ASTM C473-19

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: C473 − 17 C473 − 19
Standard Test Methods for
Physical Testing of Gypsum Panel Products
This standard is issued under the fixed designation C473; 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.
1. Scope*
1.1 These test methods cover the physical testing of gypsum panel products.
1.2 The test methods appear in the following order:
Section
Flexural Strength (Method A) 7
Core, End and Edge Hardness (Method A) 8
Nail Pull Resistance (Method A) 9
Flexural Strength (Method B) 11
Core, End and Edge Hardness (Method B) 12
Nail Pull Resistance (Method B) 13
Humidified Deflection 14
End Squareness 15
Nominal Thickness 16
Recessed- or Tapered Edge Depth 17
Width 18
Length 19
Water Resistance of Core-Treated Water-Repellent
Gypsum Panel Products 20
Surface Water Resistance of Gypsum Panel Products
with Water-Repellent Surfaces 21
1.3 The values stated in inch-pound units are to be regarded as standard with the exception of weight of samples in SI gram
units. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not
considered standard.
1.4 The text of these test methods references notes and footnotes that provide explanatory material. These notes and footnotes,
excluding those in tables and figures, shall not be considered as requirements of these test methods.
1.5 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.
1.6 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:
C11 Terminology Relating to Gypsum and Related Building Materials and Systems
C1264 Specification for Sampling, Inspection, Rejection, Certification, Packaging, Marking, Shipping, Handling, and Storage of
Gypsum Panel Products
E4 Practices for Force Verification of Testing Machines
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
These test methods are under the jurisdiction of ASTM Committee C11 on Gypsum and Related Building Materials and Systems and are the direct responsibility of
Subcommittee C11.01 on Specifications and Test Methods for Gypsum Products.
Current edition approved Oct. 1, 2017Oct. 1, 2019. Published November 2017October 2019. Originally approved in 1961. Last previous edition approved in 20162017
as C473 – 16.C473 – 17. DOI: 10.1520/C0473-17.10.1520/C0473-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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
C473 − 19
2.2 Other Standards:
TAPPI T441 Water Absorptiveness of Sized (Non-Bibulous) Paper, Paperboard, and Corrugated Fiberboard (Cobb Test)
3. Terminology
3.1 Definitions used in these test methods are in accordance with Terminology C11.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 edge, n—the paper-bound edge, or long edge, as manufactured.
3.2.2 ends, n—the end perpendicular to the paper-bound edge or long edge.
3.2.3 Test Uncertainty Ratio (TUR),n—(tolerance of measure) / (precision of the standard measuring instrument)
4. Sampling
4.1 For use in these test methods, a sample shall consist of not less than 0.25 % of the number of gypsum panel products in
a shipment, but not less than three gypsum panel products. Test specimens shall be taken from the sample lot as indicated in each
method.samples obtained in accordance with Specification C1264.
5. Conditioning
5.1 Condition specimens to constant weight at a temperature of 85 6 15°F 15 °F (29.5 6 8.5°C) 8.5 °C) and relative humidity
of 50 6 2 % (Note 1). Test specimens individually after constant weight is reached and within 10 min upon removal from the
conditioning chamber.
NOTE 1—Laboratory test results indicated that conditioning temperatures may range from 70 to 100°F 100 °F (21 to 38°C) 38 °C) without significantly
affecting the results. However, relative humidity is critical. This is the reason for testing specimens within 10 min upon removal from the conditioning
chamber.
Method A—Constant Rate of Loading
INTRODUCTION
The following procedures are applicable to so-called “shot machines” that utilize lead or steel shot that applies a load to the
specimen at a constant stress rate or any other device that applies the load at a constant stress rate.
6. Apparatus—Method A
6.1 Testing Machine—Apply the test load at a uniform rate of 1 lbf/s (4.45 N/s) 610 %. Apply the load with a device
independent of manual control of the rate of loading during an individual sample test (see Fig. 1). The deformation of the specimen
controls the cross head speed.
7. Flexural Strength (Method A)
7.1 Summary of Test Method—Flexural properties of gypsum panel products are evaluated by supporting the specimen near the
ends and applying a transverse load midway between the supports.
FIG. 1 Apparatus Schematic for Core, End, and Edge Hardness Test
Available from Technical Association of the Pulp and Paper Industry (TAPPI), 15 Technology Parkway South, Norcross, GA 30092, http://www.tappi.org.
C473 − 19
7.2 Significance and Use—This test method covers a procedure for evaluating the ability of gypsum panel products to withstand
flexural stresses during handling or use of the material. This test method is used to determine compliance with gypsum panel
product specifications. The degree of correlation between this test and service performance has not been fully determined.
7.3 Apparatus—See 6.1.
7.3.1 Specimen Supports—All specimen bearing supports and load surfaces shall be true, shall engage the full width of the test
specimen, shall be of such strength they will not deform under the test load, and shall be rounded to a radius of 0.125 in. (3.2 mm).
