ASTM D1056-20

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: D1056 − 14 D1056 − 20
Standard Specification for
1,2
Flexible Cellular Materials—Sponge or Expanded Rubber
This standard is issued under the fixed designation D1056; 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 specification covers flexible cellular rubber products known as sponge rubber and expanded rubber, but does not apply
to latex foam rubber or ebonite cellular rubber. The base material for an open/closed cellular product may be made of synthetic,
natural, or reclaimed rubber, or a mixture, and may contain other polymers or chemicals, or both, which may be modified by
organic or inorganic additives. These elastomeric materials have properties similar to those of vulcanized rubber, namely (1) the
ability to be converted from a thermoplastic to a thermosetting state by crosslinking (vulcanization) or (2) the substantial recovery
of their original shapes when strained or elongated, or both.
1.2 Extruded or molded shapes of sizes too small for cutting standard test specimens are difficult to classify or test by these
methods and will usually require special testing procedures.
1.3 In case of conflict between the provisions of this general specification and those of detailed specifications or test methods for
a particular product, the latter shall take precedence. Reference to the test methods in this specification should specifically state
the particular test or tests desired.
1.4 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.
1.5 The following safety hazards caveat pertains only to the test methods portions of this specification: 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.
NOTE 1—ISO 6916-1 is similar to this specification.
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.
This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Materials - Plastics
and Elastomers.
This standard has been approved for use by agencies of the Department of Defense to replace Methods 12001, 12005, 12011, 12021, 12031, 12041, 12151, and 12411
of Federal Test Method Standard No. 601.
This standard has been approved for use by agencies of the Department of Defense to replace MIL-STD-670 and MIL-STD-C 3133, which were discontinued in 1986.
Current edition approved March 1, 2014Oct. 1, 2020. Published April 2014November 2020. Originally approved in 1949. Last previous edition approved in 20072014
as D1056 - 07.D1056 - 14. DOI: 10.1520/D1056-14.10.1520/D1056-20.
This version supersedes all prior versions of this specification.
*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
D1056 − 20
2. Referenced Documents
2.1 ASTM Standards:
D395 Test Methods for Rubber Property—Compression Set
D412 Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension
D471 Test Method for Rubber Property—Effect of Liquids
D573 Test Method for Rubber—Deterioration in an Air Oven
D575 Test Methods for Rubber Properties in Compression
D624 Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers
D832 Practice for Rubber Conditioning For Low Temperature Testing
D883 Terminology Relating to Plastics
D1171 Test Method for Rubber Deterioration—Surface Ozone Cracking Outdoors (Triangular Specimens)
D2632 Test Method for Rubber Property—Resilience by Vertical Rebound
D3182 Practice for Rubber—Materials, Equipment, and Procedures for Mixing Standard Compounds and Preparing Standard
Vulcanized Sheets
D3183 Practice for Rubber—Preparation of Pieces for Test Purposes from Products
D5132 Test Method for Horizontal Burning Rate of Polymeric Materials Used in Occupant Compartments of Motor Vehicles
E456 Terminology Relating to Quality and Statistics
E2935 Practice for Conducting Equivalence Tests for Comparing Testing Processes
2.2 ISO Standard:
ISO 6916-1 Flexible Cellular Polymeric Materials: Sponge and Expanded Cellular Rubber Products—Specification Part 1 Sheet
3. Terminology
3.1 Definitions—See Terms used in this standard are defined in accordance with Terminology D883, unless otherwise specified.
For terms relating to precision and bias and associated issues, the terms used in this standard are defined in accordance with
Terminology E456.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 cellular material—material, n—a generic term for materials containing many cells (either open or closed, or both) dispersed
throughout the mass.
3.2.2 closed cell—cell, n—a product whose cells are totally enclosed by its walls and hence not interconnecting with other cells.
3.2.3 expanded rubber—rubber, n—cellular rubber having closed cells made from a solid rubber compound.
3.2.4 flexible cellular material—material, n—a flexible cellular organic polymeric material cellular polymer that will not visibly
rupture within 60 s a specified time when a specimen 8 by 1 by 1 in. (200 by 25 by 25 mm) is bent around a 1-in. (25-mm) diameter
mandrel at a uniform rate of 1 lap/5 s in the form of a helix at a temperature between 65 and 85°F (18 and 29°C).25.4 mm (1.0
in.) mandrel 180 degrees within an agreed upon period of time and at a predetermined temperature.
3.2.5 open cell—cell, n—a product whose cells are not totally enclosed by its walls and open to the surface, either directly or by
interconnecting with other cells.
3.2.6 rubber—rubber, n—a material that is capable of recovering from large deformations quickly and forcibly, and can be, or
already is, modified to a state in which it is essentially insoluble (but can swell) in boiling solvent (such as benzene, methyl ethyl
ketone, and ethanol-toluene azeotrope).
3.2.6.1 Discussion—
A rubber in its modified state, free of diluents, retracts within 1 min to less than 1.5 times its original length after being stretched
at room temperature 68 to 80.6°F to twice its length and held for 1 min before release.
3.2.7 skin—skin, n—the textured outer surface on the material formed during manufacture by contact with molds, cover plate, air,
or other curing medium.
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D1056 − 20
3.2.7.1 Discussion—
Normally, this skin is formed by contact with the mold or cover plates during manufacture. Molded open-cell (sponge) parts
usually have a skin on all surfaces, except when cut to length from longer strips. Parts made by cutting from open-cell (sponge)
sheets usually have skin on two faces and open cells at the cut edges. Closed-cell (expanded) rubber sheets are frequently split from
thicker pieces and consequently do not have the skin faces. On some products it is desirable to add a solid rubber skin coating.
