ASTM C424-93(2006)
(Test Method)Standard Test Method for Crazing Resistance of Fired Glazed Whitewares by Autoclave Treatment
Standard Test Method for Crazing Resistance of Fired Glazed Whitewares by Autoclave Treatment
SIGNIFICANCE AND USE
This test method is particularly useful for porous materials that can exhibit moisture expansion.
This test method is a primary test method that is suitable for use in specifications, quality control, and research and development. It can also serve as a referee test method in purchasing contracts or agreements.
SCOPE
1.1 This test method covers the determination of the crazing resistance of fired glazed whitewares using the autoclave treatment and under the conditions specified in this test method.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:C424–93 (Reapproved 2006)
Standard Test Method for
Crazing Resistance of Fired Glazed Whitewares by
Autoclave Treatment
This standard is issued under the fixed designation C424; 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 larger specimens, specifically tile products, five samples will
suffice and these may be cut to facilitate entry into the
1.1 This test method covers the determination of the crazing
autoclave. However, all cut pieces should be as large as
resistance of fired glazed whitewares using the autoclave
possible and all cut pieces are to be tested.
treatment and under the conditions specified in this test
method.
5. Procedure
1.2 The values stated in inch-pound units are to be regarded
5.1 Placement of Specimens in the Autoclave—Place a
as the standard. The values given in parentheses are for
sufficientamountofdistilledwaterintheautoclavesothatafter
information only.
the test a slight excess of water will remain. Place all
1.3 This standard does not purport to address all of the
specimens on a suitable support at least 2 in. (51 mm) above
safety concerns, if any, associated with its use. It is the
the water line within the autoclave at room temperature. Fasten
responsibility of the user of this standard to establish appro-
the autoclave head securely in place.
priate safety and health practices and determine the applica-
5.2 Operation of Autoclave—Gradually heat the water in
bility of regulatory limitations prior to use.
the bottom of the autoclave. Keep the blow-off valve open for
2. Significance and Use several minutes after steam begins to escape, thereby expelling
most of the air. After closing the blow-off valve, increase the
2.1 This test method is particularly useful for porous mate-
steam pressure at a uniform rate until the desired pressure is
rials that can exhibit moisture expansion.
reached within a period of not less than 45 min nor exceeding
2.2 This test method is a primary test method that is suitable
1 h. Apply sufficient heat to maintain the indicated pressure
for use in specifications, quality control, and research and
constant (62 psi (14 kPa)) for an additional hour. Shut off the
development. It can also serve as a referee test method in
heat source and release the steam pressure immediately by
purchasing contracts or agreements.
opening the blow-off valve.
3. Apparatus
5.2.1 If it is desirable to ascertain whether failure occurs as
a result of rehydration only, the blow-off valve should be
3.1 Autoclave—Anautoclavebuiltforasteampressureofat
cracked only and the steam released slowly over a period of 30
least 275 psi (1.9 MPa), and preferably with sufficient capacity
min. If this method of steam release is used, the report shall so
to contain at least ten specimens. The apparatus shall be
state.
equipped with a safety valve, a blow-off valve, pressure gage
5.3 Removal of Specimens from Autoclave—Loosen the
measuring pressure above atmospheric pressure with an accu-
autoclave head and allow the specimens to cool in place for 30
racy of 65 psi (34 kPa), and a source of heat of sufficient
min. Remove the specimens and allow to cool at room
capacity to ensure a constant steam pressure within the
temperature for an additional 30 min before examination.
autoclave.
5.4 Examination of Specimens for Crazing Failures—Use
4. Number of Specimens
oblique lighting and the application of a suitable ink o
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