The specimen supports shall be spaced 14 6 0.016 in. (356 6 0.41 mm) on centers measured at the points of surface contact with
the specimen. The supports shall be attached to a plate that shall be rigidly attached to the test apparatus. The supports shall be
parallel to each other and perpendicular to the long dimension of the test specimen. The bearing surface of the end supports shall
be on the same plane to ensure contact along the entire bearing surfaces. Supports shall be not less than 12 in. (305 mm) in length.
When a load is being applied, the loading bar shall be in contact with the full width of the specimen. The load-bearing surface shall
be parallel to the bearing surface of the specimen supports. The specimen and supports shall be located so that the vertical axis
through the center of the load-bearing surface passes through the specimen at one half of the specimen width and one half of the
distance between the supports.
7.4 Sampling—Sampling shall be in accordance with Section 4.
7.5 Test Specimens:
7.5.1 Cut four specimens, each 12 in. (305 mm) by approximately 16 in. (406 mm) from each gypsum panel product in the
sample, two having the 16-in. dimension parallel to the edge and two having the 16-in. dimension perpendicular to the edge. Cut
the specimens not less than 4 in. (102 mm) away from the ends and edges of the gypsum panel product except where the product
is 24-in. or less in width, where it is impossible to do so.
7.5.2 Condition specimens in accordance with Section 5.
7.6 Procedure:
7.6.1 Use the apparatus in 7.3, supporting each specimen centrally on the fixed parallel bearings, 14-in. (356 mm) on centers,
and apply the load on a similar bearing midway between the supports. Position perforated gypsum lath so the load is not applied
over perforations.
7.6.2 For specimens with the long dimension parallel to the edge, test one specimen from each gypsum panel product face up
and the other face down. For specimens with the long dimension perpendicular to the edge, test one specimen from each gypsum
panel product face up and the other face down.
7.6.3 For gypsum panel products with surfacing material, the load is determined at the time of transverse failure of the surfacing
material and core through the thickness of the specimen. The specimens shall not show a break in the bond between the surfacing
and the core before transverse failure of the gypsum panel product. If a single specimen fails, test two additional specimens from
the same sample, and, if either one of the two specimen fail, the sample has failed. For gypsum panel products without surfacing
material, the load is determined at the time of transverse failure through the thickness of the specimen.
7.7 Report—Calculate and report the average breaking load in pound-force or newtons for each test condition, rounded to the
nearest 1 lbf (N). The test conditions are: (1) parallel, face up; (2) parallel, face down; (3) perpendicular, face up; and, (4)
perpendicular, face down.
22 and Tables 1 and 2.
7.8 Precision and Bias—See Section
8. Core, End, and Edge Hardness (Method A)
8.1 Summary of Test Method—The core, end, and edge hardness of gypsum panel products is evaluated by determining the force
required to push a steel punch into the area of test.
8.2 Significance and Use—This test method covers a procedure for evaluating the ability of the gypsum panel product core,
ends, and edges to resist crushing during handling or use of the material. This test method is used to determine compliance with
gypsum panel product specifications. The degree of correlation between these test methods and service performance has not been
determined.
TABLE 1 Parallel Flexural Strength, Method B (lbf) 5 Labs / 81 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 49.4871 6.3911 11.9766 12.6641 33.5344 35.4593
B 85.2847 5.4871 16.3279 16.3279 45.7180 45.7180
C 35.6045 4.3757 6.3969 7.2970 17.9112 20.4316
A
The average of the laboratories’ calculated averages.
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TABLE 2 Perpendicular Flexural Strength, Method B (lbf) 7 Labs / 117 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 138.1732 3.8219 6.2402 6.8598 17.4725 19.2075
B 206.7995 7.4186 8.8020 10.9361 24.6457 30.6212
C 80.0015 1.9580 1.5868 2.4356 4.4431 6.8196
A
The average of the laboratories’ calculated averages.
8.3 Apparatus—See 6.1. Clamp or secure the specimen to the base of the test apparatus shown in Fig. 1 with the face of the
specimen perpendicular to the base of the test apparatus and parallel to the movement of the steel punch. Secure the steel punch
to the moving head of the test apparatus, positioned so that its center axis is parallel with the line of travel and so that the punch
is inserted into the core equidistant from the surfaces of the specimen. Use a steel punch 0.099 6 0.003 in. (2.515 6 0.076 mm)
in diameter and more than ⁄2 in. (12.7 mm) long with the bearing surface machined to a 90° angle in reference to the punch center
line (see Fig. 1 for test setup schematic).
