ASTM C839-82(2015)

Standard Test Method for Compressive Stress of Porcelain Enamels by Loaded-Beam Method

SIGNIFICANCE AND USE
4.1 All porcelain enamel coatings or glass coatings are by necessity under some degree of compression at room temperature. The desired degree of compression or stress depends upon the type of ware and the end use of the item. Some method of determining relative compressive stress of enamels is necessary to establish the suitability of an enamel for a proposed application.
SCOPE
1.1 This test method covers the measurement of the compressive stresses (Note 1) developed by fired porcelain enamels using the loaded-beam method.  
Note 1: Although some may interpret the calculations that are used in this test method as indicating compressive load, it is commonly referred to as compressive stress within the porcelain enamel industry.  
1.2 This test method is limited to the use of the loaded-beam method. However, this method includes charts (Fig. 1 and Fig. 2) that provide for conversion of loaded-beam test results to warp and ring stress values.  
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2015
• ICS: 25.220.50 - Enamels
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.12 - Materials for Porcelain Enamel and Ceramic-Metal Systems

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C839 − 82 (Reapproved 2015)
Standard Test Method for
Compressive Stress of Porcelain Enamels by Loaded-Beam
Method
This standard is issued under the fixed designation C839; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Manymethodsandtestshavebeenusedintheindustrytodeterminetherelativecompressivestress
of porcelain enamel ground coats and cover coats. Three methods have been most commonly used.
Theyareloaded-beam,warp,andsplit-ringmethods.Intheloaded-beammethodthemeasureofstress
is the load required to bring a specimen back to a plane after it has been bowed by controlled
application of the enamel under test to one side of the specimen. The degree of the deflection of a
specimen from a plane caused by controlled application of enamel to one side is the indicating
measure of stress in the warp test. The indicating measurement in the split-ring test is the force
required to just open a split ring after controlled application of test enamel to the outside surface of
a ring.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the measurement of the com-
pressivestresses(Note1)developedbyfiredporcelainenamels A424SpecificationforSteel,Sheet,forPorcelainEnameling
using the loaded-beam method.
3. Terminology
NOTE 1—Although some may interpret the calculations that are used in
3.1 Description of Term Specific to This Standard
thistestmethodasindicatingcompressiveload,itiscommonlyreferredto
as compressive stress within the porcelain enamel industry.
3.2 compressive stress or stress—a term used to designate
1.2 Thistestmethodislimitedtotheuseoftheloaded-beam
the degree of compression that exists in a porcelain enamel on
method. However, this method includes charts (Fig. 1 and Fig.
steel after processing.
2) that provide for conversion of loaded-beam test results to
warp and ring stress values. 4. Significance and Use
1.3 The values stated in inch-pound units are to be regarded 4.1 All porcelain enamel coatings or glass coatings are by
as standard. The values given in parentheses are mathematical necessity under some degree of compression at room tempera-
conversions to SI units that are provided for information only ture.Thedesireddegreeofcompressionorstressdependsupon
and are not considered standard. the type of ware and the end use of the item. Some method of
determining relative compressive stress of enamels is neces-
1.4 This standard does not purport to address all of the
sary to establish the suitability of an enamel for a proposed
safety concerns, if any, associated with its use. It is the
application.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Apparatus
bility of regulatory limitations prior to use.
5.1 Furnace, suitable for simultaneous firing of at least six
1 by 12-in. (25 by 305-mm) specimens in vertical hanging
position.
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
5.2 Firing Rack, suitable for furnace.
Materials for Porcelain Enamel and Ceramic-Metal Systems.
This test method was developed at the National Bureau of Standards under the
sponsorship of the Porcelain Enamel Institute, Inc., and was published as PEI
Technical Publication No. T-30 (1973). For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2015. Published June 2015. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approvedin1976.Lastpreviouseditionapprovedin2010asC839–82(2010).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0839-82R15. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C839 − 82 (2015)
Metric Equivalents
in. mm in. mm
0.02 0.51 0.10 2.54
0.04 1.02 0.12 3.05
0.06 1.52 0.14 3.56
0.08 2.03
FIG. 1 Conversion Chart for Loaded-Beam Stress to Warp Stress
FIG. 2 Conversion Chart for Loaded-Beam Stress to Ring Stress
C839 − 82 (2015)
5.3 Loaded-Beam Test Apparatus (see Fig. 3 and Fig. 4). 5.7 Stencil Brush.
5.4 Metric Weights, slotted, 1 to 500 g.
5.8 Fluorescent Light Fixture with diffusion panel and
adjustable support.