The use to which the cellular rubber product is to be put determines the thickness of added skin required. Products subject to
abrasion or open-cell (sponge) rubber that must withstand absorption of water or transmission of gases will ordinarily require an
applied skin coating. Closed-cell (expanded) rubber does not usually require an added skin for these reasons.
3.2.8 sponge rubber—rubber, n—cellular rubber consisting predominantly of open cells made from a solid rubber compound.
4. Classification (Types, Classes, Grades, and Suffix Letters) Grades)
4.1 Types—These specifications cover two types of cellular rubber designated by the prefix numbers 1 and 2.
4.1.1 Type 1—Open-cell rubber.
4.1.2 Type 2—Closed-cell rubber.
4.1.3 See Section 3 for definitions of open and closed cell.
4.2 Classes—Both types are divided into four classes designated by the letters A, B, C, and D added to the number prefix. Basic
requirements for classes are found in Tables 1 and 2.
4.2.1 Class A—Cellular rubber made from synthetic rubber, natural rubber, reclaimed rubber, or rubber-like materials, alone or in
combination, where specific resistance to the action of petroleum base oils is not required.
4.2.2 Class B—Cellular rubber made from synthetic rubber or rubber-like materials alone or in combination, having specific
requirements for oil resistance with low mass change.
4.2.3 Class C—Cellular rubber made from synthetic rubber or rubber-like materials alone or in combination, having specific
requirements for oil resistance with medium mass change.
4.2.4 Class D—Cellular rubber made from synthetic rubber or rubber-like materials alone or in combination having specific
requirements for extreme temperature resistance −103 to 347°F (−75 to 175°C); but specific resistance to the action of
petroleum-base oils is not required.
4.3 Grades—Each type and class has been divided into a number of different grades. Each grade is based on a specific range of
firmness as expressed by compression-deflection (see Sections 1918 to 2322). Grades are designated by digit,digit; the softer
grades being identified with the lower numbers and the higher grades being identified with the higher numbers.
4.3.1 Grade 0—For Types 1 and 2 cellular rubber, a compression-deflection range from 0 to 2 psi (0 to 13.8 kPa).
4.3.2 Grade 1—For Types 1 and 2 cellular rubber, a compression-deflection range from 2 to 5 psi (13.8 to 34.5 kPa).
4.3.3 Grade 2—For Types 1 and 2 cellular rubber, a compression-deflection range from 5 to 9 psi (34.5 to 62.1 kPa).
4.3.4 Grade 3—For Types 1 and 2 cellular rubber, a compression-deflection range from 9 to 13 psi (62.1 to 89.6 kPa).
4.3.5 Grade 4—For Types 1 and 2 cellular rubber, a compression-deflection range from 13 to 17 psi (89.6 to 117.2 kPa).
4.3.6 Grade 5—For Types 1 and 2 cellular rubber, a compression-deflection range from 17 to 25 psi (117.2 to 172.4 kPa).
NOTE 2—For conversion of types, classes, and grades to previous versions of Specification D1056, see Appendix X1.
D1056 − 20
5. Materials and Manufacture
5.1 Sponge Rubber—Sponge rubber is made by incorporating into the compound a blowing agent, such as sodium bicarbonate,
that gives off a gas which expands the mass during the vulcanization process. Sponge rubber is manufactured in sheet, strip,
molded, or special shapes. Unless otherwise specified, sheet and strip sponge rubber shall have a natural skin on both the top and
bottom surfaces. Fabric surface impressions are ordinarily not objectionable. The coarseness of the impressions shall be agreed
upon between the parties concerned.
5.2 Expanded Rubber—Closed-cell rubber is made by incorporating gas-forming ingredients in the rubber compound, or by
subjecting the compound to high-pressure gas, such as nitrogen. Expanded rubber is manufactured in sheet, strip, molded, tube,
cord, and profile shapes by molding or extruding. Unless otherwise specified, the presence of skin on the top or bottom surfaces
of sheet and strip expanded rubber shall be optional. Extruded shapes have skin on all surfaces except cut ends.
TABLE 1 Physical Requirements of Cellular Rubbers, Type 1, Open-Cell Sponge
Basic Requirements
Low-
Compression Deflection after Compression Set, 50 %
Oil-Aged 22 h at 158°F
Temperature
Oven Aging, Change from Original Deflection, max,%
Compression Deflection, 25 % (70°C), Change in Volume
Grade Number Flex, 5 h at
Deflection (Limits), psi (kPa) in ASTM Oil No. 3 (IRM
168 h at 158°F 22 h at 302°F 22 h at 158°F 22 h at 212°F
−67°F
903) (Limits),%
(70°C) (150°C) (70°C) (100°C)
(–55°C)
Class A, Non-oil-Resistant
Class A, Non-Oil-Resistant
A
1A0 less than 2 (13.8) ±20 . . 15 . .
1A1 2 to 5 (13.8 to 34.5) ±20 . . 15 . .
1A1 2 to 5 (13.8 to 34.5) ±20 . . 15 . .
1A2 5 to 9 (34.5 to 62.1) ±20 . . 15 . .
1A2 5 to 9 (34.5 to 62.1) ±20 . . 15 . .
1A3 9 to 13 (62.1 to 89.6) ±20 . . 15 . .
1A3 9 to 13 (62.1 to 89.6) ±20 . . 15 . .
1A4 13 to 17 (89.6 to 117.2) ±20 . . 15 . .
1A4 13 to 17 (89.6 to 117.2) ±20 . . 15 . .
1A5 17 to 25 (117.2 to 172.4) ±20 . . 15 . .
