What Is Shore?
Shore hardness test is a test in which the hardness value is read from the indentation depth by pressing the sample surface with a standard penetrating and spring-loaded durometer. Shore A is used in soft elastomers, Shore D is used in hard plastic and hard rubber.
Purpose of Shore
The purpose is to verify batch consistency and specification compliance by checking the hardness of the elastomer or plastic.
Which Products Is Shore Applied To?
- Gaskets and sealing elements
- Hose and profiles
- shoe sole materials
- Hard plastic parts
In Which Sectors Is Shore Used?
Standards Related to Shore
- ISO 868
- ISO 7619-1
- ASTM D2240
Shore Conditions
- Scale
- Shore A (soft) or Shore D (hard); is selected according to the material
- Specimen thickness
- Minimum thickness defined in the standard (typically at least 6 mm; layering if necessary)
- reading time
- Defined in the standard; instant or after defined waiting
- Number of measurements
- A defined number of measurements at different points; median or mean is given
Equipment for Shore
- Shore A and Shore D durometers
- Measuring stand (constant load application)
- Kalibre referans bloklar
- Thickness measuring instrument
Sample Requirements for Shore
- The sample surface must be flat and smooth
- Minimum thickness must be ensured; If stratification is done, it should be reported
- Measurement points must be at a distance defined in the standard from the edge
- The sample must be conditioned
Duration of Shore
Typically 1 day.
Shore Procedure
- 1The durometer is verified with reference blocks.
- 2Specimen thickness is measured.
- 3The sample is placed on a flat surface.
- 4Measurements are made at a defined number of points.
- 5Values are recorded according to the reading time.
- 6The result is reported by specifying the scale.
Shore Acceptance Criteria
The acceptance criterion is the hardness range given in the specification (e.g. 70 ± 5 Shore A).
Evaluation of Results
Shore A and Shore D values cannot be converted to each other and a hardness value given without a scale is meaningless. Insufficient sample thickness overestimates hardness; stratification affects the outcome and should be reported.
Shore Report
- Applied standard and scale
- Sample thickness and layering
- reading time
- Individual measurements and the result
- Conditioning conditions
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
- Material and product specifications
Plastics Testing — What Does This Testing Field Cover?
The section below describes the field that the Shore 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.
Plastics testing determines the mechanical, thermal and burning behaviour of a polymer material. Unlike metals, plastics are VISCOELASTIC: their behaviour depends on loading rate, temperature and moisture. The same material therefore gives different results under different conditions, and the test conditions are an inseparable part of the result.
The practical consequence of viscoelasticity is this: a plastic part continues to deform over time under a constant load (creep) and the stress it carries at constant deformation falls over time (stress relaxation). A screwed joint loosens, a clamp loses its clamping force, a shelf sags over time. A short-term tensile test does not show this behaviour; a long-term test or an accelerated model is needed.
Thermal behaviour is the second main axis. Melt flow rate indicates the processability of the material and lot-to-lot consistency; heat deflection temperature and the Vicat softening point give a rough limit for service temperature. Thermal analysis (DSC, TGA, DMA) reveals the identity of the material: glass transition temperature, melting behaviour, crystallinity, filler content and decomposition temperature.
Burning behaviour is the third axis and ties directly into product standards. The UL 94 class and the limiting oxygen index are written into the material data sheet; a particular class is required for the housing of an electrical appliance, while a different classification system applies to a construction product.
Ageing is the most frequently skipped part of the field. Plastics degrade under UV, heat, moisture and oxygen: colour changes, the surface cracks, impact strength falls. For a part intended for outdoor use, what matters is not its values on day one but its values after ageing. Xenon arc and fluorescent UV equipment accelerate this degradation and allow comparison.
The output of this family is usually written into the material data sheet, and product standards refer to that sheet. But there can be a difference between the data sheet value and the behaviour of the actual part: orientation formed during moulding, weld lines and internal stresses make the part behave differently from the specimen.
The use of recycled content has added a new question to the field. Recycled resin varies from lot to lot; mechanical properties, colour and burning behaviour can shift between batches. For a manufacturer using recycled material, incoming material control is therefore not a choice but a necessity.
Method groups in this field
Mechanical
Tension, compression, bending, Charpy and Izod impact, hardness (Shore), creep and environmental stress cracking.
Thermal
Melt flow index (MFI), heat deflection temperature (HDT), Vicat softening temperature, linear thermal expansion.
Thermal analysis
Transition temperatures and crystallinity by DSC, composition and decomposition by TGA, dynamic mechanical behaviour by DMA.
Burning
UL 94 classification, limiting oxygen index (LOI), glow wire and needle flame tests.
Ageing
Accelerated ageing by xenon arc and fluorescent UV, hot air ageing, humidity and condensation.
Physical
Density, water absorption, ash content, gas and water vapour permeability of films and sheets.
Commonly confused in this field
- A plastics result without a stated test rate and temperature cannot be interpreted; viscoelastic behaviour depends on these parameters.
- A specimen result does not transfer directly to the actual part; moulding orientation and weld lines are decisive.
- HDT and Vicat values are NOT service temperatures; they are a rough indication of an upper limit and do not apply under load.
- The UL 94 class depends on thickness; a different wall thickness requires re-verification.
- For moisture-absorbing polymers (such as polyamide), results are misleading unless conditioning is carried out.
- ASTM D638 and ISO 527 results are not directly equivalent; the specimen geometries and rate definitions differ.
Which decisions these results support
- Material selection and supplier approval
- Meeting the flammability and thermal requirements of the product standard
- Verifying the use of recycled content and lot control
- Moulding process control and lot consistency
- Demonstrating ageing resistance for outdoor use
Related Tests
Frequently Asked Questions About Shore
Are Shore A 90 and Shore D 40 the same hardness?
These values are read on different scales and cannot be directly translated. For materials located in the overlap zone, the standard defines which scale to use; The report should indicate the scale.