ASTM D3574 vs ISO: Foam Test Method Cross-Reference
One buyer’s specification calls for “ASTM D3574 Test B1”, another for “ISO 2439 method A”. Purchasing teams often treat them as interchangeable, and labs are then surprised when the same foam produces two different numbers. This article maps each ASTM D3574 test to its ISO counterpart, explains which pairs are truly equivalent and which only measure the same property in a different way, and shows how to report results so they can be compared. For the bigger picture, see our foam testing guide.
ASTM D3574 vs ISO: one standard against many
ASTM D3574 collects the test methods for flexible polyurethane foam under a single standard, with each method identified by a letter: density is Test A, indentation force deflection is Test B1, tensile is Test E. ISO works the other way round. Each property has its own standard, such as ISO 845 for density, ISO 2439 for hardness and ISO 1798 for tensile properties.
ASTM D3574 says this plainly in its own scope: there’s no ISO equivalent to the standard as a whole, although several of its test methods have similar or equivalent ISO standards. In practice, North American buyers write specifications with ASTM letter codes, while buyers in Europe, the Middle East and much of Asia usually quote ISO numbers.
ASTM D3574 to ISO cross-reference table
| Property | ASTM D3574 | ISO | Relationship |
|---|---|---|---|
| Density | Test A | ISO 845 | Equivalent |
| Indentation hardness | Test B1 (IFD), Test B2 (IRGL) | ISO 2439 | Same subject, results not directly comparable |
| Compression force deflection | Test C | ISO 3386 | Same subject, results not directly comparable |
| Compression set | Test D | ISO 1856 | Same subject, results not directly comparable |
| Tensile strength and elongation | Test E | ISO 1798 | Same subject, results not directly comparable |
| Tear resistance | Test F | ISO 8067 | Same subject, results not directly comparable |
| Air flow | Test G | ISO 7231 | Similar method |
| Resilience (ball rebound) | Test H | ISO 8307 | Similar method |
| Dynamic fatigue (constant force pounding) | Test I3 | ISO 3385 | Similar method |
| Accelerated aging | Tests J, K, L | ISO 2440 | Similar subject |
The relationship wording in the first six rows comes from the notes in ASTM D3574 itself. The last four rows pair methods that measure the same property on a similar principle. That pairing is common practice, but the standard doesn’t make a formal equivalence statement for them.
Equivalent vs same subject: why the difference matters
The most useful detail in that table is how few pairs are actually equivalent. ASTM D3574 declares equivalence with ISO only for density. For the other methods, its wording is that they address the same subject as the ISO standard but differ in technical content, so results can’t be directly compared.
Hardness is the clearest example. ASTM Test B1 usually reports force at 25% and 65% indentation on a 100 mm thick specimen, while ISO 2439 method A reads force at 40% indentation on a thinner sample. The same foam gives two different numbers, and both are correct. We explain how to read those IFD values in IFD vs ILD. Similar differences in specimen size, test speed and conditioning time apply across the other tests.
How to state the standard in a test report
“Tested to ASTM” or “ISO compliant” isn’t enough for a report that someone else will compare against. A usable report states at least:
- Standard number and test code: for example “ASTM D3574 Test B1” or “ISO 2439 method A”.
- Edition year: methods change between revisions.
- Specimen dimensions and thickness: these affect hardness and compression results directly.
- Conditioning: temperature, relative humidity and duration.
- Deviations: any non-standard specimen size or speed, stated explicitly.
Which standard should you test to?
The rule is simple: test to whatever standard the customer’s specification names. Producers selling into North America generally test to ASTM D3574, while those selling into Europe and the Middle East mostly use ISO. Automotive manufacturers write their own specifications, and these usually reference ISO methods.
If you sell into both markets, the safest approach is to measure your critical properties to both methods and build up a record of how the two relate for your own formulations. That record isn’t a conversion formula. It only holds for the foam you measured.
Which tests Vilutra equipment covers
Vilutra’s testers are built for three of the methods in the table. The MK-1040 Foam Resilience Tester measures ball rebound to ISO 8307 and ASTM D3574 Test H. The MK-1070 Foam Tensile Tester covers tensile strength and elongation under ISO 1798 and ASTM D3574 Test E. The MK-1090 Foam Fatigue Tester runs dynamic fatigue tests to ISO 3385. All three are designed and built in Türkiye and serviced from İzmir.
Frequently asked questions
Is ASTM D3574 the same as ISO?
No. ASTM D3574 groups many test methods in one standard, while ISO has a separate standard for each property. Only the density test, Test A and ISO 845, is treated as equivalent.
Can I convert an ASTM result into an ISO result?
There’s no reliable conversion. Specimen size, indentation level and hold time differ, so the only safe comparison is to retest to the same method.
Is ASTM D3574 Test I3 the same as ISO 3385?
Both pound the foam repeatedly under a constant force and measure thickness and hardness loss, so the principle is the same. Don’t assume the parameters match, and always state which method was used.
Will density come out the same under both standards?
Because ASTM D3574 Test A and ISO 845 are treated as equivalent, results should agree when the specimen is prepared and conditioned the same way. If they don’t, check first whether the skin was removed and how long the sample was conditioned.