8.4 Sampling—Sampling shall be in accordance with Section 4.
8.5 Test Specimens:
8.5.1 Specimens for Core Hardness—Using a table or band saw, cut one specimen from the center of each gypsum panel product
sample approximately 12 by not less than 3 in. (305 by 76 mm), with the 12-in. dimension perpendicular to the edges of the
products. The smaller, not less than 3 in., dimension will vary depending on the specific punch length and opening in the testing
machines. Place the sample in the tester, with the loading arm in a horizontal position and with the punch resting on the specimen.
Saw cuts along the 12-in. dimension shall be smooth and square with the smaller (not less than 3-in.) dimension, as well as with
the specimen.
8.5.2 Specimens for End Hardness—Cut specimens the same size and method as described in 8.5.1 from one mill-cut end of
the gypsum panel product, with the 12-in. (305 mm) dimension perpendicular to the edges and run tests only on the mill-cut end
of the specimens.
8.5.3 Specimens for Edge Hardness—Cut specimens the same size and method as described in 8.5.1 from the opposite edges
of each gypsum panel product, with the 12 in. (305 mm) dimension of the specimens parallel with the edges. For gypsum panel
1 1
products with surfacing material, cut a ⁄4 to ⁄2-in. (6 to 13 mm) strip of surfacing material from the edge of the test specimens
exposing the core for test. Remove as little of the core as possible when removing the surfacing material. Prepare the first test area
2 6 ⁄2 in. (51 6 13 mm) from one edge of the specimen, with the next two test areas approximately 4 in. (102 mm) apart.
8.5.4 Condition specimens in accordance with Section 5.
8.6 Procedure—Using the apparatus in 8.3, clamp or secure the specimen in a fixed vertical position on its 12 in. (305 mm)
dimension edge (see Fig. 1 for test setup schematic. If necessary, modify the flexural strength test equipment to conduct the core,
end, and edge hardness test). Place this test surface not less than 1 in. (25 mm) above the grip of the specimen holder. Conduct
three tests spaced approximately 4 in. (102 mm) apart on each specimen, with the first test area 2 6 ⁄2 in. (51 6 13 mm) from
one edge of the specimen. Position the steel punch over the test area and apply the load. Report as the core, end, or edge hardness
the load required to push the steel punch a distance of ⁄2 in. (13 mm) into the core of the specimen.
8.6.1 Procedure for Core Hardness—Test in three locations on either of the 12-in. (305 mm) saw cut edges of each specimen.
8.6.2 Procedure for End Hardness—Test in three locations on the 12-in. (305 mm) mill-cut end of each specimen.
8.6.3 Procedure for Edge Hardness—Test in three locations along each of the two 12-in. (305 mm) edges. For products with
surfacing material, test where the surfacing material has been removed.
8.7 Report—Report the core, end, and edge hardness individually as the average load in pounds-force or newtons rounded to
the nearest 1 lbf (N). Discard any single test value that varies from the average by more than 15 % and repeat the test on the same
sample to obtain a new value.
8.8 Precision and Bias—See Section 22 and Tables 3-5.
9. Nail Pull Resistance (Method A)
9.1 Summary of Test Method—The ability of gypsum panel products to resist nail pull-through is evaluated by determining the
load required to push a standard nail head through the product.
9.2 Significance and Use—This test method covers a procedure for evaluating the ability of gypsum panel products to resist nail
pull-through by determining the load required to force a standard nail head through the product. This test method is used to
determine compliance with gypsum panel product specifications. The degree of correlation between these test methods and service
performance has not been determined.
9.3 Apparatus—See 6.1. This apparatus shall be used with either of the specimen support plates in 9.3.1 or 9.3.2.
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TABLE 3 Core Hardness, Method B (lbf) 10 Labs / 71 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 22.4517 3.6610 1.0726 3.7896 3.0032 10.6110
B 24.4100 1.4329 1.2323 1.8218 3.4505 5.1010
C 25.4926 N/A 0.6774 0.6774 1.8968 1.8968
A
The average of the laboratories’ calculated averages.
TABLE 4 End Hardness, Method B (lbf) 10 Labs / 60 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 27.2263 N/A 0.6353 0.6353 1.7790 1.7790
B 24.5387 1.8854 1.0977 2.1351 3.0737 5.9784
A
The average of the laboratories’ calculated averages.
TABLE 5 Edge Hardness, Method B (lbf) 10 Labs / 120 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 60.3630 N/A 9.3561 9.3561 26.1970 26.1970
B 60.7652 5.5456 7.6803 9.2100 21.5047 25.7880
A
The average of the laboratories’ calculated averages.
