ASTM D1474/D1474M-13(2018)

Standard Test Methods for Indentation Hardness of Organic Coatings

SIGNIFICANCE AND USE
4.1 Indentation hardness measurements have proven to be useful in rating coatings on rigid substrates for their resistance to mechanical abuse, such as that produced by blows, gouging, and scratching. These measurements do not necessarily characterize the resistance to mechanical abuse of coatings that are required to remain intact when deformed.
SCOPE
1.1 These test methods cover the determination of the indentation hardness of organic materials such as dried paint, varnish, and lacquer coatings, when applied to an acceptable plane rigid surface, for example, metal or glass.  
1.2 Two methods are covered as follows:    
Sections  
Method A—Knoop Indentation Hardness  
6 – 12  
Method B—Pfund Indentation Hardness  
13 – 19  
1.3 Method A, which has the greater precision, provides hardness values in terms of Knoop Hardness Number (KHN). Method B provides hardness in terms of Pfund Hardness Number (PHN). Although the hardness value scales of these methods differ, the methods agree in the ranking of coating hardness.  
1.4 Test Method A of these test methods is similar in content (but not technically equivalent) to ISO 6441-1 and ISO 6441-2.  
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.6 This standard does not purport to address 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.  
1.7 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: Historical
• Publication Date: 31-Oct-2018
• ICS: 25.220.60 - Organic coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.23 - Physical Properties of Applied Paint Films

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: D1474/D1474M − 13 (Reapproved 2018)
Standard Test Methods for
Indentation Hardness of Organic Coatings
This standard is issued under the fixed designation D1474/D1474M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
1.1 These test methods cover the determination of the 2.1 ASTM Standards:
indentation hardness of organic materials such as dried paint, D823 Practices for Producing Films of Uniform Thickness
varnish, and lacquer coatings, when applied to an acceptable of Paint, Coatings and Related Products on Test Panels
plane rigid surface, for example, metal or glass. D1005 Test Method for Measurement of Dry-Film Thick-
ness of Organic Coatings Using Micrometers
1.2 Two methods are covered as follows:
D7091 Practice for Nondestructive Measurement of Dry
Sections
Film Thickness of Nonmagnetic Coatings Applied to
Method A—Knoop Indentation Hardness 6 – 12
Method B—Pfund Indentation Hardness 13 – 19 Ferrous Metals and Nonmagnetic, Nonconductive Coat-
ings Applied to Non-Ferrous Metals
1.3 Method A, which has the greater precision, provides
E384 Test Method for Microindentation Hardness of Mate-
hardness values in terms of Knoop Hardness Number (KHN).
rials
Method B provides hardness in terms of Pfund Hardness
2.2 Other Standards:
Number (PHN). Although the hardness value scales of these
ISO 6441-1 Paints and Varnishes—Determination of micro-
methods differ, the methods agree in the ranking of coating
indentation hardness—Part 1: Knoop hardness by mea-
hardness.
surement of the indentation length
1.4 Test Method A of these test methods is similar in content
ISO 6441-2 Paints and Varnishes—Determination of micro-
(but not technically equivalent) to ISO 6441-1 and ISO 6441-2.
indentation hardness—Part 2: Knoop hardness by mea-
1.5 The values stated in either SI units or inch-pound units
surement of the indentation depth under load
are to be regarded separately as standard. The values stated in
3. Terminology
each system may not be exact equivalents; therefore, each
system shall be used independently of the other. Combining
3.1 Definitions:
values from the two systems may result in non-conformance
3.1.1 indentation hardness, n—the resistance to penetration
with the standard.
by an indenter.
1.6 This standard does not purport to address the safety
3.1.2 Knoop indenter, n—a pyramidal diamond of pre-
concerns, if any, associated with its use. It is the responsibility
scribed dimensions.
of the user of this standard to establish appropriate safety,
3.1.3 Pfund indenter, n—hemispherical quartz or sapphire
health, and environmental practices and determine the appli-
indenter of prescribed dimensions.
cability of regulatory limitations prior to use.
3.1.4 Knoop hardness number, KHN, n—the indentation
1.7 This international standard was developed in accor-
hardness determined with a Knoop indenter, and calculated as
dance with internationally recognized principles on standard-
follows:
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- KHN5 L/A 5 L/l C (1)
p p
mendations issued by the World Trade Organization Technical
where:
Barriers to Trade (TBT) Committee.