5.5 Laboratory Balance, accurate to 10 mg with necessary
weights (1 to 100 g).
6. Test Specimens
1 15
5.6 Brushing Template, 2 ⁄16 by 10 ⁄16 in. (52 by 278 mm)
(seeFig.5foroneexampleofachievingthedesiredendresult). 6.1 Six specimens are required for each enamel tested.
Metric Equivalents
in. mm in. mm
1 3
⁄4 6.35 1 ⁄4 44.45
3 1
⁄8 9.53 2 ⁄16 52.39
7 11
⁄16 11.11 3 ⁄16 93.68
⁄2 12.7 4 101.6
5 5
⁄8 15.88 4 ⁄16 109.54
0.866 22.0 8 ⁄8 219.08
1 25.4 10 ⁄16 277.81
1 ⁄4 31.75 12 304.8
1 ⁄2 38.1 16 406.4
1 ⁄16 42.86
FIG. 3 Loaded-Beam Test Apparatus
C839 − 82 (2015)
FIG. 4 Loaded-Beam Test Apparatus
NOTE 1—See Fig. 3 for metric equivalents.
FIG. 5 Brushing Template
6.2 Specimens 1 by 12 in. (25 by 305 mm) shall be cut by permanently identified by metal stamping on the scribed side
shearing from flat sheets of 20-gage Commercial QualityType while being supported on an anvil (see Fig. 6).
II enameling iron (see Specification A424) with thickness
0.036 6 0.002 in. (0.91 6 0.05 mm). The 12-in. dimension 7. Procedure
should be cut perpendicular to the direction of rolling of sheet.
7.1 Application of Ground Coat to Test Strips:
Care should be exercised to prevent formation of burrs during
7.1.1 Subject the specimens to a pickle procedure normal
shearing. Burrs that are formed may be removed by carefully
for ground coat application. Pickle in a suspended vertical
filing edges or by lightly touching edges to a sanding belt.
position to prevent distortion.
Since opposing sides of the sheet may produce slightly
7.1.2 Measure and record metal thickness of the test speci-
differentresults,onesideofthesheetshouldbescribedinsuch
mens.
a manner that the scribe mark will appear about 1 in. from one
end of the resulting strips after shearing. A ⁄4-in. (6.35-mm) 7.1.3 Apply a medium high-temperature ground coat (1520
diameter hole should be punched in one end of the specimen to1540°F(825to840°C))byspraying.Withscribedsidesup,
for hanging purposes during drying and firing. The center of first spray the back sides of strips to give 1.5 g dry weight per
the hole should be on the center line ⁄16 in. (11 mm) from the strip. Dry and cool. Reverse the strips and spray a like amount
end of the specimen. Specimens should be numbered for on the face side. Dry and cool. Use a relatively dry spray to
identification during the testing procedure. They may be avoid formation of beads on the edges of the strips (Note 2).
C839 − 82 (2015)
NOTE 1—Wipe all bisque cover coat enamel from sides, ends, and back of ground coated test sample before firing cover coat.
NOTE 2—See Fig. 3 for metric equivalents.
FIG. 6 Detail of Test Specimen
7.1.4 Fire the strips in a vertical hanging position at the 7.3.3 Measure and record the uncorrected compressive load
optimum time and temperatur
...

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: C839 − 82 (Reapproved 2010) C839 − 82 (Reapproved 2015)
Standard Test Method for
Compressive Stress of Porcelain Enamels by Loaded-Beam
Method
This standard is issued under the fixed designation C839; 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
Many methods and tests have been used in the industry to determine the relative compressive stress
of porcelain enamel ground coats and cover coats. Three methods have been most commonly used.
They are loaded-beam, warp, and split-ring methods. In the loaded-beam method the measure of stress
is the load required to bring a specimen back to a plane after it has been bowed by controlled
application of the enamel under test to one side of the specimen. The degree of the deflection of a
specimen from a plane caused by controlled application of enamel to one side is the indicating
measure of stress in the warp test. The indicating measurement in the split-ring test is the force
required to just open a split ring after controlled application of test enamel to the outside surface of
a ring.
1. Scope
1.1 This test method covers the measurement of the compressive stresses (Note 1) developed by fired porcelain enamels using
the loaded-beam method.
NOTE 1—Although some may interpret the calculations that are used in this test method as indicating compressive load, it is commonly referred to as
compressive stress within the porcelain enamel industry.
1.2 This test method is limited to the use of the loaded-beam method. However, this method includes charts (Fig. 1 and Fig.