9.3.1 Fig. 2 shows a schematic of a nail pull resistance apparatus adaptable to a typical flexural strength apparatus commonly
used in the gypsum industry. The specimen support plate shall have a 3-in. (76 mm) diameter hole in the center. The support plate
shall be not less than 6 by 6 in. (152 by 152 mm). It shall be attached to the apparatus as necessary to maintain the surface of the
plate perpendicular to the travel of the test nail. The support plate must also be located so that the vertical axis through the center
of the nail shank passes through the center of the hole in the support plate. The test nail shank shall be 0.099 6 0.003 in. (2.515
6 0.076 mm) in diameter and the nail head shall be 0.2506 0.005 in. (6.350 6 0.127 mm) in diameter. The nail shall be attached
at the head to the movable cross head of the test apparatus. This attachment shall not exceed the diameter of the nail head and shall
be placed directly over the head. It shall also be attached so that the vertical axis through the nail shank is parallel with the travel.
9.3.2 Fig. 3 shows a schematic of an alternate nail pull resistance apparatus adaptable to a typical flexural strength apparatus
commonly used in the gypsum industry. This apparatus mirrors all of the requirements of 9.3.1, except that the nail is not attached
at the head to the movable cross head of the test apparatus. The alternate apparatus utilizes a machined plunger with the nail head
and shank incorporated as an integral part of the plunger. The plunger fits into a bushing that keeps the nail aligned perpendicular
to the test specimen. Manufacture the plunger to slide freely through the bushing without the application of any load.
FIG. 2 Apparatus Schematic for Nail-Pull Resistance Test
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FIG. 3 (A) Typical Nail Pull Specimen Support Plate (View From Above)
FIG. 3 (B) Typical Nail Pull Specimen Support Plate (View From Side)
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NOTE 2—Other devices or means of allowing the plunger to move freely (such as collar bearings, and so forth) are also acceptable.
9.4 Sampling—Sampling shall be in accordance with Section 4.
9.5 Test Specimens:
9.5.1 Cut five specimens 6 by 6 in. (152 by 152 mm) from a strip cut across the width of each 48-in. (1220 mm) gypsum panel
product starting not less than 4 in. (102 mm) in from the edge. Cut a total of five specimens from more than one full width strip
from gypsum panel products less than 38 in. (965 mm) wide. Do not cut the specimen closer than 3 in. (76 mm) from the product
edges.
9.5.2 Drill a ⁄64-in. (2.778 mm) diameter pilot hole through the thickness of the gypsum panel product in the center of each test
specimen and perpendicular to the surface.
9.5.3 Condition specimens in accordance with Section 5.
9.6 Procedure—Using the apparatus in 9.3, center the specimen face up on the base plate and manually lower the test nail,
inserting the nail shank in the pilot hole, until the nail head is flush with the surface of the specimen. Apply the load until the
maximum load is achieved. Normally, this will occur as the nail head breaks through the gypsum panel product surface.
9.7 Report—Calculate the average maximum load in pounds-force or newtons, rounded to the nearest 1 lbf (N). Discard any
single test that varies from the average by more than 15 %. If more than 15 % of the test values are discarded, repeat the test.
9.8 Precision and Bias—See Section 22 and Table 6.
Method B—Constant Rate of Cross Head Speed
INTRODUCTION
The following procedures are applicable to so-called universal test machines. These instruments often use electronic load cells
and data acquisition equipment to gather information about the specimen being tested. The instruments generally in use move the
cross head at a constant speed, as opposed to having the deformation on the specimen control cross head speed, which would be
a true constant rate of strain instrument.
10. Apparatus
10.1 Testing Machine, of any type that is of sufficient capacity and that is capable of providing a rate of loading at a strain rate
of 1.0 in./min 6 5 s (25 mm/min 6 5 s). The load platform of the test equipment shall be of sufficient size to accept the specimen
holder and load applying apparatus. The testing machine shall be power operated and shall apply the load continuously and without
shock.
10.2 The test apparatus shall be verified according to Practices E4, the three sections titled “Basis of Verification,”
“Corrections,” and “Time Interval Between Verifications.”
10.3 Load-Indicating Equipment, capable of reading to 1-lbf (4.45 N) increments, shall be provided for the test apparatus. A
means shall be provided to indicate the maximum load attained during the test.
11. Flexural Strength (Method B)
11.1 Summary of Test Method—Flexural properties of gypsum panel products are evaluated by supporting the specimen near
the ends and applying a transverse load midway between the supports.
11.2 Significance and Use—This test method covers a procedure for evaluating the ability of gypsum panel products to
withstand flexural stresses during handling or use of the material. This test method is used to determine compliance with gypsum
panel product specifications. The degree of correlation between this test and service performance has not been fully determined.
11.3 Apparatus—See Section 10.
11.3.1 Specimen Supports—All bearing supports and load surfaces shall be true, shall engage the full width of the test specimen,
shall be of such strength they will not deform under the test load, and shall be rounded to a radius of 0.125 in. (3.2 mm). The
specimen supports shall be spaced 14 6 0.016 in. (356 6 0.41 mm) on centers measured at the points of surface contact with the
specimen. The supports shall be attached to a plate that shall be rigidly attached to the test apparatus. Test specimen supports shall
TABLE 6 Nail Pull Resistance, Method B (lbf) 10 Labs / 180 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 76.7023 3.9561 2.8870 4.7536 8.0837 13.3100
B 87.5646 4.1139 2.6243 4.7606 7.3479 13.3296
C 59.3105 5.1849 2.6658 5.7275 7.4642 16.0371
A
The average of the laboratories’ calculated averages.