L = load applied to the indenter, kg,
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and are the direct For referenced ASTM standards, visit the ASTM website, www.astm.org, or
responsibility of Subcommittee D01.23 on Physical Properties of Applied Paint contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Films. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2018. Published November 2018. Originally the ASTM website.
approved in 1957. Last previous edition approved in 2013 as D1474/D1474M – 13. Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/D1474_D1474M-13R18. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1474/D1474M − 13 (2018)
indenter into contact with the test surface with negligible
l = measured length of long diagonal of the indentation,
impact, apply the selected full load, maintain it for 18 6 0.5 s,
mm,
and withdraw the indenter.
C = indenter constant relating l to A , and
p p
A = projected area of indentation, mm .
p
7.2 Knoop Indenter—The Knoop indenter is a pyramidal
3.1.5 Pfund hardness number, PHN, n—the indentation
diamond with included longitudinal angles of 172° 30' and
hardness determined with a Pfund indenter, and calculated as included transverse angle of 130° 0'.
follows:
NOTE 1—The ratio of the long to the short diagonal of the impression
2 2
is approximately 7:1; the ratio of the long diagonal to the depth of
PHN5 L/A 5 4L/πd 5 1.27 ~L/d ! (2)
penetration is approximately 30:1.
where:
7.3 Microscope—The microscope shall have a filar microm-
L = load/kg applied to the indenter, kg,
eter eyepiece and sufficient objectives to permit the measure-
A = area of projected indentation, mm , and
ment of the length of impression to within 61 %. The
d = diameter of projected indentation, mm.
specimen shall be firmly supported on a movable micrometer
stage attached to the microscope.
4. Significance and Use
4.1 Indentation hardness measurements have proven to be
8. Calibration
useful in rating coatings on rigid substrates for their resistance
8.1 Adjust the illumination in the microscope to give
to mechanical abuse, such as that produced by blows, gouging,
maximum contrast when viewing an indentation.
and scratching. These measurements do not necessarily char-
8.2 By means of a calibrated scale, determine the factor for
acterize the resistance to mechanical abuse of coatings that are
each microscope objective that converts the filar scale units of
required to remain intact when deformed.
the eyepiece to millimetres.
5. Test Specimens
8.3 With a 25-g load on the indenter, determine the KHN of
5.1 The substrate for the coating shall be an acceptable
a calibrated standard (Note 2) with an assigned value not
plane rigid surface such as glass or metal.
greater than 50 KHN. If the obtained value is within 65 % of
the assigned value, the instrument is considered to be in
5.2 The coating thickness on any one panel shall be uniform
calibration.
within 3 µm [0.1 mil]. Coatings to be compared shall be of
equal thickness within 5 µm [0.2 mil]. For maximum accuracy,
NOTE 2—A suitable source of standard reference materials in this
the minimum permissible coating thickness shall be such that
hardness range is available from the U.S. National Institute for Standards
and Technology. By agreement of the parties concerned, a stable
the depth of indentation does not exceed three fourths of the
specimen (such as an aged coating or a baked enamel applied to a flat
coating thickness, to minimize the effect of the substrate.
substrate) could be used to calibrate the participating hardness testers.
5.3 At least three replicate specimens shall be tested for
9. Procedure
each coating to be evaluated.
5.4 Coatings should be applied in accordance with Practices 9.1 Unless otherwise specified, make the hardness determi-
nations at 23 6 2°C [73.5 6 3.50°F] and 50 6 5 % relative
D823 and their dry film thickness should be measured in
accordance with Test Methods D1005 or D7091. humidity after equilibrating the specimens under these condi-
tions for at least 24 hours.
5.5 From precoated sheets cut at least three specimens. Use
only plane (flat) sheets and round the edges slightly. The 9.2 Rigidly attach the specimen to the movable stage so that
the surface to be measured is normal to the direction of
coating shall be free of oil and other foreign matter. Measure
indentation. Mount the panel so that is cannot move with
the film thickness as in 5.4.
respect to the stage in any direction during the test.
METHOD A—KNOOP INDENTATION HARDNESS
9.3 Use the microscope to select an area of the test specimen
that is free of surface irregularities and imperfections. Place
6. Summary of Method
this area under the indenter by means of the movable microm-
6.1 This method consists of applying a load to the surface of
eter stage.
a coating by means of a pyramidal shaped diamond having
NOTE 3—If good impressions cannot be obtained because of the
specified face angles, and converting the measurements of the
roughness of the surface of the specimen, gently polish the surface with
resultant permanent impression to a hardness number.
