ASTM D2210-21

Standard Test Method for Grain Crack and Extension of Leather by the Mullen Test

SIGNIFICANCE AND USE
4.1 The test method is designed to measure the force required to crack the grain of leather by steady hydraulic pressure on a diaphragm of definite diameter applied to the flesh side of the specimen to form a sphere. The cracking of the grain is a result of failure under elongation or stretch. The elongation or stretch of the leather can be measured at different loads or at the failure of the grain to determine if the stress leather will withstand under lasting conditions. Cuts, scratches, and other defects will cause considerable variation in the results by concentration of the applied force to the weak points. This test method is excellent for manufacturing control, specification acceptance, and service evaluation in the lasting property of leather. This test method may not apply when the conditions of the test employed differ widely from those specified in the test method.
SCOPE
1.1 This test method covers the determination of the resistance of leather to grain cracking and for measuring the extension of the leather. It is limited to light leathers such as shoe uppers, garment, gloves, and upholstery. This test method does not apply to wet blue or wet white.  
1.2 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.  
1.3 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: 30-Nov-2021
• ICS: 59.140.30 - Leather and furs
• Technical Committee: D31 - Leather
• Drafting Committee: D31.03 - Footwear

Relations

• Refers: ASTM D1610-01(2013) - Standard Practice for Conditioning Leather and Leather Products for Testing
• Effective Date: 01-May-2013
• Refers: ASTM D1813-13 - Standard Test Method for Measuring Thickness of Leather Test Specimens
• Effective Date: 01-May-2013
• Refers: ASTM D1813-00(2010) - Standard Test Method for Measuring Thickness of Leather Test Specimens
• Effective Date: 01-Oct-2010
• Refers: ASTM D1610-01(2007) - Standard Practice for Conditioning Leather and Leather Products for Testing
• Effective Date: 01-Apr-2007
• Refers: ASTM D1813-00(2005) - Standard Test Method for Measuring Thickness of Leather Test Specimens
• Effective Date: 01-Apr-2005
• Refers: ASTM D1610-00 - Standard Practice for Conditioning Leather and Leather Products for Testing
• Effective Date: 10-May-2001
• Refers: ASTM D1610-01 - Standard Practice for Conditioning Leather and Leather Products for Testing
• Effective Date: 10-May-2001
• Refers: ASTM D1813-00 - Standard Test Method for Measuring Thickness of Leather Test Specimens
• Effective Date: 10-May-2000

Overview

ASTM D2210-21: Standard Test Method for Grain Crack and Extension of Leather by the Mullen Test is an internationally recognized ASTM standard that specifies a reliable method for determining the resistance of light leather materials to grain cracking and measuring their extension properties. Using controlled hydraulic pressure via the Mullen Test, this method ensures manufacturers, quality control laboratories, and buyers can evaluate the durability and performance of leathers such as those used in shoe uppers, garments, gloves, and upholstery.

By applying pressure to the flesh side of a leather specimen, this standard assesses the force required to crack the grain and quantify leather extension. The data supports quality assurance, specification compliance, and ongoing manufacturing control.

Key Topics

• Hydraulic Pressure Testing: Explains the use of steady hydraulic pressure to stress leather specimens until grain cracking occurs.
• Measurement of Extension: Informs on measuring the stretch (extension) of leather at various loads or at grain failure to evaluate lasting stress resistance.
• Apparatus and Specimens: Describes equipment such as the Mullen tester, diaphragms, dial gauges, and specimen size selection.
• Result Interpretation: Highlights methods for calculating cracking pressure, stretch (as percentage), thickness, and pumping rate.
• Precision and Repeatability: Outlines criteria for consistent results within and between laboratories, enhancing test reliability.
• Exclusions and Limitations: Specifies that this method is for light leathers (not wet blue or wet white) and that defects like cuts or scratches will influence results.
• Safety Responsibilities: Reminds users to address all safety, health, and environmental concerns and adhere to regulatory requirements.

Applications

ASTM D2210-21 is widely applied in sectors that require assured leather quality and durability, including:

• Footwear and Accessories: Helps test shoe uppers and gloves for resistance to cracking and adequate extension, vital for wear and comfort.
• Upholstery: Supports assessment of upholstery leather's ability to withstand stretch and stress without surface cracking.
• Garment Leathers: Ensures garment leathers have appropriate extension and strength for lasting use.
• Manufacturing Quality Control: Enables producers to monitor production consistency, identify batch variations, and control input material quality.
• Specification and Contract Acceptance: Offers clear criteria for accepting or rejecting leather lots based on standardized testing.
• Research and Development: Aids in developing new leather materials or finishes with targeted performance characteristics.