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be parallel to each other and perpendicular to the long dimension of the test specimen. The bearing surface of the end supports
shall be on the same plane to ensure contact along the entire bearing surfaces. Supports shall be not less than 12 in. (305 mm) in
length. When a load is being applied, the loading bar shall be in contact with the full width of the specimen. The load-bearing
surface shall be parallel to the bearing surface of the specimen supports. The specimen and specimen supports shall be located so
that the vertical axis through the center of the load-bearing surface passes through the specimen at one half of the specimen width
and one half of the distance between the supports (see Fig. 4).
11.4 Sampling—Sampling shall be in accordance with Section 4.
11.5 Test Specimen:
11.5.1 Cut four specimens, each 12 in. (305 mm) by approximately 16 in. (406 mm) from each gypsum panel product in the
sample, two having the 16-in. dimension parallel to the edge and two having the 16-in. dimension perpendicular to the edge. Cut
the specimens not less than 4 in. (102 mm) away from the ends and edges of the gypsum panel product except where the product
is 24-in. or less in width, where it is impossible to do so.
11.5.2 Condition specimens in accordance with Section 5.
11.6 Procedure:
11.6.1 Use the apparatus in 11.3, supporting each specimen centrally on the fixed parallel supports, 14-in. (356 mm) on centers,
and apply the load on a similar bearing midway between the supports. Position perforated gypsum lath so the load is not applied
over perforations.
11.6.2 For specimens with the long dimension parallel to the edge, test one specimen from each gypsum panel product face up
and the other face down. For specimens with the long dimension perpendicular to the edge, test one specimen from each gypsum
panel product face up and the other face down.
11.6.3 For gypsum panel products with surfacing material, the load is determined at the time of transverse failure of the
surfacing material and core through the thickness of the specimen. The specimens shall not show a break in the bond between the
surfacing and the core before transverse failure of the gypsum panel product. If a single specimen fails, test two additional
specimens from the same sample, and, if either one of the two specimens fail, the sample has failed. For gypsum panel products
without surfacing material, the load is determined at the time of transverse failure through the thickness of the specimen.
11.7 Report—Calculate and report the average breaking load in pounds-force or newtons for each test condition, rounded to the
nearest 1 lbf (N). The test conditions are: (1) parallel, face up; (2) parallel, face down; (3) perpendicular, face up; and, (4)
perpendicular, face down.
11.8 Precision and Bias:
11.8.1 Precision—The 95 % repeatability limit of the Parallel, Face Up (Method B) test is the test result 64.796 lbf [21.33 N].
The 95 % reproducibility limit of the Parallel, Face Up (Method B) test is the test result 68.992 lbf [40.00 N].
FIG. 4 Testing Machine
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11.8.2 Precision—The 95 % repeatability limit of the Parallel, Face Down (Method B) test is the test result 65.087 lbf [22.63
N]. The 95 % reproducibility limit of the Parallel, Face Down (Method B) test is the test result 67.370 lbf [32.78 N].
11.8.3 Precision—The 95 % repeatability limit of the Across, Face Up (Method B) test is the test result 610.290 lbf [45.77 N].
The 95 % reproducibility limit of the Across, Face Up (Method B) test is the test result 613.368 lbf [59.46 N].
11.8.4 Precision—The 95 % repeatability limit of the Across, Face Down (Method B) test is the test result 611.704 lbf [52.06
N]. The 95 % reproducibility limit of the Across, Face Down (Method B) test is the test result 619.429 lbf [86.42 N].
11.8.5 Bias—No information can be presented on the bias of the procedure in these test methods for measuring the Flexural
Strength (Method B) because there is no material having an accepted reference value.
12. Core, End, and Edge Hardness (Method B)
12.1 Summary of Test Method—The core, end, and edge hardness of gypsum panel products is evaluated by determining the
force required to push a steel punch into the area of test.
12.2 Significance and Use—This test method covers a procedure for evaluating the ability of the gypsum panel product core,
ends, and edges to resist crushing during handling or use of the material. This test method is used to determine compliance with
gypsum panel product specifications. The degree of correlation between this test method and service performance has not been
fully determined.
12.3 Apparatus—See Section 10.
12.3.1 A means of securing the specimen to the base of the test apparatus shall be provided. The face of the specimen shall be
perpendicular to the base of the test apparatus and parallel to the movement of the steel punch. The steel punch shall be secured
to the moving head of the test apparatus. It shall be positioned so that its center axis is parallel with the line of travel. It also shall
be positioned so that the punch is inserted into the core equidistant from the surfaces of the specimen. The steel punch shall be
0.099 6 0.003 in. (2.515 6 0.076 mm) in diameter and more than ⁄2 in. (12.7 mm) long with the bearing surface machined to
a 90° angle in reference to the punch center line (see Figs. 5 and 6).