No. 400 carborundum and finish off with jewelers rouge before making the
impression.
7. Apparatus
9.4 Present the apparatus to apply a load that permits the
7.1 Hardness Tester , consisting of a load applicator, a
length of identification to be read accurately but does not cause
Knoop indenter, and a microscope fitted with a movable
the depth of indentation to exceed three-quarters of the coating
micrometer stage. The apparatus shall mechanically bring the
film thickness. Start the test cycle so that the indenter is
A hardness tester meeting the apparatus requirements for this method is the
Tukon Microhardness Tester, available from the Wilson Instruments, Inc., Division Available from National Institute of Standards and Technology (NIST), 100
of Instron, 100 Royall St., Canton, MA 02021. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
D1474/D1474M − 13 (2018)
mechanically brought into contact with the mounted specimen 11.1.2 Mean film thickness of each specimen, based on the
under a load of 25 g and full load is applied, maintained for 18 measurements made at the points of indentation,
6 0.5 seconds, and removed. For maximum accuracy, ensure 11.1.3 Specimen preparation and conditioning techniques
that the indenter has not penetrated the coating to a depth used,
beyond three-fourths of the coating thickness. This is
...

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: D1474/D1474M − 13 D1474/D1474M − 13 (Reapproved 2018)
Standard Test Methods for
Indentation Hardness of Organic Coatings
This standard is issued under the fixed designation D1474/D1474M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*Scope
1.1 These test methods cover the determination of the indentation hardness of organic materials such as dried paint, varnish,
and lacquer coatings, when applied to an acceptable plane rigid surface, for example, metal or glass.
1.2 Two methods are covered as follows:
Sections
Method A—Knoop Indentation Hardness 6 – 12
Method B—Pfund Indentation Hardness 13 – 19
1.3 Method A, which has the greater precision, provides hardness values in terms of Knoop Hardness Number (KHN). Method
B provides hardness in terms of Pfund Hardness Number (PHN). Although the hardness value scales of these methods differ, the
methods agree in the ranking of coating hardness.
1.4 Test Method A of these test methods is similar in content (but not technically equivalent) to ISO 6441-1and 6441-1 and ISO
6441-2.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.6 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the
user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
D823 Practices for Producing Films of Uniform Thickness of Paint, Coatings and Related Products on Test Panels
D1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
D7091 Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals
and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals
E384 Test Method for Microindentation Hardness of Materials
2.2 Other Standards:
ISO 6441-1 Paints and Varnishes—Determination of micro-indentation hardness—Part 1: Knoop hardness by measurement of
the indentation length
ISO 6441-2 Paints and Varnishes—Determination of micro-indentation hardness—Part 2: Knoop hardness by measurement of
the indentation depth under load
These test methods are under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and are the direct responsibility of
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved Nov. 1, 2013Nov. 1, 2018. Published December 2013November 2018. Originally approved in 1957. Last previous edition approved in 20082013
as D1474 – 98 (2008).D1474/D1474M – 13. DOI: 10.1520/D1474_D1474M-13.10.1520/D1474_D1474M-13R18.
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.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1474/D1474M − 13 (2018)
3. Terminology
3.1 Definitions:
3.1.1 indentation hardness, n—the resistance to penetration by an indenter.
3.1.2 Knoop indenter, n—a pyramidal diamond of prescribed dimensions.
3.1.3 Pfund indenter, n—hemispherical quartz or sapphire indenter of prescribed dimensions.
3.1.4 Knoop hardness number, KHN, n—the indentation hardness determined with a Knoop indenter, and calculated as follows:
KHN 5 L/A 5 L/l C (1)
p p
where:
L = load applied to the indenter, kg,
l = measured length of long diagonal of the indentation, mm,
C = indenter constant relating l to A , and
p p
A = projected area of indentation, mm .
p
3.1.5 Pfund hardness number, PHN, n—the indentation hardness determined with a Pfund indenter, and calculated as follows:
2 2
PHN 5 L/A 5 4L/πd 5 1.27 ~L/d ! (2)
where:
L = load/kg applied to the indenter, kg,
A = area of projected indentation, mm , and
d = diameter of projected indentation, mm.
where:
L = load/kg applied to the indenter, kg,
A = area of projected indentation, mm , and
d = diameter of projected indentation, mm.
4. Significance and Use
4.1 Indentation hardness measurements have proven to be useful in rating coatings on rigid substrates for their resistance to
mechanical abuse, such as that produced by blows, gouging, and scratching. These measurements do not necessarily characterize
the resistance to mechanical abuse of coatings that are required to remain intact when deformed.