Related Standards

When employing ASTM D2210-21, the following referenced ASTM standards frequently support or complement the test procedure:

• ASTM D1610: Practice for Conditioning Leather and Leather Products for Testing - essential for sample preparation and consistency.
• ASTM D1813: Test Method for Measuring Thickness of Leather Test Specimens - ensures accurate measurement of specimen thickness prior to testing.

Keywords: leather testing, grain crack, Mullen test, ASTM D2210, leather extension, hydraulic pressure, lasting property, quality control, light leathers, footwear, glove leather, upholstery leather.

Summary: ASTM D2210-21 is an authoritative standard that ensures precise evaluation of the grain crack resistance and extension properties of light leathers, facilitating quality assurance throughout the leather industry. Its adoption enhances confidence in leather performance for both manufacturers and consumers.

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: D2210 − 21
Standard Test Method for
Grain Crack and Extension of Leather by the Mullen Test
This standard is issued under the fixed designation D2210; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 3.1.1 extension—the amount of stretch of leather over the
diaphragm under pressure.
1.1 This test method covers the determination of the resis-
3.1.2 grain cracking—the appearance of cracks on the
tance of leather to grain cracking and for measuring the
surface of the leather as the leather is extended over a
extension of the leather. It is limited to light leathers such as
diaphragm under pressure to form a sphere.
shoe uppers, garment, gloves, and upholstery.This test method
does not apply to wet blue or wet white.
4. Significance and Use
1.2 The values stated in inch-pound units are to be regarded
4.1 The test method is designed to measure the force
as standard. The values given in parentheses are mathematical
required to crack the grain of leather by steady hydraulic
conversions to SI units that are provided for information only
pressure on a diaphragm of definite diameter applied to the
and are not considered standard.
fleshsideofthespecimentoformasphere.Thecrackingofthe
1.3 This standard does not purport to address all of the
grain is a result of failure under elongation or stretch. The
safety concerns, if any, associated with its use. It is the
elongationorstretchoftheleathercanbemeasuredatdifferent
responsibility of the user of this standard to establish appro-
loads or at the failure of the grain to determine if the stress
priate safety, health, and environmental practices and deter-
leatherwillwithstandunderlastingconditions.Cuts,scratches,
mine the applicability of regulatory limitations prior to use.
and other defects will cause considerable variation in the
1.4 This international standard was developed in accor-
resultsbyconcentrationoftheappliedforcetotheweakpoints.
dance with internationally recognized principles on standard-
This test method is excellent for manufacturing control, speci-
ization established in the Decision on Principles for the
fication acceptance, and service evaluation in the lasting
Development of International Standards, Guides and Recom-
property of leather. This test method may not apply when the
mendations issued by the World Trade Organization Technical
conditions of the test employed differ widely from those
Barriers to Trade (TBT) Committee.
specified in the test method.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards: 3
5.1 Testing Machine, asshowninFig.1.Themachineshall
D1610Practice for Conditioning Leather and Leather Prod-
be hand- or power-driven. The machine shall hold the speci-
ucts for Testing
men firmly, without slippage, between two annular, plane,
D1813Test Method for Measuring Thickness of Leather
unpolished (matte) surfaces that may have fine, spiral tool
Test Specimens
marks not over 0.010 in. (0.25 mm) in depth.
5.2 Upper Clamping Surface—The upper clamping surface
3. Terminology
(clamping ring) shall have a circular opening 1.240in. 6
3.1 Definitions:
0.010in. (31.50mm 6 0.25 mm) in diameter and shall be
connectedtotheclampingmechanismthroughaswiveljointto
ensure an even clamping pressure.
This test method is under the jurisdiction ofASTM Committee D31 on Leather
and is the direct responsibility of Subcommittee D31.03 on Footwear. This test
5.3 Lower Clamping Surface—The lower clamping surface
method was developed in cooperation with the American Leather Chemists Assn.
(diaphragm plate) shall be 0.219in. 6 0.003in. (5.56mm 6
(Standard Method E58–1965).
Current edition approved Dec. 1, 2021. Published January 2022. Originally
approved in 1963 as D2210–63T. Last previous edition approved in 2013 as
D2210–13. DOI: 10.1520/D2210-21. The sole source of supply of the apparatus known to the committee at this time
For referenced ASTM standards, visit the ASTM website, www.astm.org, or is B. F. Perkins, 939 Chicopee St., Chicopee, MA 01013-2797, [phone]. If
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM you are aware of alternative suppliers, please provide this information to ASTM
