ISO 815-1 describes laboratory methods used to measure compression set in vulcanized and thermoplastic rubber after being held under a defined constant strain at ambient or elevated temperature.
It is commonly referenced when evaluating sealing performance (for example, gaskets and O-rings) and when comparing compounds for quality control, incoming inspection, or material qualification. If you are aligning a test setup to a customer or drawing requirement, talk with our team about the cited method and temperature conditions.
ISO 815-1: Rubber, vulcanized or thermoplastic — Determination of compression set — Part 1: At ambient or elevated temperatures
ISO 815-1 is a test-method standard for determining how well a rubber test piece recovers after prolonged compression at a specified temperature. Results are used to compare elastic recovery behavior across materials and cure states under controlled conditions.
The standard includes one ambient-temperature method and multiple elevated-temperature methods (identified as methods A, B, and C) that differ by how the test piece is released at the end of the test.
Quick Definition
Standard type: Test method (compression set under constant strain).
What it measures: Permanent deformation remaining after a rubber specimen is compressed for a set time at a set temperature and then allowed to recover.
Typical control variables: Compression strain (commonly 25%), temperature (ambient or elevated), time under compression, and recovery conditions.
What This Standard Covers
ISO 815-1 specifies methods to determine compression set characteristics of vulcanized and thermoplastic rubbers at ambient temperature (one method) or elevated temperature (methods A, B, and C). It is intended for rubbers in a stated hardness range and uses a constant-strain approach where the test piece is compressed to a defined deflection and held for a defined duration.
The compression strain is normally 25%. For harder rubbers, the standard uses reduced compression strain values (15% or 10%, depending on nominal hardness) to keep deformation and measurement within a practical range.
Why This Standard Matters in Testing
Compression set is a key screening metric for rubber components that must maintain contact pressure after long-term compression, particularly sealing elements. It is frequently used to compare compound formulations, support material approval decisions, and demonstrate batch-to-batch consistency.
Because elevated-temperature exposure can accelerate changes that reduce recovery, the method selection and temperature condition strongly influence how results should be interpreted for product use.
Common Materials, Product Types, or Applications Covered
ISO 815-1 is commonly applied to vulcanized rubber and thermoplastic rubber materials used in components where elastic recovery after compression is important.
Common examples: O-rings, gaskets, seals, vibration-isolation elements, and rubber pads where long-term compression and temperature exposure are relevant to performance.
Common Test or Verification Workflow
Most lab workflows using ISO 815-1 follow a consistent pattern: condition and measure the specimen, apply a defined constant strain using a compression device and spacers, hold at the specified temperature for the specified duration, then release and measure recovery according to the selected method.
Common workflow steps: Initial thickness measurement, compression to the required strain, temperature exposure at ambient or elevated temperature, controlled release per the selected method (A/B/C at elevated temperature), recovery period as required, and final thickness measurement for compression set calculation.
Equipment Commonly Used for This Standard
ISO 815-1 is typically supported by dedicated compression set tooling and temperature control equipment. The exact configuration depends on specimen shape, thickness, throughput needs, and the chosen temperature condition.
Common equipment: Compression set fixture(s) with parallel plates and spacers (to control strain), a temperature-controlled oven or chamber for elevated-temperature exposure, calibrated thickness measurement tools (for before/after readings), and timing/handling accessories to support consistent recovery conditions.
If you are selecting fixtures, spacer stacks, or chamber capacity for a specific sample size and throughput, you can request pricing for a compression set setup matched to your lab workflow.
How to Read This Designation or Revision
ISO 815-1 identifies Part 1 of the ISO 815 series covering compression set at ambient or elevated temperatures.
When a year is included (for example, ISO 815-1:2019), it indicates a specific published edition. ISO 815-1:2019 is the published third edition, and the prior ISO 815-1:2014 edition has been withdrawn. Test setup details and reporting expectations can vary by edition, so purchase orders, customer specs, and quality plans should cite the exact edition being used.
Related Standards, Methods, or Frameworks
Compression set requirements are often specified alongside other rubber material property tests, depending on the end-use environment.
Common related reference: ISO 815-2 (Part 2) covers compression set determination at low temperatures and may be used when seals or elastomer components must recover after cold exposure.
Get help selecting compression set fixtures and temperature equipment
If you share the cited ISO 815-1 edition, method (ambient or A/B/C), target temperature, and specimen dimensions, we can recommend a practical equipment path for your lab. To price a complete configuration, ask for a detailed quote.