ASTM C632-88(2021)

Standard Test Method for Reboiling Tendency of Sheet Steel for Porcelain Enameling

SIGNIFICANCE AND USE
5.1 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 source of imperfections in the finished coating.  
5.2 This test method is normally used to test samples from lots, coils, or lifts of sheet steel which for some reason, production problems, defects evident on enameled parts, or production experience are suspected of causing defects in enameled ware which have the appearance of reboiling. It is often used to establish whether a problem exists with the bare steel or other factors such as the porcelain enamel, processing contamination, and so forth.
SCOPE
1.1 This test method covers the determination of whether a sheet steel for porcelain enameling will reboil under a given set of worse case conditions.  
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 concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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: 31-Mar-2021
• ICS: 25.220.50 - Enamels
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.12 - Materials for Porcelain Enamel and Ceramic-Metal Systems

Relations

• Refers: ASTM C286-99(2009) - Standard Terminology Relating to Porcelain Enamel and Ceramic-Metal Systems
• Effective Date: 01-Sep-2009
• Refers: ASTM C286-99(2004) - Standard Terminology Relating to Porcelain Enamel and Ceramic-Metal Systems
• Effective Date: 01-Oct-2004
• Refers: ASTM C286-99 - Standard Terminology Relating to Porcelain Enamel and Ceramic-Metal Systems
• Effective Date: 10-Oct-1999

Overview

ASTM C632-88(2021): Standard Test Method for Reboiling Tendency of Sheet Steel for Porcelain Enameling is an internationally recognized standard developed by ASTM International. This document provides a reliable procedure for determining whether a sample of sheet steel will exhibit reboiling under specific enameling conditions. Reboiling is a defect where gas evolution and bubbling occur during or after the application of porcelain enamel, potentially leading to imperfections in the finished coating. Manufacturers, processors, and laboratories rely on this standard to diagnose sources of surface defects and maintain high product quality in porcelain-enameled steel goods.

Key Topics

• Reboiling Determination: The method assesses if the steel sample causes reboiling - visible as surface bubbles or blisters - during repeated firing of a porcelain enamel ground coat.
• Test Conditions: The procedure simulates worst-case enameling conditions, using standardized firing times and temperatures to prompt defect manifestation if present.
• Sample Selection: Steel samples for testing are taken from 'quarter lines,' ensuring representative coverage and exclusion of areas affected by rust or mill identification stamps.
• Visual Inspection: After enameling and firing cycles, the steel panels are visually examined for evidence of bubbling or surface blistering, which indicates a failure due to reboiling tendency.
• Quality Control: Results enable processors to determine if defects originate from the steel itself or from other factors such as enamel composition or processing contamination.

Applications

ASTM C632 plays a crucial role in the quality assurance processes for industries engaged in the manufacture of porcelain-enameled products, such as:

• Appliance Manufacturing: Ensuring steel components for stoves, refrigerators, washing machines, and other equipment are free from surface defects after enameling.
• Architectural Panels and Facades: Verifying the reliability of steel used in decorative and functional building elements that require a flawless, durable enamel finish.
• Industrial Equipment: Testing sheet steel intended for tanks, vessels, or laboratory ware where enamel coatings are used for corrosion resistance and hygiene.
• Material Procurement: Screening steel lots, coils, or lifts for suitability before committing to large-scale production, preventing costly rework or product recalls due to enamel blistering or bubbling.
• Failure Analysis: Troubleshooting production issues by distinguishing between steel-induced defects and those resulting from other process variables.

Related Standards

To ensure comprehensive quality and compatibility in porcelain enameling processes, consider these related ASTM standards:

• ASTM C286 - Terminology Relating to Porcelain Enamel and Ceramic-Metal Systems: Defines terms pertinent to enamel coatings, facilitating consistent communication and understanding within the industry.
• Other ASTM Coating Test Methods: For more thorough testing, referencing complementary standards concerning enamel adhesion, thickness measurement, and resistance to chemical or mechanical stresses may be beneficial.

Practical Value

Using ASTM C632 helps manufacturers and processors:

• Identify Defects Early: Quickly detect reboiling problems in steel before full-scale production, reducing waste and improving efficiency.
• Maintain Product Standards: Support adherence to stringent product quality demands in consumer goods and critical infrastructure applications.
• Optimize Supply Chains: Collaborate effectively with suppliers by utilizing an internationally accepted method for steel evaluation, enabling transparent and reliable procurement.

This standard underpins robust quality management for anyone involved in producing porcelain-enameled steel goods, contributing to durable, attractive, and defect-free products.

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: 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 [e-mail]. 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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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 (
...