1A5 17 to 25 (117.2 to 172.4) ±20 . . 15 . .
B
Class B, Oil-Resistant, Low Mass Change
A
1B0 less than 2 (13.8) ±20 . −25 to + 10 40 . .
A
1B0 less than 2 (13.8) ±20 . −25 to + 10 40 . .
1B1 2 to 5 (13.8 to 34.5) ±20 . −25 to + 10 40 . .
1B1 2 to 5 (13.8 to 34.5) ±20 . −25 to + 10 40 . .
1B2 5 to 9 (34.5 to 62.1) ±20 . −25 to + 10 40 . .
1B2 5 to 9 (34.5 to 62.1) ±20 . −25 to + 10 40 . .
1B3 9 to 13 (62.1 to 89.6) ±20 . −25 to + 10 40 . .
1B3 9 to 13 (62.1 to 89.6) ±20 . −25 to + 10 40 . .
1B4 13 to 17 (89.6 to 117.2) ±20 . −25 to + 10 40 . .
1B4 13 to 17 (89.6 to 117.2) ±20 . −25 to + 10 40 . .
1B5 17 to 25 (117.2 to 172.4) ±20 . −25 to + 10 40 . .
1B5 17 to 25 (117.2 to 172.4) ±20 . −25 to + 10 40 . .
B
Class C, Oil-Resistant, Medium Mass Change
A
1C0 less than 2 (13.8) ±20 . + 10 to + 60 50 . .
A
1C0 less than 2 (13.8) ±20 . + 10 to + 60 50 . .
1C1 2 to 5 (13.8 to 34.5) ±20 . + 10 to + 60 50 . .
1C1 2 to 5 (13.8 to 34.5) ±20 . + 10 to + 60 50 . .
1C2 5 to 9 (34.5 to 62.1) ±20 . + 10 to + 60 50 . .
1C2 5 to 9 (34.5 to 62.1) ±20 . + 10 to + 60 50 . .
1C3 9 to 13 (62.1 to 89.6) ±20 . + 10 to + 60 50 . .
1C3 9 to 13 (62.1 to 89.6) ±20 . + 10 to + 60 50 . .
1C4 13 to 17 (89.6 to 117.2) ±20 . + 10 to + 60 50 . .
1C4 13 to 17 (89.6 to 117.2) ±20 . + 10 to + 60 50 . .
1C5 17 to 25 (117.2 to 172.4) ±20 . + 10 to + 60 50 . .
1C5 17 to 25 (117.2 to 172.4) ±20 . + 10 to + 60 50 . .
Class D, High-Temperature-Resistant
1D0 less than 2 (13.8) . ±5 . . 50 pass
1D0 less than 2 (13.8) . ±5 . . 50 pass
1D1 2 to 5 (13.8 to 34.5) . ±5 . . 50 pass
1D1 2 to 5 (13.8 to 34.5) . ±5 . . 50 pass
1D2 5 to 9 (34.5 to 62.1) . ±5 . . 30 pass
1D2 5 to 9 (34.5 to 62.1) . ±5 . . 30 pass
1D3 9 to 13 (62.1 to 89.6) . ±5 . . 30 pass
1D3 9 to 13 (62.1 to 89.6) . ±5 . . 30 pass
1D4 13 to 17 (89.6 to 117.2) . ±5 . . 30 pass
1D4 13 to 17 (89.6 to 117.2) . ±5 . . 30 pass
1D5 17 to 25 (117.2 to 172.4) . ±5 . . 30 pass
D1056 − 20
Requirements Added by Suffix Letters
Grade Number Compression Deflection, 25 % A4 B1 F M
Deflection (Limits), psi (kPa)
Compression Compression Set, Low-Temperature Flex Combustion
Deflection after 50 % Deflection, Characteristics,
Oven Aging, 22 h at 158°F max, 4 in./
Change from (70°C), max % min (100 mm/
Original, 22 h, min)
at 347°F
(175°C),
Limits, %
F1 F2 F3
5 h at −67°F 5 h at −103°F
5 h at −40°F (−40°C)
(−55°C) (−75°C)
Class A, Non-oil-Resistant
1A0 less than 2 (13.8) . . . . . . pass pass . . . pass
1A1 2 to 5 (13.8 to 34.5) . . . . . . pass pass . . . pass
1A2 5 to 9 (34.5 to 62.1) . . . . . . pass pass . . . pass
1A3 9 to 13 (62.1 to 89.6) . . . . . . pass pass . . . pass
1A4 13 to 17 (89.6 to 117.2) . . . . . . pass pass . . . [pass
1A5 17 to 25 (117.2 to 172.4) . . . . . . pass pass . . . pass
B
Class B, Oil-Resistant, Low Mass Change
1B0 less than 2 (13.8) . . . . . . pass . . . . . . pass
1B1 2 to 5 (13.8 to 34.5) . . . . . . pass . . . . . . pass
1B2 5 to 9 (34.5 to 62.1) . . . . . . pass . . . . . . pass
1B3 9 to 13 (62.1 to 89.6) . . . . . . pass . . . . . . pass
1B4 13 to 17 (89.6 to 117.2) . . . . . . pass . . . . . . pass
1B5 17 to 25 (117.2 to 172.4) . . . . . . pass . . . . . . pass
B
Class C, Oil-Resistant, Medium Mass Change
1C0 less than 2 (13.8) . . . 25 pass . . . . . . pass
1C1 2 to 5 (13.8 to 34.5) . . . 25 pass . . . . . . pass
1C2 5 to 9 (34.5 to 62.1) . . . 25 pass . . . . . . pass
1C3 9 to 13 (62.1 to 89.6) . . . 25 pass . . . . . . pass
1C4 13 to 17 (89.6 to 117.2) . . . 25 pass . . . . . . pass
1C5 17 to 25 (117.2 to 172.4) . . . 25 pass . . . . . . pass
D1056 − 20
Class D, High-Temperature-Resistant
A
1D0 less than 2 (13.8) ±25 . . . pass . . . pass pass
1D1 2 to 5 (13.8 to 34.5) ±25 . . . pass . . . pass pass
1D2 5 to 9 (34.5 to 62.1) ±25 . . . pass . . . pass pass
1D3 9 to 13 (62.1 to 89.6) ±25 . . . pass . . . pass pass
1D4 13 to 17 (89.6 to 117.2) ±25 . . . pass . . . pass pass
1D5 17 to 25 (117.2 to 172.4) ±25 . . . pass . . . pass pass
A
If this grade after aging still falls within the compression-deflection requirement of <2 psi (13.8 kPa), it shall be considered acceptable even though the change from the
original is greater than ±20 %.