5. Test Specimens
5.1 The substrate for the coating shall be an acceptable plane rigid surface such as glass or metal.
5.2 The coating thickness on any one panel shall be uniform within 3 μm [0.1 mil]. Coatings to be compared shall be of equal
thickness within 5 μm [0.2 mil]. For maximum accuracy, the minimum permissible coating thickness shall be such that the depth
of indentation does not exceed three fourths of the coating thickness, to minimize the effect of the substrate.
5.3 At least three replicate specimens shall be tested for each coating to be evaluated.
5.4 Coatings should be applied in accordance with Practices D823 and their dry film thickness should be measured in
accordance with Test Methods D1005 or D7091.
5.5 From precoated sheets cut at least three specimens. Use only plane (flat) sheets and round the edges slightly. The coating
shall be free of oil and other foreign matter. Measure the film thickness as in 5.4.
METHOD A—KNOOP INDENTATION HARDNESS
6. Summary of Method
6.1 This method consists of applying a load to the surface of a coating by means of a pyramidal shaped diamond having
specified face angles, and converting the measurements of the resultant permanent impression to a hardness number.
7. Apparatus
7.1 Hardness Tester , consisting of a load applicator, a Knoop indenter, and a microscope fitted with a movable micrometer
stage. The apparatus shall mechanically bring the indenter into contact with the test surface with negligible impact, apply the
selected full load, maintain it for 18 6 0.5 s, and withdraw the indenter.
A hardness tester meeting the apparatus requirements for this method is the Tukon Microhardness Tester, available from the Wilson Instruments, Inc., Division of Instron,
100 Royall St., Canton, MA 02021.
D1474/D1474M − 13 (2018)
7.2 Knoop Indenter—The Knoop indenter is a pyramidal diamond with included longitudinal angles of 172° 30' and included
transverse angle of 130° 0'.
NOTE 1—The ratio of the long to the short diagonal of the impression is approximately 7:1; the ratio of the long diagonal to the depth of penetration
is approximately 30:1.
7.3 Microscope—The microscope shall have a filar micrometer eyepiece and sufficient objectives to permit the measurement of
the length of impression to within 61 %. The specimen shall be firmly supported on a movable micrometer stage attached to the
microscope.
8. Calibration
8.1 Adjust the illumination in the microscope to give maximum contrast when viewing an indentation.
8.2 By means of a calibrated scale, determine the factor for each microscope objective that converts the filar scale units of the
eyepiece to millimetres.
8.3 With a 25-g load on the indenter, determine the KHN of a calibrated standard (Note 2) with an assigned value not greater
than 50 KHN. If the obtained value is within 65 % of the assigned value, the instrument is considered to be in calibration.
NOTE 2—A suitable source of standard reference materials in this hardness range is available from the U.S. National Institute for Standards and
Technology. By agreement of the parties concerned, a stable specimen (such as an aged coating or a baked enamel applied to a flat substrate) could be
used to calibrate the participating hardness testers.
9. Procedure
9.1 Unless otherwise specified, make the hardness determinations at 23 6 2°C [73.5 6 3.50°F] and 50 6 5 % relative humidity
after equilibrating the specimens under these conditions for at least 24 hours.
9.2 Rigidly attach the specimen to the movable stage so that the surface to be measured is normal to the direction of indentation.
Mount the panel so that is cannot move with respect to the stage in any direction during the test.
9.3 Use the microscope to select an area of the test specimen that is free of surface irregularities and imperfections. Place this
area under the indenter by means of the movable micrometer stage.
NOTE 3—If good impressions cannot be obtained because of the roughness of the surface of the specimen, gently polish the surface with No. 400
carborundum and finish off with jewelers rouge before making the impression.
9.4 Present the apparatus to apply a load that permits the length of identification to be read accurately but does not cause the
depth of indentation to exceed three-quarters of the coating film thickness. Start the test cycle so that the indenter is mechanically
brought into contact with the mounted specimen under a load of 25 g and full load is applied, maintained for 18 6 0.5 seconds,
and removed. For maximum accuracy, ensure that the indenter has not penetrated the coating to a depth beyond three-fourths of
the coating thickness. This is necessary to eliminate any major substrate effect on the hardness values.
NOTE 4—For maximum accuracy, care must be taken that the indenter does not penetrate the coating to a depth beyond three fourths of the coating
thickness. This is necessary to eliminate any major substrate effect on the hardness m
...