What Is Peel?
The peel strength test measures the force required to separate two bonded layers at a defined angle and constant speed. In packaging, it shows a laminate film's resistance to delamination; for labels, it shows the adhesive's grip on the surface.
Purpose of Peel
The purpose is to determine the laminate structure's resistance to layer separation and the label adhesive's performance. Delamination causes the barrier layer to lose its function and the product to spoil.
Which Products Is Peel Applied To?
- Laminated flexible packaging films
- Labels and adhesive tapes
- Lidding films
- Metallised and aluminium-foil structures
- Easy-peel packaging
In Which Sectors Is Peel Used?
Standards Related to Peel
- ASTM D903 (peel or stripping strength of adhesive bonds)
- TS EN ISO 8510-1/-2 (90-degree and 180-degree peel)
- ASTM F88 (seal strength of flexible barrier materials)
- FINAT FTM 1 (label peel adhesion)
- ISTApackaging transport performance test series test
Peel Conditions
- Peel angle
- 90° or 180°; the result varies with the angle and is reported
- Tensile speed
- Constant speed defined in the standard
- Dwell time
- A defined dwell time for the adhesive to bond to the surface, for labels
Equipment for Peel
- Tensile tester
- 90-degree peel fixture
- Specimen cutter
- Conditioning chamber
Sample Requirements for Peel
- Strips cut to the defined width
- For labels, the specimen together with the surface it will be applied to
- Film structure and layer sequence must be provided
- Curing must be complete after bonding or lamination
Duration of Peel
The test is short; for label applications, the time waited for the adhesive to bond sets the total duration.
Peel Procedure
- 1Specimens are conditioned and cut to the defined width.
- 2The layers are separated at a starting section.
- 3The specimen is mounted in the machine at the angle defined in the standard.
- 4It is pulled at constant speed and the force is recorded.
- 5The average force in the steady-state region is calculated.
- 6The mode of separation and surface condition are recorded.
Peel Acceptance Criteria
The acceptance criterion is the minimum peel strength in the specification. For easy-peel packaging, both a lower and an upper limit are defined: it must hold securely enough yet still open easily by hand.
Evaluation of Results
The smoothness of the force-distance curve is also assessed: a wavy curve points to uneven adhesive distribution in the laminate. Which layers the separation occurs between is recorded, showing which layer is problematic.
Peel Report
- Specimen identification and film layer structure
- Standard applied and peel angle
- Individual and average force values
- Mode of separation and layer information
- Force-distance curve
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 authorisationsRelated 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 Peel 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
Related Tests
Frequently Asked Questions About Peel
Can 90-degree and 180-degree results be compared?
No. The angle changes the geometry of force application, and the same specimen gives a different value at the two angles. The specification must state which angle is required.