B
Terminology was changed in 1997 from low swell to low mass change to better reflect the data obtained.
TABLE 2 Physical Requirements of Cellular Rubbers, Type 2, Closed-Cell Expanded
Basic Requirements
Oven-Aged, Change
from Original Compression
Water Absorption, max, Fluid Immersion, 7 Days at
Compression Set, 50 % Low-
B
Compression Change in Weight, % 73.4°F (23°C), max %
Deflection Values Constant Temperature
Grade Deflection, 25 %
(Limits), % Deflection, 22 Flex, 5 h at
Number Deflection (Limits), psi
168 h at 22 h at Density over Density of 10 Density over Density of h at 212°F −67°F
(kPa)
3 3 3 3
158°F 302°F 10 lb/ft (160 lb/ft (160 10 lb/ft (160 10 lb/ft (160 (100°C), max (−55°C)
3 3 3 3
(70°C) (150°C) kg/m ) kg/m ) or kg/m ) kg/m ) or %
less less
Class A, Nonfuel-Resistant
A
2A0 less than 2 (13.8) ±30 . 5 10 . . . .
2A1 2 to 5 (13.8 to 34.5) ±30 . 5 10 . . . .
2A2 5 to 9 (34.5 to 62.1) ±30 . 5 10 . . . .
2A3 9 to 13 (62.1 to 89.6) ±30 . 5 10 . . . .
2A4 13 to 17 (89.6 to ±30 . 5 10 . . . .
117.2)
2A5 17 to 25 (117.2 to ±30 . 5 10 . . . .
172.4)
C
Class B, Fuel-Resistant, Low Mass Change
A
2B0 less than 2 (13.8) ±30 . 5 10 50 100 . .
2B1 2 to 5 (13.8 to 34.5) ±30 . 5 10 50 100 . .
2B2 5 to 9 (34.5 to 62.1) ±30 . 5 10 50 100 . .
2B3 9 to 13 (62.1 to 89.6) ±30 . 5 10 50 100 . .
2B4 13 to 17 (89.6 to ±30 . 5 10 50 100 . .
117.2)
2B5 17 to 25 (117.2 to ±30 . 5 10 50 100 . .
172.4)
C
Class C, Fuel-Resistant, Medium Mass Change
A
2C0 less than 2 (13.8) ±30 . 5 10 150 250 . .
2C1 2 to 5 (13.8 to 34.5) ±30 . 5 10 150 250 . .
2C2 5 to 9 (34.5 to 62.1) ±30 . 5 10 150 250 . .
2C3 9 to 13 (62.1 to 89.6) ±30 . 5 10 150 250 . .
2C4 13 to 17 (89.6 to ±30 . 5 10 150 250 . .
117.2)
2C5 17 to 25 (117.2 to ±30 . 5 10 150 250 . .
172.4)
Class D, High-Temperature-Resistant
2D0 less than 2 (13.8) . ±5 5 10 . . 80 pass
2D1 2 to 5 (13.8 to 34.5) . ±5 5 10 . . 80 pass
2D2 5 to 9 (34.5 to 62.1) . ±5 5 10 . . 60 pass
2D3 9 to 13 (62.1 to 89.6) . ±5 5 10 . . 60 pass
2D4 13 to 17 (89.6 to . ±5 5 10 . . 60 pass
117.2)
2D5 17 to 25 (117.2 to . ±5 5 10 . . 60 pass
172.4)
Requirements Added By Suffix Letters
A B F M
Compression Deflection After Oven Aging, Compression Set, 50 % Low Temperature Flex, 5 h at
Compression Deflection Change from Original Limits, % Deflection, max % Temperature Combustion
Grade
25 % Deflection (Limits), 22 h at 22 h at 22 h at 22 h at 22 h at 22 h at Characteristics, 4
Number –40°F –67°F –103°F
psi (kPa) 212°F 257°F 302°F 350°F 73.4°F 73.4°F in./min max (100
(–40°C) (–55°C) (–75°C)
(100°C) (125°C) (150°C) (175°C) (23°C ) (23°C) mm/min max)
A1 A2 A3 A4 B2 B3 F1 F2 F3
2A0 less than 2 (13.8) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2A1 2 to 5 (13.8 to 34.5) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2A2 5 to 9 (34.5 to 62.1) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2A3 9 to 13 (62.1 to 89.6) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2A4 13 to 17 (89.6 to 117.2) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2A5 17 to 25 (117.2 to 172.4) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2B0 less than 2 (13.8) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
D1056 − 20
2B1 2 to 5 (13.8 to 34.5) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2B2 5 to 9 (34.5 to 62.1) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2B3 9 to 13 (62.1 to 89.6) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2B4 13 to 17 (89.6 to 117.2) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2B5 17 to 25 (117.2 to 172.4) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2C0 less than 2 (13.8) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2C1 2 to 5 (13.8 to 34.5) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2C2 5 to 9 (34.5 to 62.1) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2C3 9 to 13 (62.1 to 89.6) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2C4 13 to 17 (89.6 to 117.2) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
2C5 17 to 25 (117.2 to 172.4) ±30 % ±30 % ±30 % ±30 % 25 % 35 % pass pass pass pass
D D D D D
2D0 less than 2 (13.8) NA NA NA ±30 % 25 % 35 % NA NA pass pass
D D D D D
2D1 2 to 5 (13.8 to 34.5) NA NA NA ±30 % 25 % 35 % NA NA pass pass
D D D D D
2D2 5 to 9 (34.5 to 62.1) NA NA NA ±30 % 25 % 35 % NA NA pass pass
D D D D D
2D3 9 to 13 (62.1 to 89.6) NA NA NA ±30 % 25 % 35 % NA NA pass pass
D D D D D
2D4 13 to 17 (89.6 to 117.2) NA NA NA ±30 % 25 % 35 % NA NA pass pass
D D D D D
2D5 17 to 25 (117.2 to 172.4) NA NA NA ±30 % 25 % 35 % NA NA pass pass
A
If this grade after aging still falls within the compression-deflection requirement of <2 psi (13.8 kPa), it shall be considered acceptable even though the change from the
original is greater than ±30 %.