2) that provide for conversion of loaded-beam test results to warp and ring stress values.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.4 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A424 Specification for Steel, Sheet, for Porcelain Enameling
3. Terminology
3.1 Description of Term Specific to This Standard
3.2 compressive stress or stress—a term used to designate the degree of compression that exists in a porcelain enamel on steel
after processing.
This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
Materials for Porcelain Enamel and Ceramic-Metal Systems.
This test method was developed at the National Bureau of Standards under the sponsorship of the Porcelain Enamel Institute, Inc., and was published as PEI Technical
Publication No. T-30 (1973).
Current edition approved April 1, 2010May 1, 2015. Published June 2010June 2015. Originally approved in 1976. Last previous edition approved in 20052010 as
C839 – 82 (2005). (2010). DOI: 10.1520/C0839-82R10.10.1520/C0839-82R15.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C839 − 82 (2015)
Metric Equivalents
in. mm in. mm
0.02 0.51 0.10 2.54
0.04 1.02 0.12 3.05
0.06 1.52 0.14 3.56
0.08 2.03
FIG. 1 Conversion Chart for Loaded-Beam Stress to Warp Stress
FIG. 2 Conversion Chart for Loaded-Beam Stress to Ring Stress
C839 − 82 (2015)
4. Significance and Use
4.1 All porcelain enamel coatings or glass coatings are by necessity under some degree of compression at room temperature.
The desired degree of compression or stress depends upon the type of ware and the end use of the item. Some method of
determining relative compressive stress of enamels is necessary to establish the suitability of an enamel for a proposed application.
5. Apparatus
5.1 Furnace, suitable for simultaneous firing of at least six 1 by 12-in. (25 by 305-mm) specimens in vertical hanging position.
5.2 Firing Rack, suitable for furnace.
5.3 Loaded-Beam Test Apparatus (see Fig. 3 and Fig. 4).
5.4 Metric Weights, slotted, 1 to 500 g.
5.5 Laboratory Balance, accurate to 10 mg with necessary weights (1 to 100 g).
1 15
5.6 Brushing Template, 2 ⁄16 by 10 ⁄16 in. (52 by 278 mm) (see Fig. 5 for one example of achieving the desired end result).
5.7 Stencil Brush.
5.8 Fluorescent Light Fixture with diffusion panel and adjustable support.
6. Test Specimens
6.1 Six specimens are required for each enamel tested.
6.2 Specimens 1 by 12 in. (25 by 305 mm) shall be cut by shearing from flat sheets of 20-gage Commercial Quality Type II
enameling iron (see Specification A424) with thickness 0.036 6 0.002 in. (0.91 6 0.05 mm). The 12-in. dimension should be cut
perpendicular to the direction of rolling of sheet. Care should be exercised to prevent formation of burrs during shearing. Burrs
that are formed may be removed by carefully filing edges or by lightly touching edges to a sanding belt. Since opposing sides of
the sheet may produce slightly different results, one side of the sheet should be scribed in such a manner that the scribe mark will
appear about 1 in. from one end of the resulting strips after shearing. A ⁄4-in. (6.35-mm) diameter hole should be punched in one
end of the specimen for hanging purposes during drying and firing. The center of the hole should be on the center line ⁄16 in. (11
mm) from the end of the specimen. Specimens should be numbered for identification during the testing procedure. They may be
permanently identified by metal stamping on the scribed side while being supported on an anvil (see Fig. 6).
7. Procedure
7.1 Application of Ground Coat to Test Strips:
7.1.1 Subject the specimens to a pickle procedure normal for ground coat application. Pickle in a suspended vertical position
to prevent distortion.
7.1.2 Measure and record metal thickness of the test specimens.
7.1.3 Apply a medium high-temperature ground coat (1520 to 1540 °F (825 to 840 °C)) by spraying. With scribed sides up, first
spray the back sides of strips to give 1.5 g dry weight per strip. Dry and cool. Reverse the strips and spray a like amount on the
face side. Dry and cool. Use a relatively dry spray to avoid formation of beads on the edges of the strips (Note 2).
7.1.4 Fire the strips in a vertical hanging position at the optimum time and temperature for the ground coat. The preferred
procedure is to fire multiples of six simultaneously. Cool in a suspended position, avoiding drafts or forced cooling.
7.1.5 Weigh and record the weight of each strip to the nearest 0.01 g.
7.1.6 Place each strip on the test apparatus with the scribed side down.
7.1.7 Measure and record the ground coat residual load, which is the weight in grams required to cause the strip to just rest on
the three knife edges of the fixture. Discard any strips having zero or negative stress (reverse bow) or having positive load of more
than 50 g.
NOTE 2—More consistently uniform and usable specimens will result
...