Standards volume information, refer to the standard’s Document Summary page on Headquarters.Your comments will receive careful consideration at a meeting of the
the ASTM website. responsible technical committee, which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2210 − 21
FIG. 1 Mullen Tester, Model A
0.08mm) thick and have an opening of 1.240in. 6 0.01 in. gauge shall be calibrated to read directly to the nearest 0.001
(31.50mm 6 0.52 mm) in diameter. The circular edges of the in. (0.03 mm). It shall be equipped with a flat anvil and a
openingsthatcomeincontactwiththespecimenandtherubber presser foot.
diaphragm shall be rounded to a radius of not over 0.025 in.
5.6 Bourdon Tube—The apparatus shall be equipped with a
(0.64 mm) to prevent any cutting action. During the test, the
Bourdon tube, maximum-reading-type, pressure gauge gradu-
circular edges of the openings in the two clamping plates shall
ated in pounds-force per square inch and accurate throughout
be substantially concentric with no overlapping of any point.
the entire range of its scale to within a value of 1% of its
5.4 Diaphragm, of rubber, 0.034in. 6 0.002 in. (0.86mm
maximum capacity. The capacity of the gauge shall be such
6 0.05 mm) thick, clamped under the lower clamping plate so
thattheindividualreadingswillbenotlessthan25%normore
that, before the diaphragm is stretched by pressure underneath
than 75% of the total capacity of the gauge.
it, the center of its upper surface is below the plane of the
5.7 Pressure Control—The machine shall be equipped with
clamping surface.
means of applying controlled increasing hydraulic pressure to
5.5 Dial Gauge, as shown in Fig. 2, to measure the
the underside of the diaphragm until the specimen cracks.This
extensionoftheleatherspecimenandmountedonthemachine
pressureshallbegeneratedbyapistonforcingaliquor(usually
through screw shaft or on side of clamps on platform. This
glycerin) into the pressure chamber of the apparatus. For
machines shown in Fig. 1 where the cracking pressure is the
only measurement, the pressure will be generated by pumping
liquid at a rate of 170mL⁄min 6 10 mL/min or by turning a
handwheel at approximately 30r⁄min. Record pumping rate or
cranking rate. For machines shown in Fig. 2 where cracking
pressure and extension are measured, the pressure will be
generated by pumping liquid at a rate of 15mL⁄min 6
2mL⁄minorbyturningahandwheelatapproximately3r⁄min.
NOTE 1—When equipment does not have a gauge to measure the flow
rate or uses a hand crank method, consult the equipment manufacturer or
operatingmanual.Resultsfromthedifferenttestermaynotbecomparable
because of the different flow rates.
5.8 Thickness Gauge—A dead-weight type of thickness
gauge as described in Test Method D1813.
6. Test Specimen
6.1 The specimen shall be a square of leather 3in. by 3 in.
(76mm by 76 mm) cut from the test unit of leather.
6.2 The specimen shall be free of mechanical damage and
FIG. 2 Mullen Tester with Dial Gauge surface defects.
D2210 − 21
7. Conditioning
Extension at Grain
Leathers Cracking Pressure, psi Crack, %
7.1 All specimens shall be conditioned in accordance with
Practice D1610. Shoe upper 26 13
Upholstery 17 14
A
Calfskin 16 22
8. Procedure
Glove 11 20
8.1 Determinethethicknessofthespecimenbytakingthree
A
measurements in the area to be cracked and determine the 3 oz ± 1 oz, 0.0468 in. ± 0.0156 in. (1.189 mm ± 0.396 mm).
average value.
10.1.2 Two Laboratories, Duplicate Specimens, Same
8.2 Place the flesh side of the specimen in contact with the
Skin—Results for the same group of light leathers listed in
rubber diaphragm of the testing machine.
10.1.1 submitted by each of two laboratories on duplicate
8.3 Clamp the specimen securely in the apparatus in such a
adjacent specimens in a skin taken from the official sampling
manner that the leather will not be damaged.
position should not be considered suspect unless the two
average results differ by more than 5%.
8.4 Rest the presser foot of the extension gauge on the flat
surface of the specimen and set the gauge at zero.
NOTE 2—The reproducibility reported in 10.1.2 is based on data
8.5 Apply pressure to the specimen until the specimen
obtained at two laboratories, and a different operator. The results show
close correlation between laboratories.
cracks.
NOTE 3—The results given in Section 10 are based on tests on 30 sides
8.6 At the moment the first crack appears in the specimen
of leather and do not apply to findings and cut parts.
stopthemachine,notetheappliedpressurefromthegauge,and
NOTE4—Theprecisiondataforbetweenskinsarenotincludedbecause
record the value as the cracking strength of the specimen.
the results were based on different skins from several production lots.The
variables in leather for between skins will give a higher variation of the
9. Report
results, but this factor should not affect the precision of the method.
9.1 The report shall include one or more of the following:
9.1.1 Cracking pressure to the nearest 5 psi (35 kPa) for 11. Keywords
each specimen or averaged and reported as the average of the
11.1 b
...