B
This test (see Sections 27 – 34 ) of weight change in Reference Fuel B is used in place of the usual oil-resistance test of volume change of No. 3 oil for the following
reason: Oil or solvent immersion of flexible closed cellular materials usually causes loss of gas, by diffusion through the softened cell walls, that results in some shrinkage
of the test sample. This shrinkage counteracts the swell that would normally occur, therefore invalidating test data based on volume change. Reference Fuel B is used
because it produces a wider and more consistent differentiation among the A, B, and C classes than does the No. 3 oil.
C
Standard oil resistance test methods give inconsistent results on closed cellular materials. This test gives a general indication of oil resistance, but more reliable
information should be obtained by testing in actual or simulated service conditions.
3 3
The values of 150 % maximum Class C and 50 % maximum Class B apply to cellular materials having densities of more than 10 lb/ft (160 kg/m ). For cellular materials
with densities of 10 lb/ft or less, the values of maximum mass change allowed are 250 % for Class C and 100 % for Class B.
Terminology was changed in 1997 from low swell to low mass change to better reflect the data obtained.
D
NA = Not applicable. Already covered as a basic requirement in Table 2.
6. Physical Properties
6.1 The various grades of cellular rubber shall conform to the basic requirements as to physical properties in Table 1 and Table
2 together with any additional requirements indicated by suffix letters in. Any additional requirements desired by the end user shall
be indicated by adding suffix letters from Table 3 to the grade designations as described in Section 4 and Table 3.
TABLE 3 ASTM Test Methods
NOTE 1—See Table 1 or Table 2 for established requirements for open or closed cell forms respectively.
NOTE 2—Test Methods D412 was intended for testing dense rubber samples. It requires a sample thickness of between 0.060 and 0.120 in. (1.5 and
3 mm). This thickness is difficult to achieve on some foam products. In addition, foam samples, particularly low-compression deflection products can be
difficult to measure gauge. There is also no mention of allowance for skin or no skin samples. For these reasons, tensile samples tested in accordance
with Specification D1056 are allowed to be up to 0.250 in. (6.35 mm) thick and should be tested with or without skin as used in the application.
Basic Requirements and Suffix
Number Requirement or Suffix Basic Requirements Suffix Number 1 Suffix Number 2 Suffix Number 3 Suffix Number 4
Letter
Compression deflection Specification D1056, Sec-
tions 17 – 23
Compression deflection Specification D1056, Sec-
tions 16 – 22
Heat resistance Specification D1056, Sec-
tions 16 – 23, change in
compression deflection
after aging 7 days at
158°F (70°C)
Heat resistance Specification D1056, Sec-
tions 15 – 22, change in
compression deflection
after aging 7 days at
158°F (70°C)
Fluid resistance (1B and 1C Specification D1056, Sec-
rubber only) tions 24 – 34,
Fluid resistance (1B and 1C Specification D1056, Sec-
rubber only) tions 23 – 34,
22 h
at 158°F (70°C)
A
Fluid resistance (2B and 2C) Specification D1056 Sec-
tions 27 – 34, 7 days at
73.4°F (23°C)
D1056 − 20
TABLE 3 Continued
Basic Requirements and Suffix
Number Requirement or Suffix Basic Requirements Suffix Number 1 Suffix Number 2 Suffix Number 3 Suffix Number 4
Letter
Compression set (1A, 1B, and Specification D1056, Sec-
1C) tions 50 – 56, 22 h at
158°F (70°C), 50 %
deflection, 30-min recov-
ery at 73.4°F (23°C)
Compression set (1D and 2D Specification D1056, Sec-
rubber only) tions 50 – 56, 22 h at
212°F (100°C), 50 %
deflection, 30-min recov-
ery at 73.4°F (23°C)
Water absorption (2A, 2B, 2C, Specification D1056, Sec-
and 2D) tions 43 – 49
Optional Requirements
Suffix A, heat resistance Specification D1056, Sec- Specification D1056, Sec- Specification D1056, Sec- Specification D1056, Sec-
tions 16 – 23, tions 16 – 23, tions 16 – 23, tions 16 – 23,
change in compression change in compression change in compression change in compression
deflection after aging deflection after aging deflection after aging deflection after aging
22 h at 212°F (100°C) 22 h at 257°F (125°C) 22 h at 302°F (150°C) 22 h at 350°F (175°C)
Suffix A, heat resistance Specification D1056, Sec- Specification D1056, Sec- Specification D1056, Sec- Specification D1056, Sec-
tions 15 – 22, tions 15 – 22, tions 15 – 22, tions 15 – 22,
change in compression change in compression change in compression change in compression
