ISO 3386-2 is a laboratory test method for measuring the compression stress–strain characteristics of high-density flexible cellular polymeric materials (commonly high-density flexible foams and expanded cellular rubbers). It is used to characterize load-bearing behavior under compressive strain using a controlled compression test setup.
If you need help confirming whether ISO 3386-2 is the right fit for your material density range, specimen form, or reporting requirements, talk with our team about your application.
Flexible cellular polymeric materials — Determination of stress-strain characteristics in compression — Part 2: High-density materials (ISO 3386-2)
ISO 3386-2 focuses on the compressive stress–strain response of higher-density flexible cellular materials. It is typically referenced when a buyer or lab needs comparable compression curve points for denser flexible foams, where the stress rises steeply with strain and specimen geometry can strongly influence results.
This standard is part of the ISO 3386 series, where Part 2 is mainly oriented to higher-density materials and differs in approach from the low-density method in Part 1.
Quick Definition
Document type: Test method.
In one sentence: ISO 3386-2 defines how to compress a high-density flexible cellular polymeric test piece and report stress values at specified compressive strains to describe the material’s compression stress–strain characteristic.
Common output: Stress values (kPa) at defined compressions from a stress–strain curve, used as a measure of load-bearing behavior under compression (not necessarily long-term load performance).
What This Standard Covers
ISO 3386-2 specifies a method to determine compression stress–strain characteristics for flexible cellular polymeric materials primarily in a higher-density range (commonly cited for materials above 250 kg/m³). The method is used to generate comparable stress values on the steeply rising portion of the stress–strain curve.
Because results depend strongly on specimen geometry, the standard emphasizes comparability only when test pieces have the same shape factor. Part 2 also restricts certain specimen forms compared with other foam compression approaches.
Why This Standard Matters in Testing
Compression behavior is often a make-or-break property for cellular materials used in load-bearing or support functions. ISO 3386-2 provides a structured way to compare materials and batches using a consistent compression procedure, rather than relying on informal “feel” or non-comparable hardness readings.
It is also useful when you need a compression stress–strain characteristic that is distinct from indentation hardness testing, which can be influenced by test-piece thickness, tensile properties, and indenter / platen geometry effects.
Common Materials, Product Types, or Applications Covered
ISO 3386-2 is commonly applied to denser flexible cellular polymeric materials where compression performance is central to function.
Common materials: High-density flexible polymer foams; expanded cellular rubbers and similar flexible cellular materials.
Common use cases: Incoming quality control, supplier qualification, formulation or process change validation, comparative benchmarking of compression behavior, and product verification where compressive load-bearing response is specified.
Common Test or Verification Workflow
A typical ISO 3386-2 workflow is built around controlled specimen conditioning and a repeatable compression sequence so stress values at specified compressions can be compared across lots and suppliers.
Common workflow steps:
- Prepare test pieces with controlled geometry appropriate for compression testing, keeping shape factor consistent when comparing results.
- Condition specimens in a controlled laboratory atmosphere prior to testing (the cited edition may set minimum conditioning and “time after manufacture” requirements, including options for quality-control timing).
- Compress the specimen between platens at a controlled deformation rate and capture force vs. displacement/strain data.
- Report compression stress values at specified compressions/strains as required by the cited edition.
Equipment Commonly Used for This Standard
ISO 3386-2 is typically run on a compression-capable universal testing machine (or equivalent compression test frame) configured for foam/rubber compression work, with appropriate platens and data capture.
Common equipment:
- Universal testing machine / compression test frame: Capable of applying controlled compressive deformation and recording force and displacement continuously.
- Compression platens: Flat, rigid platens sized and aligned for stable specimen loading.
- Force measurement performance: The amendment to ISO 3386-2 references force measurement accuracy aligned with ISO 7500-1 class requirements (commonly class 2 or better), which can affect load cell selection and calibration approach.
- Specimen measurement tools: Calipers or thickness/size measurement tools aligned with dimensional measurement practices (ISO 1923 is referenced as a normative document in the standard).
- Conditioning environment (as needed): Controlled temperature and humidity space to condition and test at defined atmospheres when required.
If you are selecting a compression system, platen size/alignment, and force range for high-density flexible foams, you can request a detailed quote for a configuration matched to your specimen size and target stress range.
How to Read This Designation or Revision
Base standard: ISO 3386-2:1997 is the primary document for this method and is identified as an International Standard.
Amendment: ISO 3386-2:1997/Amd 1:2010 exists and may be required depending on how your customer or internal specification cites the method.
Practical tip: When a purchase order or customer drawing references “ISO 3386-2” without a year, confirm whether the 1997 edition alone is intended or whether the 2010 amendment is expected to apply (this can affect conditioning requirements and force-measurement expectations).
Related Standards, Methods, or Frameworks
ISO 3386-2 is commonly used alongside other foam and cellular material test references, especially when a specification calls out both compression behavior and hardness or dimensional controls.
Frequently paired references within the standard’s context:
- ISO 3386-1: Part 1 covers low-density flexible cellular materials and is often cited when the density range or specimen behavior is different.
- ISO 2439: Indentation hardness method often referenced to distinguish indentation hardness from compression stress–strain characteristics.
- ISO 1923: Dimensional measurement practices for cellular plastics and rubbers (used to support consistent specimen measurement).
- ISO 7500-1: Referenced for force-measurement verification of testing machines, relevant to compression force accuracy expectations.
Talk to Us About ISO 3386-2 Test Setups
If you are standardizing ISO 3386-2 across multiple labs or suppliers, contact our team to discuss force range, platen sizing, conditioning needs, and how to align the test setup to the exact cited edition (including any amendment).