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: D2210 − 13 D2210 − 21
Standard Test Method for
Grain Crack and Extension of Leather by the Mullen Test
This standard is issued under the fixed designation D2210; 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
1.1 This test method covers the determination of the resistance of leather to grain cracking and for measuring the extension of the
leather. It is limited to light leathers such as shoe uppers, garment, gloves, and upholstery. This test method does not apply to wet
blue.blue or wet white.
1.2 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.
1.3 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 safety, health, and healthenvironmental 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.
2. Referenced Documents
2.1 ASTM Standards:
D1610 Practice for Conditioning Leather and Leather Products for Testing
D1813 Test Method for Measuring Thickness of Leather Test Specimens
3. Terminology
3.1 Definitions:
3.1.1 extension—the amount of stretch of leather over the diaphragm under pressure.
3.1.2 grain cracking—the appearance of cracks on the surface of the leather as the leather is extended over a diaphragm under
pressure to form a sphere.
4. Significance and Use
4.1 The test method is designed to measure the force required to crack the grain of leather by steady hydraulic pressure on a
This test method is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.03 on Footwear. This test method
was developed in cooperation with the American Leather Chemists Assn. (Standard Method E58 – 1965).
Current edition approved Nov. 1, 2013Dec. 1, 2021. Published November 2013January 2022. Originally approved in 1963 as D2210 – 63T. Last previous edition approved
in 20122013 as D2210 – 00D2210 – 13.(2012). DOI: 10.1520/D2210-13.10.1520/D2210-21.
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
D2210 − 21
diaphragm of definite diameter applied to the flesh side of the specimen to form a sphere. The cracking of the grain is a result of
failure under elongation or stretch. The elongation or stretch of the leather can be measured at different loads or at the failure of
the grain to determine if the stress leather will withstand under lasting conditions. Cuts, scratches, and other defects will cause
considerable variation in the results by concentration of the applied force to the weak points. This test method is excellent for
manufacturing control, specification acceptance, and service evaluation in the lasting property of leather. This test method may not
apply when the conditions of the test employed differ widely from those specified in the test method.
5. Apparatus
5.1 Testing Machine, as shown in Fig. 1. The machine shall be hand- or power-driven. The machine shall hold the specimen
firmly, without slippage, between two annular, plane, unpolished (matte) surfaces that may have fine, spiral tool marks not over
0.010 in. (0.25 mm) in depth.
5.2 Upper Clamping Surface—The upper clamping surface (clamping ring) shall have a circular opening 1.240 6 0.010 in. (31.50
1.240 in. 6 0.010 in. (31.50 mm 6 0.25 mm) in diameter and shall be connected to the clamping mechanism through a swivel joint
to ensure an even clamping pressure.
5.3 Lower Clamping Surface—The lower clamping surface (diaphragm plate) shall be 0.219 6 0.003 in. (5.56 6 0.08 mm)
0.219 in. 6 0.003 in. (5.56 mm 6 0.08 mm) thick and have an opening of 1.2401.240 in. 6 0.01 in. (31.50(31.50 mm 6 0.52 mm)
in diameter. The circular edges of the openings that come in contact with the specimen and the rubber diaphragm shall be rounded
to a radius of not over 0.025 in. (0.64 mm) to prevent any cutting action. During the test, the circular edges of the openings in the
two clamping plates shall be substantially concentric with no overlapping of any point.
5.4 Diaphragm, of rubber, 0.0340.034 in. 6 0.002 in. (0.86(0.86 mm 6 0.05 mm) thick, clamped under the lower clamping plate
so that, before the diaphragm is stretched by pressure underneath it, the center of its upper surface is below the plane of the
clamping surface.
5.5 Dial Gage,Gauge, as shown in Fig. 2, to measure the extension of the leather specimen and mounted on the machine through