deflection after aging deflection after aging deflection after aging deflection after aging
22 h at 212°F (100°C), 22 h at 257°F (125°C), 22 h at 302°F (150°C), 22 h at 350°F (175°C),
Limits ±30 % Limits ±30 % Limits ±30 % Limits ±30 %
Suffix B, compression set (B1 for Specification D1056, Sec- Specification D1056, Sec- Specification D1056, Sec-
1A, 1B, and 1C only) (B2 & B3 tions 50 – 68, 22 h at tions 50 – 68, 22 h at tions 50 – 68, 22 h at
for 2A, 2B, 2C, 2D only) 158°F (70°C), 50 % 73.4°F (23°C), 50 % 73.4°F (23°C), 50 %
deflection, 30-min recov- deflection, 24-h recovery deflection, 24-h recovery
ery at 73.4°F (23°C), at 73.4°F (23°C), 25 % at 73.4°F (23°C) 35 %,
25 % max max max
Suffix C, ozone or weather resis- Test Method D1171, Test Method D1171, Test Method D1171,
B
tance ozone chamber outdoor exposure, ozone exposure (ozone
exposure, Method A: Exposure chamber or outdoor), Test
Method A. Exposure Rating Method B: Quality Reten-
rating (Exposure Method tion Rating
A or B)
C
Suffix D, load deflection
C
Suffix E, fluid resistance
Suffix F, Low-temperature resis- Specification D1056, Sec- Specification D1056, Sec- Specification D1056, Sec-
tance tions 57 – 61, 5 h at tions 57 – 61, 5 h at tions 57 – 61, 5 h at
−40°F (−40°C) −67°F (−55°C) −103°F (−75°C)
B
Suffix G, tear resistance Test Method D624 Die C
C
Suffix J, abrasion resistance
C
Suffix K, adhesion capability Rubber compound must
be suitable for, and able
to accept adhesive bond-
ing.
C
Suffix L, water absorption
D
Suffix M, combustion characteristics Test Method D5132 4 in./
min, max (100 mm/min,
max)
C
Suffix N, impact resistance
C
Suffix P, staining resistance
B
Suffix R, resilience Test Method D2632
(Shore Rebound)
B
Suffix T, Tensile/Elongation Test Method D412 except
specimen thickness, See
Note 2
B
Suffix T, Tensile/Elongation Test Method D412 except
specimen thickness, see
Note 2
B
Suffix W, density Specification D1056 Sec-
tions 62 – 68
C
Suffix Z, special requirements
A 3 3
See Table 2 for materials having densities of 10 lb/ft (160 kg/m ) or less.
B
Ratings to be arranged between the purchaser and the supplier.
C
Test method and values to be arranged between the purchaser and the supplier.
D
Specimen to be at application thickness.
D1056 − 20
TABLE 4 Tolerances on Dimensions of Cellular Rubber Products for General Applications
Thickness Length and Width
Form
Tolerance, ±, in. Tolerance, ±, in.
Dimension, in. (mm) Dimension, in. (mm)
(mm) (mm)
Sponge Rubber
Sheet and strip 0.125 (3.2) and under 0.016 (0.4) 6 (152) and under 0.063 (1.6)
Over 0.125 (3.2) to 0.50 (12.7), incl 0.032 (0.8) Over 6 (152) to 18 (457), incl 0.125 (3.2)
Over 12.7 (0.50) 0.047 (1.2) Over 18 (457) 0.5 %
Molded or special shapes 0.250 (6.4) and under 0.032 (0.8) 0.250 (6.4) and under 0.032 (0.8)
Over 0.250 (6.4) to 3 (76.2), incl 0.063 (1.6) Over 0.250 (6.4) to 3 (76), incl 0.063 (1.6)
Over 3 (76) to 18 (457), incl 0.125 (3.2)
Over 18 (457) 0.5 %
Expanded Rubber
Sheet and strip 0.125 (3.2) and under 0.063 (1.6) 6 (152) and under 0.250 (6.4)
0.125 (3.2) to 0.50 (12.7), incl 0.063 (1.6) 6 (152) and under 0.250 (6.4)
Over 0.50 (12.7) 0.094 (2.4) Over 6 (152) to 305 (12), incl 0.375 (9.6)
Over 12 (305) 3 %
Molded or special shapes 0.125 (3.2) to 0.50 (12.7), incl 0.063 (1.6) 6 (152) and under 0.250 (6.4)
Over 0.50 (12.7) to 1.50 (38.1), incl 0.094 (2.4) Over 6 (152) to 12 (305), incl 0.375 (9.6)
Over 1.50 (38.1) to 3 (76.2), incl 0.125 (3.2) Over 12 (305) 3 %
D1056 − 20
7. Tolerances on Dimensions
7.1 Tolerances on dimensions of cellular rubber products shall be as specified in Table 4.
8. Color
8.1 Unless otherwise specified, the color of cellular rubber shall be black.
9. Workmanship, Finish, and Appearance
9.1 Cellular rubber furnished under this specification shall be manufactured from synthetic rubber, natural rubber, or rubber-like
materials together with added compounding ingredients of such nature and quality that the finished product complies with the
specification requirements. In permitting choice in use of those materials by the producer, it is not intended to imply that the
different rubber materials are equivalent in respect to all physical properties. Any special characteristics other than those prescribed
in this specification that may be desired for specific applications shall be specified in the product specifications, as they may
influence the choice of the type of rubber material or other ingredients used. All materials and workmanship shall be in accordance
with good commercial practice, and the resulting cellular rubber shall be free from defects affecting serviceability.
