ASTM C632-88(2021)

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: C632 − 88 (Reapproved 2021)
Standard Test Method for
Reboiling Tendency of Sheet Steel for Porcelain Enameling
This standard is issued under the fixed designation C632; 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.
INTRODUCTION
The results of this test indicate whether or not a sheet steel will cause reboiling under one given set
of enameling conditions, and enable the enamel processor to establish a possible cause of
imperfections in the finished coating. This may be performed in any laboratory equipped for porcelain
enamel. It does not require facilities for metal surface preparation.
1. Scope 3.1.1 ground coat—a porcelain enamel applied directly to
the base metal to function as an intermediate layer between the
1.1 This test method covers the determination of whether a
metal and the cover coat (see Terminology C286).
sheet steel for porcelain enameling will reboil under a given set
of worse case conditions.
3.1.2 reboiling—gas evolution occurring and recurring dur-
ing repeated firing of the ground coat, sometimes a defect (see
1.2 The values stated in inch-pound units are to be regarded
Terminology C286).
as the standard. The values given in parentheses are for
information only.
3.1.3 slip (slurry)— a suspension of finely divided material
1.3 This standard does not purport to address all of the in liquid (see Terminology C286).
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 quarter lines—imaginary lines parallel to the direction
priate safety, health, and environmental practices and deter-
of rolling positioned at a distance from the sheet mill edge,
mine the applicability of regulatory limitations prior to use.
equal to one quarter of the sheet width.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Summary of Test Method
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.1 Both surfaces of sheet steel sample plates are subjected
mendations issued by the World Trade Organization Technical
to a cleaning treatment and are then porcelain enameled with a
Barriers to Trade (TBT) Committee.
sheet-steel, ground-coat type finish. Subsequent reheating at
various times is performed to reveal whether or not the steel
2. Referenced Documents
will cause reboiling. The presence or absence of reboiling is
2.1 ASTM Standards: determined by visual inspection.
C286 Terminology Relating to Porcelain Enamel and
Ceramic-Metal Systems 5. Significance and Use
5.1 The results of this test indicate whether or not a sheet
3. Terminology
steel will cause reboiling under one given set of enameling
3.1 Definitions:
conditions and enable the enamel processor to establish a
possible source of imperfections in the finished coating.
This test method is under the jurisdiction ofASTM Committee B08 on Metallic 5.2 This test method is normally used to test samples from
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
lots, coils, or lifts of sheet steel which for some reason,
Materials for Porcelain Enamel and Ceramic-Metal Systems.
production problems, defects evident on enameled parts, or
Current edition approved April 1, 2021. Published May 2021. Originally
production experience are suspected of causing defects in
approvedin1969.Lastpreviouseditionapprovedin2016asC632 – 88(2016).DOI:
10.1520/C0632-88R21.
enameled ware which have the appearance of reboiling. It is
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
often used to establish whether a problem exists with the bare
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
steel or other factors such as the porcelain enamel, processing
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. contamination, and so forth.
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C632 − 88 (2021)
6. Apparatus sufficient time to fuse the ground-coat enamel to the base
metal. This time and temperature should be that recommended
6.1 This test can be conducted in any laboratory equipped
by the porcelain enamel manufacturers for optimum adherence
for general porcelain enameling. It does not require facilities
(maturing temperature).
for metal surface preparation.
NOTE 1—Thin fired coatings of 2 ⁄2 to 3 mils (
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