
least five representative test specimens shall be selected. A four corners of each specimen for testing (see Fig. 5).
TABLE 1 Sampling
# of
Reference Paragraph Total # Total #
Maximum Area Specimens per Tile
for Sample Cutting of Tiles of Specimens
to be Tested
2 2
Area # 420 cm (65 in. ) 5.2.2 1 5 5
2 2 2 2
420 cm (65 in. ) < Area # 3600 cm (558 in. ) 5.2.3 1 5 5
(with x and y > 205 mm [8 in.])
2 2
Area > 420 cm (65 in. ) 5.2.4 1 5 5
(with 205 mm [8 in.] < x < 1000 mm [39 in.] and
y # 205 mm [8 in.])
2 2
Area > 420 cm (65 in. ) 5.2.5 2 5 10
(x $ 1000 mm [39 in.] and y # 205 mm [8 in.])
2 2
Area > 3600 cm (558 in. ) 5.2.6 4 3 12
(with x and y $ 410 mm [16 in.])
2 2
Area > 3600 cm (558 in. ) 5.2.7 4 3 12
(with x $ 410 mm [16 in.] and
205 mm [8 in.] < y # 410 mm [16 in.])
C373 − 18 (2023)
6.2 Water Impregnation of Extruded Ceramic Tiles and
Non-tile Fired Ceramic Whiteware Products Using Boil
Method:
6.2.1 For Non-tile Fired Ceramic Whitewares—Bring DI or
distilled water to a boil in a stainless steel boiling container.
(Warning—Handling water at boiling or near boiling tempera-
ture can present a safety hazard. Wear appropriate personal
protective equipment.) Place the specimens in the boiling DI or
distilled water, and use setter pins, a rustproof rack, or
equivalent to separate the specimens from the bottom and sides
of the stainless steel boiling container and from each other. The
FIG. 2
DI or distilled water shall be unused and of sufficient quantity
2 2
x > 205 mm, y > 205 mm, 420 cm < area # 3600 cm ,
that the test specimens are fully submerged and the mass ratio
a = 205 mm (within 10 mm)
of water to test specimens is at least 3:1.
6.2.2 For Extruded Ceramic Tiles—Place the specimens in a
stainless steel boiling container of DI or distilled water at room
temperature, and use setter pins, a rustproof rack, or equivalent
to separate the specimens from the bottom and sides of the
stainless steel boiling container and from each other. The DI or
distilled water shall be unused and of sufficient quantity such
FIG. 3
that the test specimens are fully submerged and the mass ratio
205 mm < x < 1000 mm, y # 205 mm, area > 420 cm ,
of water to test specimens is at least 3:1. Bring the DI or
a = 205 mm (within 10 mm)
distilled water with submerged specimens to a boil in one hour
or less.
6.2.3 Boil the specimens for 5 h 6 5 min. Place a loose
2 2
cover over the container to minimize water loss through
5.2.7 For tiles greater than 3600 cm (558 in. ), with x ≥
evaporation. Test specimens shall be completely immersed in
410 mm (16 in.) and 205 mm (8 in.) < y ≤ 410 mm (16 in.), at
the boiling DI or distilled water throughout the duration of the
least three representative test specimens shall be selected. Each
5 h boil. Add DI or distilled water as needed to ensure the
specimen shall be cut twice, at each end, perpendicular to the
specimens are completely immersed at all times. Ensure that
longest side, to produce two 205 mm (8 in.) portions, within
the boil is maintained throughout the test and that the addition
10 mm (0.4 in.). Each such 205 mm (8 in.) portion shall be cut
of water does not hinder the boil. After the 5 h boil, allow the
a second time, in half, within 10 mm (0.4 in.) perpendicular to
specimens to continue to soak in the same DI or distilled water
the first cut (see Fig. 6). All four pieces from each specimen
in which they
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