10. Test Methods
10.1 Unless specifically stated otherwise, all tests shall be made in accordance with the methods specified in Sections 1413 – 68
and Table 3.
11. Sampling
11.1 When possible, the completed manufactured product shall be used for the tests specified. Representative samples of the lot
being examined shall be selected at random as required.
11.2 When it is necessary or advisable to obtain test specimens from the article, as in those cases where the entire sample is not
required or adaptable for testing, the method of cutting and the exact position from which specimens are to be taken shall be
specified. The apparent density and the state of cure may vary in different parts of the finished product, especially if the article is
of complicated shape or of varying thickness, and these factors affect the physical properties of the specimens. Also, the apparent
density is affected by the number of cut surfaces as opposed to the number of skin-covered surfaces on the test specimen.
11.3 When the finished product does not lend itself to testing or to the taking of test specimens because of complicated shape,
small size, metal or fabric inserts, solid covers, adhesion to metal, or other reasons, standard test slabs shall be prepared. When
differences due to the difficulty in obtaining suitable test specimens from the finished part arise, the manufacturer and the purchaser
may agree on acceptable deviations. This can be done by comparing results of standard test specimens and those obtained on actual
parts.
12. Inspection and Rejection
12.1 All tests and inspection shall be made at the place of manufacture prior to shipment, unless otherwise specified. The
manufacturer shall afford the inspector all reasonable facilities for tests and inspection.
12.2 The purchaser may make the tests and inspection to govern acceptance or rejection of the material at his own laboratory or
elsewhere. Such tests and inspection shall be made not later than 15 days after receipt of the material.
12.3 All samples for testing, provided as specified in Section 11, shall be visually inspected to determine compliance with the
material, workmanship, and color requirements.
12.4 Any material that fails in one or more of the test requirements may be retested. For this purpose, two additional tests shall
be made for the requirement in which failure occurred. Failure of either of the retests shall be cause for final rejection.
12.5 Rejected material shall be disposed of as directed by the manufacturer.
D1056 − 20
13. Packaging and Package Marking
13.1 The material shall be properly and adequately packaged. Each package or container shall be legibly marked with the name
of the material, name or trademark of the manufacturer, and any required purchaser’s designations.
GENERAL TEST METHODS
13. Scope
13.1 Except as otherwise specified in these test methods, the following ASTM test methods and the various test methods in Table
3, applicable in general to vulcanized rubber, shall be complied with as required and are hereby made a part of these test methods:
13.1.1 General Physical Test Requirements—Practices D3182 and D3183.
13.1.2 Aging Test—Test Method D573, with modifications as described in Sections 1615 – 2322 .
13.1.3 Compression Set, Suffıx B—Test method described in Sections 50 – 56.
13.1.4 Fluid Immersion, Suffıx E—Test Method D471 and Sections 2423 – 34.
13.1.5 Low-Temperature Test, Suffıxes F1, F2, and F3—Test method described in Sections 57 – 61. Suitable low-temperature
cabinets and conditioning procedures are described in Practice D832.
13.2 In case of conflict between provisions of the test methods referenced in 14.1.113.1.1 – 14.1.513.1.5 and the procedures
specifically described herein for cellular rubbers, the latter shall take precedence.
14. Test Specimens and Slabs
14.1 Test Specimens—Standard test specimens shall be disks 1.129 6 0.02 in. (28.67 6 0.50 mm) in diameter, which yields a
2 2 5
1-in. (645.16-mm ) specimen. The specimens may be cut with a revolving die using a soap solution as a lubricant. If a lubricant
is used, the specimens shall be thoroughly dried before proceeding with the testing. In some cases, it may be necessary to freeze
the cellular rubber to obtain parallel cut edges. Samples shall not be compression die cut because this process distorts the sample,
which will affect the final properties. When cut from standard test slabs they shall be cut from the center area as shown in Fig.
1. The thickness shall be measured as described in 15.3.214.3.2. As stated under the test methods, the The minimum thickness of
test specimens is 0.250 in. (6.35 mm). Plied-up samples may be used as indicated in the test methods for compression set and
compression deflection (see Note 3 in 19.218.2).
14.2 Test Slabs—Standard Where specially prepared standard test slabs of all types of cellular rubber shall be pieces nominally
6 in. (152.4 mm) square and nominally 0.5 in. (12.7 mm) in thickness made from the same compound and having the same apparent
density and state of cure as the product they represent. In all cases the surface skin shall be left intact on both top and bottom faces
of expanded rubber are required, they shall be made using the same process that was used for the product to be represented by
the test slab. Standard test slabs The specimens shall be prepared either by cutting them from flat sheets of the specified thickness
or as described to have approximately the same density, and shall be vulcanized under conditions of time and temperature chosen
to produce the same state of cure in 15.2.1 orthe standard 15.2.2.slabs as in the finished products they represent.
