Written and maintained by CASRAI Editorial Board
Last updated
Short answer
ASTM D1056 is the ASTM International specification for flexible cellular rubber, the materials sold as sponge rubber and expanded rubber. It sorts them by type, class and grade and points to a set of test methods. The current edition is D1056-20, issued by Committee D20 (subcommittee D20.22). It is a material specification, not a product: it does not name a seal, gasket or pad, and the requirement tables sit in the full standard text.
Definition and scope
The title of the current edition is Standard Specification for Flexible Cellular Materials – Sponge or Expanded Rubber. Searchers type it as “ASTM D1056” or “ASTM D 1056”; both refer to the same designation. According to the ASTM abstract, the specification covers flexible cellular rubber products known as sponge rubber and expanded rubber, and the base material can be synthetic, natural or reclaimed rubber, or a mixture of them.
Two things fall outside the standard. The scope excludes latex foam rubber and ebonite cellular rubber. It also notes that extruded or molded shapes too small to provide standard test specimens are hard to classify or test under these methods and usually need special procedures.
How the standard is used in practice
A specification like D1056 works as a shared vocabulary. A buyer or engineer cites the designation, and the edition, so that the supplier and the purchaser describe the same material by the same type, class and grade. The classification axes in the abstract are:
- Types: Type 1 and Type 2.
- Classes: A, B, C and D.
- Grades: 0 through 5.
- Suffixes: the abstract states that suffix letters exist, but it does not list them, so their meaning is a question for the full text.
The abstract also lists the test families the standard draws on. Reading them as a group shows what the standard is concerned with.
The seven test families in the abstract
| Test family listed | Where the abstract places it |
|---|---|
| Accelerated aging | Listed as a test |
| Compression-deflection | Listed as a test |
| Oil immersion | Applies to open-cell sponge |
| Fluid immersion | Applies to closed-cell rubber |
| Water absorption | Listed as a test |
| Density | Listed as a test |
| Low-temperature flex | Listed as a test |
The one distinction the abstract draws explicitly is between open-cell sponge, where the immersion test uses oil, and closed-cell material, where it uses a fluid. The pass or fail numbers for each family are not in the abstract.
Types, classes and grades
The three classification axes give the specification its structure. Type has two values, class has four and grade has six, so a callout such as a type, class and grade triplet identifies one material description within the standard. What those letters and numbers mean in terms of properties is defined in the full text. Because that text is sold by ASTM, this page does not reproduce any property values or tables from it, and nobody should infer a grade’s properties from its number.
Where it matters for labs, clinics and supply decisions
For a purchasing or quality role, the practical content of the abstract is a short checklist of what to confirm before relying on a D1056 citation:
- Edition. ASTM lists earlier versions of this standard: D1056-14, D1056-07, D1056-00 and D1056-68E01. The current edition is D1056-20, which the ASTM store lists as active. A specification that cites only “D1056” without the year leaves the edition open. See FDA Recognized Consensus Standards for another case where the exact edition of a standard is what gets cited.
- Material family. The scope is sponge and expanded rubber. If the item is latex foam rubber or ebonite cellular rubber, D1056 is not the governing standard.
- Size of the part. The scope states that very small extruded or molded shapes may need special procedures, so a small profile does not automatically fit the standard test approach.
- Units. The standard states that inch-pound values are the standard and SI values in parentheses are for information only.
- Full text. The classification meanings and requirement values live in the purchased standard, so a requirement should be checked there before it is written into a specification.
The same habit of recording which edition and which procedure applies is part of documented procedures generally; see standard operating procedure (SOP) and the guide to RFPs for lab and research equipment procurement. To keep material specifications tied to an item over its service life, lab equipment lifecycle assessment covers the broader record-keeping.
Common misunderstandings
“D1056 describes a specific product”
It describes a material category and how to classify it. It does not describe a gasket, seal, pad or any finished part.
“It covers all foam rubber”
The scope names latex foam rubber and ebonite cellular rubber as excluded.
“The public abstract is the requirement”
The abstract states scope, categories and which tests exist. The requirement values are in the standard text, so quoting a grade’s properties from the abstract or from a summary would be guessing.
“The SI numbers are the standard”
The standard says inch-pound units are regarded as standard and the SI figures are for information.
FAQ
What does ASTM D1056 cover?
Flexible cellular rubber products known as sponge rubber and expanded rubber, classified by type (1 and 2), class (A to D) and grade (0 to 5), with test methods for aging, compression-deflection, immersion, water absorption, density and low-temperature flex.
Is ASTM D 1056 the same as ASTM D1056?
Yes. The spacing differs; the designation is the same. The edition year, such as -20, is what tells editions apart.
What is the current edition?
D1056-20 is the edition the ASTM store lists as active, with the page last updated on 4 November 2020. The New Zealand Building CodeHub, a portal run by MBIE, Standards New Zealand and BRANZ, separately summarises the D1056-00 edition, which shows the scope and categories were already in place then.
Which ASTM committee maintains it?
Committee D20, through subcommittee D20.22, per the ASTM store page.
Sources
- ASTM International, D1056-20, Standard Specification for Flexible Cellular Materials – Sponge or Expanded Rubber (store page and abstract; date checked 29 October 2026).
- New Zealand Building CodeHub (MBIE, Standards New Zealand, BRANZ), ASTM D1056-00 summary (date checked 29 October 2026).
Requirement values are in the standard itself, available from ASTM.