12.4 Sampling—Sampling shall be in accordance with Section 4.
12.5 Test Specimens:
12.5.1 Specimens for Core Hardness—Using a table or band saw, cut a specimen not less than 12 by 3 in. (305 by 76 mm) from
the center of each gypsum panel product. The 12-in. (305 mm) dimension shall be perpendicular to the edges of the gypsum panel
product. Cuts along the 12 in. (305 mm) dimension shall be smooth and perpendicular to the face of the specimen.
FIG. 5 Test Setup—Punch for Hardness and Nail Pull Resistance
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FIG. 6 Test Setup—Sample Holder for Hardness Test
12.5.2 Specimens for End Hardness—Cut a specimen not less than 12 by 3 in. (305 by 76 mm) from one mill-cut end of each
gypsum panel product. Cut the 12-in. (305 mm) dimension perpendicular to the edges of the gypsum panel product.
12.5.3 Specimens for Edge Hardness—Cut a specimen not less than 12 by 3 in. (305 by 76 mm) from each edge of each gypsum
panel product. Cut the 12-in. (305 mm) dimension parallel to the edge of the gypsum panel product. For gypsum panel products
1 1
with surfacing material, cut a ⁄4 to ⁄2-in. (6 to 13 mm) strip of surfacing material from the edge of the test specimens exposing
the core for test. Remove as little of the core as possible when removing the surfacing material. Prepare the first test area 2 6 ⁄2 in.
(51 6 13 mm) from one edge of the specimen, with the next two test areas spaced approximately 4 in. (102 mm) apart.
12.5.4 Condition specimens in accordance with Section 5.
12.6 Procedure—Using the apparatus in 12.3, clamp or secure the specimen in a fixed vertical position on its 12 in. (305 mm)
dimension edge. If necessary, modify the flexural strength test equipment to conduct the core, end, and edge hardness test. Place
this test surface not less than 1 in. (25 mm) above the grip of the specimen holder. After the specimen is in place, zero the load
indicator. Conduct three tests spaced approximately 4 in. (102 mm) apart on each specimen, with the first test area 2 6 ⁄2 in. (51 6
13 mm) from one edge of the specimen. Position the steel punch over the test area and apply the load. Report as the core, end,
or edge hardness the load required to push the steel punch a distance of ⁄2 in. (13 mm) into the core of the specimen.
12.6.1 Procedure for Core Hardness—Test in three locations on either of the 12-in. (305 mm) saw cut edges of each specimen.
12.6.2 Procedure for End Hardness—Test in three locations on the 12-in. (305 mm) mill-cut end of each specimen.
12.6.3 Procedure for Edge Hardness—Test in three locations along each of the two 12-in. (305 mm) edges. For products with
surfacing material, test where the surfacing material has been removed.
12.7 Report—Report the core, end, and edge hardness individually as the average load in pounds-force or newtons rounded to
the nearest 1 lbf (N). Discard any single test value that varies from the average by more than 15 % and repeat the test on the same
sample to obtain a new value.
12.8 Precision and Bias:
12.8.1 Precision—The 95 % repeatability limit of the End Hardness (Method B) test is the test result 68.103 lbf [36.04 N]. The
95 % reproducibility limit of the End Hardness (Method B) test is the test result 69.725 lbf [43.56 N].
12.8.2 Precision—The 95 % repeatability limit of the Core Hardness (Method B) test is the test result 64.231 lbf [18.82 N]. The
95 % reproducibility limit of the Core Hardness (Method B) test is the test result 69.668 lbf [43.01 N].
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12.8.3 Precision—The 95 % repeatability limit of the Edge Hardness (Method B) test is the test result 67.730 lbf [34.38 N].
The 95 % reproducibility limit of the Edge Hardness (Method B) test is the test result 623.031 lbf [102.45 N].
12.8.4 Bias—No information can be presented on the bias of the procedure in these test methods for measuring the End, Core,
and Edge Hardness because there is no material having an accepted reference value.
13. Nail Pull Resistance (Method B)
13.1 Summary of Test Method—The ability of gypsum panel products to resist nail pull-through is evaluated by determining the
load required to push a standard nail head through the product.
13.2 Significance and Use—This test method covers a procedure for evaluating the ability of gypsum panel products to resist
nail pull-through by determining the load required to force a standard nail head through the product. This test method is used to
determine compliance with gypsum panel product specifications. The degree of correlation between these test methods and service
performance has not been determined.
13.3 Apparatus—See Section 10. The apparatus shall be used with either of the specimen support plates in 13.3.1 or 13.3.2.
