OTR – ASTM D3985

What Is OTR — ASTM D3985?

The OTR test measures the amount of oxygen passing through a film per unit area and unit time. The specimen is mounted separating two chambers; oxygen is fed to one side and carrier gas to the other, and the oxygen passing through is measured with a coulometric sensor. The result is given in cm³/m²/day.

Purpose of OTR — ASTM D3985

The purpose is to determine the packaging's oxygen-barrier function and provide data for the shelf-life calculation of oxidation-sensitive products. Oxygen is the main cause of fat oxidation, colour loss and vitamin degradation.

Which Products Is OTR — ASTM D3985 Applied To?

Barrier packaging films
EVOH and metallised structures
Modified-atmosphere packaging films
PET bottles and containers
Pharmaceutical blister foils

In Which Sectors Is OTR — ASTM D3985 Used?

PackagingLogisticsRetailFoodPharmaceuticals

Standards Related to OTR — ASTM D3985

ASTM D3985oxygen permeability (OTR) test

OTR — ASTM D3985 Conditions

Temperature and humidity: Defined in the standard; 23 °C and a defined relative humidity are commonly used
Humidity effect: For barriers such as EVOH, OTR rises markedly as humidity increases
Equilibrium: The measurement continues until a steady transmission rate is reached

Equipment for OTR — ASTM D3985

OTR tester (coulometric sensor type)
Humidity control unit
Package-level measurement fixtures
Gas supply system

Sample Requirements for OTR — ASTM D3985

Flat film specimens free of holes and wrinkles
The specimen must fully cover the measurement cell
Film structure, thickness and barrier layer information must be provided
A sealed package must be supplied if package-level measurement is required

Duration of OTR — ASTM D3985

The measurement runs until equilibrium is reached. For high-barrier structures the amount of oxygen passing through is very low, so the equilibration time extends markedly and the measurement can take days.

OTR — ASTM D3985 Procedure

1The specimen is cut and placed in the measurement cell without leaks.
2The system is purged with carrier gas.
3Temperature and humidity conditions are brought to equilibrium.
4Oxygen is fed to one side.
5The oxygen passing through is continuously monitored by the sensor.
6The result is recorded once a steady value is reached.

OTR — ASTM D3985 Acceptance Criteria

The acceptance criterion is the maximum OTR value in the specification. The limit is set according to the product's sensitivity to oxidation and the target shelf life.

Evaluation of Results

An OTR value given without stating the humidity condition is misleading: the permeability of barrier polymers such as EVOH rises markedly with humidity, so an excellent value obtained under dry conditions may not represent real use. Film measurement also does not represent the whole package.

OTR — ASTM D3985 Report

Specimen identification, thickness and layer structure
Measurement temperature and relative humidity condition
Standard and method applied
OTR result (cm³/m²/day) and measurement uncertainty
Barrier layer orientation

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

EU 94/62/EC Packaging and Packaging Waste Directive
Regulation on the Control of Packaging Waste
EU 1935/2004 (materials in contact with food — where applicable)

Ambalaj Testleri — What Does This Testing Field Cover?

The section below describes the field that the OTR test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Packaging testing examines two different functions separately: does the packaging protect the product during transport, and does the packaging material transfer harmful substances into its contents? These two questions require different laboratory infrastructure and must not be confused.

On the protection side, distribution simulation is carried out: drop, vibration, compression, stacking and, where needed, low pressure tests are applied in sequences representing the real shipping chain. These tests are meaningful as a SEQUENCE rather than individually; in real life too, packaging is exposed to successive loads and each load builds on the damage left by the previous one. Specifications such as ISTA and ASTM D4169 define these sequences by shipment type.

The shipment type determines the sequence itself. The exposure of a palletised load differs from that of a parcel shipped individually: the latter sees far more handling, more drops and impacts in a wider variety of orientations. The growth of e-commerce has brought this second scenario to the fore and turned parcel shipping simulation into a specification group of its own.

On the food contact side, MIGRATION is what counts: the amount of substance passing from the packaging material into the food is compared against overall and specific migration limits. For plastic packaging the list of permitted substances and the limits are defined in separate legislation; the declaration of conformity (DoC) rests on this assessment and is a document that every link in the supply chain must carry.

In a migration test the choice of SIMULANT is critical. Because testing with real food is not practical, liquids representing food are used: different simulants for aqueous foods, for fatty foods and for acidic foods. Choosing the wrong simulant invalidates the result; the choice depends on which food type the packaging will contact and at what temperature.

Barrier properties are a third axis. Oxygen and water vapour permeability directly determine the shelf life of the product; in pharmaceutical and food packaging these values are a design input. Barrier performance is sensitive to temperature and relative humidity, so the measurement conditions are part of the report.

Sterile medical device packaging is the most tightly regulated sub-body of this family. Here the packaging is a barrier maintaining sterility; seal strength, leak testing, distribution simulation and shelf-life studies run together as a validation package.

The packaging legislation side is becoming rapidly more demanding. Recyclability, recovered content ratio, packaging reduction and reuse targets must now be measurable and declarable; this turns packaging design from a material selection exercise into a conformity exercise.

Method groups in this field

Distribution simulation
Drop, random and fixed frequency vibration, compression, stacking, low pressure; as ISTA and ASTM D4169 sequences.
Mechanical strength
Edge crush (ECT) in corrugated board, bursting strength, box compression strength, tape peel adhesion.
Barrier measurements
Oxygen transmission rate (OTR), water vapour transmission rate (WVTR), permeability in film and sheet materials.
Migration
Overall and specific migration tests; simulant and temperature conditions are chosen according to the use scenario.
Seal and integrity
Seal peel strength, leak detection by dye penetration, bubble test, headspace analysis.
Shelf life
Real-time and accelerated ageing; part of the validation package in sterile packaging.

Commonly confused in this field

A single drop test is not a distribution simulation; the tests are applied as the sequence defined in the specification.
A migration test carried out with the wrong simulant or the wrong contact temperature is invalid.
Accelerated ageing does not replace real-time ageing; a shelf life claim is supported by real-time data.
Barrier values are valid together with the measurement temperature and relative humidity; an OTR/WVTR value given without conditions cannot be compared.
A packaging change (film supplier, seal parameter, box design) may require the validation to be repeated.
A food contact declaration of conformity is not a test report; it is a document that rests on reports but summarises a broader assessment.

Which decisions these results support

Reducing shipping damage and verifying the packaging design
Declaration of conformity for food contact packaging
Supporting the shelf-life claim
Validation of sterile device packaging
Recyclability and content declarations under packaging legislation

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Frequently Asked Questions About OTR — ASTM D3985

Why does the humidity condition matter so much?

Common barrier polymers such as EVOH and polyamide absorb moisture, and their oxygen permeability rises as they take up moisture. A low OTR measured under dry conditions may not hold in contact with moist food. The condition is therefore always reported.

When is package-level measurement needed?

When the package's real performance is in question. The film value is a material property; in a sealed package, seal areas, the lid and the closure system also transmit oxygen. Package-level measurement is more realistic for shelf-life verification.