screw shaft or on side of clamps on platform. This gagegauge shall be calibrated to read directly to the nearest 0.001 in. (0.03 mm).
It shall be equipped with a flat anvil and a presser foot.
FIG. 1 Mullen Tester, Model A
The sole source of supply of the apparatus known to the committee at this time is B. F. Perkins, 939 Chicopee St., Chicopee, MA 01013-2797, [phone]. If you
are aware of alternative suppliers, please provide this information to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible
technical committee, which you may attend.
D2210 − 21
FIG. 2 Mullen Tester with Dial GageGauge
5.6 Bourdon Tube—The apparatus shall be equipped with a Bourdon tube, maximum-reading-type, pressure gagegauge graduated
in pounds-force per square inch and accurate throughout the entire range of its scale to within a value of 1 % of its maximum
capacity. The capacity of the gagegauge shall be such that the individual readings will be not less than 25 % nor more than 75 %
of the total capacity of the gage.gauge.
5.7 Pressure Control—The machine shall be equipped with means of applying controlled increasing hydraulic pressure to the
underside of the diaphragm until the specimen cracks. This pressure shall be generated by a piston forcing a liquor (usually
glycerin) into the pressure chamber of the apparatus. For machines shown in Fig. 1 where the cracking pressure is the only
measurement, the pressure will be generated by pumping liquid at a rate of 170170 mL ⁄min 6 10 mL/min or by turning a
handwheel at approximately 3030 r r/min. ⁄min. Record pumping rate or cranking rate. For machines shown in Fig. 2 where
cracking pressure and extension are measured, the pressure will be generated by pumping liquid at a rate of 1515 mL ⁄min 6
22 mL mL/min ⁄min or by turning a handwheel at approximately 3 3 r r/min.⁄min.
NOTE 1—When equipment does not have a gauge to measure the flow rate or uses a hand crank method, consult the equipment manufacturer or operating
manual. Results from the different tester may not be comparable because of the different flow rates.
5.8 Thickness Gage—Gauge—A dead-weight type of thickness gagegauge as described in Test Method D1813.
6. Test Specimen
6.1 The specimen shall be a square of leather 33 in. by 3 in. (76(76 mm by 76 mm) cut from the test unit of leather.
6.2 The specimen shall be free of mechanical damage and surface defects.
7. Conditioning
7.1 All specimens shall be conditioned in accordance with Practice D1610.
8. Procedure
8.1 Determine the thickness of the specimen by taking three measurements in the area to be cracked and determine the average
value.
8.2 Place the flesh side of the specimen in contact with the rubber diaphragm of the testing machine.
D2210 − 21
8.3 Clamp the specimen securely in the apparatus in such a manner that the leather will not be damaged.
8.4 Rest the presser foot of the extension gagegauge on the flat surface of the specimen and set the gagegauge at zero.
8.5 Apply pressure to the specimen until the specimen cracks.
8.6 At the moment the first crack appears in the specimen stop the machine, note the applied pressure from the gage,gauge, and
record the value as the cracking strength of the specimen.
9. Report
9.1 The report shall include one or more of the following:
9.1.1 Cracking pressure to the nearest 5 psi (35 kPa) for each specimen or averaged and reported as the average of the test unit,
9.1.2 Extension of the leather to the nearest 0.001 in. (0.03 mm), 0.001 in. (0.03 mm), converted to percentage (see Annex A1)
and reported as percentage stretch, and
9.1.3 Thickness to the nearest 0.001 in. (0.03 mm) 0.001 in. (0.03 mm) reported for each specimen or averaged and reported as
the thickness of the sample.
9.1.4 Speed the liquid was pumped to build pressure to the nearest 10 % (see 5.7). Record revolutions per minute.
10. Precision and Bias
10.1 The following criteria may be used to judge the acceptability of the results if at least 15 units have been tested:
10.1.1 One Operator, Duplicate Specimens, Same Skin—Results by the same operator in duplicate adjacent specimens in a skin
taken from the official sampling position should not be considered suspect unless the coefficient of variation exceeds:
D2210 − 21
Extension at Grain
Leathers Cracking Pressure, psi Crack, %
Shoe upper
...