13.3.1 Specimen Support Plate, shall be true and have a 3-in. (76 mm) diameter hole in the center. The support plate shall be
not less than 6 by 6 in. (152 by 152 mm). It shall be attached to the apparatus as necessary to maintain the surface of the plate
perpendicular to the travel of the test nail. The support plate must also be located so that the vertical axis through the center of
the nail shank passes through the center of the hole in the support plate. The test nail shank shall be 0.099 6 0.003 in. (2.515 6
0.076 mm) in diameter and the nail head shall be 0.250 6 0.005 in. (6.350 6 0.127 mm) in diameter. The nail shall be attached
at the head to the movable cross head of the test apparatus. This attachment shall not exceed the diameter of the nail head and shall
be placed directly over the head. It shall also be attached so that the vertical axis through the nail shank is parallel with the travel.
See Figs. 5 and 7 for examples of the test setup configuration.
13.3.2 Fig. 3 shows a schematic of an alternate nail pull resistance apparatus adaptable to a typical flexural strength apparatus
commonly used in the gypsum industry. This apparatus mirrors all of the requirements of 13.3.1, except that the nail is not attached
at the head to the movable cross head of the test apparatus. The alternate apparatus utilizes a machined plunger with the nail head
and shank incorporated as an integral part of the plunger. The plunger fits into a bushing that keeps the nail aligned perpendicular
to the test specimen. Manufacture the plunger to slide freely through the bushing without the application of any load.
FIG. 7 Test Setup—Sample Holder for Nail Pull Resistance
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NOTE 3—Other devices or means of allowing the plunger to move freely (such as collar bearings, and so forth) are also acceptable.
13.4 Sampling—Sampling shall be in accordance with Section 4.
13.5 Test Specimens:
13.5.1 Cut five specimens 6 by 6 in. (152 by 152 mm) from a strip cut across the width of each 48-in. (1220 mm) gypsum panel
product starting not less than 4 in. (102 mm) in from the edge. Cut a total of five specimens from more than one full width strip
from gypsum panel products less than 38 in. (965 mm) wide. Do not cut the specimen closer than 3 in. (76 mm) from the product
edges.
13.5.2 Drill a ⁄64-in. (2.778 mm) diameter pilot hole through the thickness of the gypsum panel product in the center of each
test specimen and perpendicular to the surface.
13.5.3 Condition specimens in accordance with Section 5.
13.6 Procedure—Using the apparatus in 13.3, place the specimen on the specimen support plate so that the drilled hole is
aligned with the nail shank tip. After the specimen is in place, zero the load indicator. Insert the nail shank into the specimen hole
and apply the load until the maximum load is achieved. Normally, this will occur as the nail head breaks through the gypsum panel
product surface and is followed by a very significant decrease in load.
13.7 Report—Calculate the average maximum load in pounds-force or newtons, rounded to the nearest 1 lbf (N). Discard any
single test that varies from the average by more than 15 %. If more than 15 % of the test values are discarded, repeat the test.
13.8 Precision and Bias:
13.8.1 Precision—The 95 % repeatability limit of the Nail Pull (Method B) test is the test result 65.610 lbf [24.95 N]. The 95 %
reproducibility limit of the Nail Pull (Method B) test is the test result 68.961 lbf [39.86 N].
13.8.2 Bias—No information can be presented on the bias of the procedure in these test methods for measuring Nail Pull
because there is no material having an accepted reference value.
14. Humidified Deflection
14.1 Summary of Test Method—The humidified deflection of gypsum panel products is evaluated by supporting a specimen that
has been cut with the long dimension perpendicular to the machine direction, supported horizontally, and subjected to high
humidity for 48 h.
14.2 Significance and Use—This test method covers a procedure for evaluating the deflection of gypsum panel products when
horizontally suspended and subjected to high humidity. This test method is used to determine compliance with gypsum panel
product specifications. Since job factors other than high humidity influence the deflection of gypsum panel products, the degree
of correlation between this test method and service performance has not been determined.
14.3 Apparatus—A humidity cabinet of sufficient size to accommodate test specimens 12 by 24 in. (305 by 610 mm) capable
of maintaining an atmosphere of 90 6 3°F 3 °F (32 6 1.7°C) 1.7 °C) and 90 6 3 % relative humidity.
14.4 Sampling—Sampling shall be in accordance with Section 4.
14.5 Test Specimens:
14.5.1 Cut two specimens 12 by 24 in. (305 by 610 mm) from each gypsum panel product in the sample so the 12-in. dimension
is parallel to the edges. Cut specimens not less than 12-in. away from the ends and edges of gypsum panel products 48 in. (1220
mm) or more in width. Cut specimens from the center of gypsum panel products that are narrower than 48 in. (1220 mm) as noted
in Fig. 8.