15.2.1 When specially prepared standard test slabs of sponge rubber are required, they shall be made using the frame shown in
Fig. 2 together with top and bottom plates each approximately 0.50 in. (12.7 mm) in thickness. The frame and plates shall be made
of aluminum or steel. The stock shall be in sheet form, cut into squares slightly smaller than the frame cavities. The thickness of
the square sheets shall be such as to give the required apparent density when the material is blown during cure to fill the molding
cavities. The squares of stock shall be dusted with talc and the excess brushed off to avoid pitting. They shall then be placed in
the frame, and fabric sheeting shall be applied on the top and bottom between the frame and the plates to allow venting of gases
2 2
produced during the cure. This fabric shall be a commercial sheeting with a mass of approximately 4 oz/yd (135 g/m ), having
approximately 70 ends/in. (2.75 ends/mm) and 60 picks/in. (2.36 picks/mm). The specimens shall be vulcanized in a platen press
under conditions of time and temperature chosen to produce the same state of cure in the standard slabs as in the finished products
they represent.
A satisfactory die and its method of application are described in Section 4 of Test Methods D575.
D1056 − 20
15.2.2 Where specially prepared standard test slabs of expanded rubber are required, they shall be made using the same process
that was used for the product to be represented by the test slab. The specimens shall be prepared to have approximately the same
density, and shall be vulcanized under conditions of time and temperature chosen to produce the same state of cure in the standard
slabs as in the finished products they represent.
14.3 Measurements of Test Specimens:
14.3.1 The length and width shall be measured to 0.02 in. (0.5 mm). Care shall be taken not to distort the cellular rubber.
14.3.2 Thicknesses up to and including 1 in. (25.4 mm) shall be measured using a dial-type gauge having a maximum stem and
foot mass of 25 g and a foot 1.25 in. (31.75 mm) in diameter. (See Section 69.) Thicknesses over 1.0 in. (25.4 mm) shall be
measured using a sliding caliper gauge. When a sliding caliper gauge is employed, the gauge setting shall be made with the gauge
out of contact with the cellular rubber. The sample shall be passed through the previously set gauge and the proper setting shall
be the one in which the measuring faces of the gauge contact the surfaces of the article without compressing it.
14.3.3 The steel scale or tape used to measure length or width shall be graduated to 0.039 in. (1 mm). The dial gauge for measuring
thickness shall be graduated to 0.001 in. (0.025 mm). The calipers used for measuring thickness shall be graduated to 0.005 in.
(0.127 mm).
14.3.4 Results shall be reported as the average of three measurements. If the results vary between the specimens more than 10 %,
two additional specimens should be taken into the average.
ACCELERATED AGING TESTS
15. Test Specimen
15.1 The test specimen used in any of the aging tests shall be of the size and shape as specified by the appropriate called-out test
method.
COMPRESSION-DEFLECTION TESTS
16. Scope
16.1 This test method consists of measuring the force necessary to produce a 25 % deflection on a test specimen.
17. Apparatus
17.1 Any compression machine that meets the following requirements will be satisfactory. The machine shall be An apparatus
capable of compressing the specimen at a rate of 0.5 to 2.0 in./min (12.7 to 50.8 mm/min) gently without impact. The machine
may be motor- or hand-driven. It shall be equipped with a gauge to measure the deflection caused by the increase in load. The rate
of compression of the specimen is specified rather than the rate of the compressing platform of the machine. This isbetween a flat
supporting plate and a flat compression foot that is larger than the specimen to be tested, at a uniform rate of speed of 1.25 6 0.5
in/min (31.75 6 12.7 mm an important consideration when scales are used, since sponges of various compression-deflection
characteristics will require different times to compress 25 % due to the travel of the scale platform under varying loads.⁄min). The
apparatus shall be capable of measuring the force required to produce the specified compression and the displacement of the
compression foot.
18.2 The deflection shall be read on a dial gauge graduated in 0.001 in. (0.025 mm). No gauge is necessary if the machine
automatically compresses the specimen 25 %.
18. Test Specimens
18.1 Standard test specimens can be used for this test.
18.2 Test specimen size may vary provided the indenter foot of the apparatus used is larger than the sample. Test specimens may
D1056 − 20
be cylindrical or square. They shall be cut so that opposite edges are parallel, either from the finished product or in a manner agreed
upon between the parties concerned or, as shown in concerned. Fig. 1, from standard test slabs or from flat sheets. The thickness
of the test specimens may vary, but shall be measured and stated in the report. The minimum thickness shall be 0.25 in. (6.35 mm).
Thin samples may be plied-up to obtain this thickness, or a standard test slab may be used if agreed upon between the manufacturer
and the purchaser.
NOTE 3—In sponge rubbers, using the same compound, thin sections under 0.25 in. (6.35 mm) do not blow in the same manner as those over 0.25 in.
(6.35 mm). The thinner sections are usually higher in compression deflection and density. However, in closed-cell (expanded) rubbers where thin sheet
areis split from thicker sheets there is usually very little difference between the thin sheet and thicker sheets.
19. Procedure
19.1 In accordance with 15.314.3, measure the width and length or diameter of the specimen to obtain the area of the specimen.
Measure the thickness of the specimen. Cellular rubber less than 0.250 in. (6.35 mm) in thickness shall be tested by plying up the
proper number of plies to obtain a thickness as near 0.50 in. (12.7 mm) as possible. Compress the standard test Preflex the specimen
by compressing the specimen between the parallel metal plates of the machine until the thickness has been reduced 25 %, and take
the reading of the load immediately. Repeat the test with the same specimen until the load readings do not change more than 5 %.
When repeating the test, do not re-measure the height of the specimen. The top and bottom plates shall be at least 1.5 in. (38.1
mm) in diameter, or if using larger test specimens than the standard specimen, the to
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