14.5.2 Condition specimens in accordance with Section 5.
14.6 Test Procedure:
FIG. 8 Sample Selection Detail for Humidified Deflection Test
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14.6.1 Suspend each specimen face down on parallel and level bearing edges, having ⁄8-in. (3.2 mm) radii, 12 in. (305 mm)
long, and 23 in. (584 mm) apart in the humidity cabinet in an atmosphere of 90 6 3°F 3 °F (32 6 1.7°C) 1.7 °C) and 90 6 3 %
relative humidity for 48 h.
14.6.2 Measure and record the temperature and humidity at least one time each day during the duration of the test.
14.6.3 At the end of the 48 h conditioning period, measure the humidified deflection of each specimen, while suspended on the
bearing edges, as the distance between a straightedge placed on the top end edges of the gypsum panel product and the upper
surface of the product at its center. Take measurements to the nearest ⁄16 in. (1.6 mm).
14.7 Report—Report both the humidified deflection as the average of the specimens to the nearest ⁄8 in. (3 mm) and all
temperature and humidity measurements recorded.
14.8 Precision and Bias—See Section 22 and Table 7.
15. End Squareness
15.1 Summary of Test Method—The end squareness of gypsum panel products is evaluated by drawing a line perpendicular to
the edge of a full width specimen to its opposite edge and measuring the length of the side of the triangle formed.
15.2 Significance and Use—This test method covers a procedure for determining the end squareness of gypsum panel products.
This test method is used to determine compliance with gypsum panel product specifications. The degree of correlation between
this test method and service performance has not been determined.
15.3 Apparatus—A T-shaped or L-shaped square for drawing or testing right angles. The long edge of the square shall be not
less than 48 in.
15.4 Sampling—Sampling shall be in accordance with Section 4.
15.5 Test Specimens—Use full-size gypsum panel products with undamaged ends for test specimens.
15.6 Procedure—Place one edge of the square flush against the edge of the gypsum panel product with the apex of the square
at one corner of the product. Determine the distance b, to the nearest ⁄16 in. (1.6 mm) at the specified distance a. Distance is
measured from the apex of the square (see Fig. 9).
15.7 Report—Report the average of distance b to the nearest ⁄8 in. (3.2 mm).
15.8 Precision and Bias—The precision and bias of this test method has not been determined.
16. Thickness
16.1 Summary of Test Method—The thickness of gypsum panel products is evaluated by measuring the thickness of the
specimen with a micrometer.
16.2 Significance and Use—This test method covers a procedure for determining the average thickness of gypsum panel
products, and is used to determine compliance with gypsum panel product specifications. The degree of correlation between this
test method and service performance has not been determined.
16.3 Apparatus—A micrometer gage for determining the thickness measurement to 0.001 in. (0.025 mm). The micrometer shall
be a 1-in. (25.4 mm) hand micrometer with ⁄4-in. (6.35 mm) diameter anvils graduated to 0.01 in. (0.25 mm).
16.4 Sampling—Sampling shall be in accordance with Section 4.
16.5 Test Specimens:
16.5.1 Use full-size gypsum panel products for test specimens.
16.5.2 Mark the product to be tested, score on both sides, and break at 12 in. (305 mm) from each end, discarding the two ends
prior to testing. Retain the remaining part of each gypsum panel product as a test specimen.
16.6 Procedure—Mark measurement points at approximately equal points across the width at each end of the gypsum panel
product excluding the tapered, beveled, or recessed edges if applicable. Engage the micrometer firmly, but do not indent the
surfacing material of the gypsum panel product. Measure the thickness of the gypsum panel product with the micrometer not less
TABLE 7 Humidified Deflection (in.) 10 Labs / 176 Data Points
Standard
Repeatability Reproducibility
Deviation of Repeatability Reproducibility
A
Panel Average Standard Standard
the Sample Limit Limit
Deviation Deviation
Averages
χ¯ sχ¯ s s r R
r R
A 0.1566 0.0826 0.0397 0.0902 0.1112 0.2525
B 0.1143 0.0487 0.0644 0.0763 0.1802 0.2137
C 0.5952 0.3575 0.0829 0.3655 0.2323 1.0233
A
The average of the laboratories’ calculated averages.
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FIG. 9 End Squareness Determination
than ⁄2 in. (13 mm) from cut ends. Take a minimum of not less than seven readings at each end of the 54-in. (1370 mm) wide
gypsum panel product, six readings at each end of the 48-in. (1220 mm) wide gypsum panel product, five readings at each end
of the 32-in. (813 mm) wide gypsum panel product, four readings at each end of the 24-in. (610 mm) wide gypsum panel product,
or three readings at each end of the 16-in. (406 mm) wide gypsum panel product.
16.7 Report—Calculate the thickness of each specimen as the sum of the individual readings taken on each gypsum panel
product specimen then divided by the quantity of individual readings made on each specimen. Calculate and report the sample
thickness as the average measured thi
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