TPE Shore Hardness: A Selection Guide From 15 Shore A to 52 Shore D
Shore hardness measures a material's resistance to indentation, and it is the fastest way to narrow a TPE selection - but only within a single scale. The FARRPRENE catalogue spans 15 to 90 Shore A plus rigid grades at 40 to 52 Shore D. This guide maps each band to what it feels like, what it is typically used for, and which grades sit there.
Key takeaways
- Shore A covers soft, rubber-like materials; Shore D covers hard, rigid ones. The two scales are not comparable.
- A compound at 40 Shore D is considerably harder than one at 90 Shore A, despite the smaller number.
- Perceived softness in a handheld product usually lands between 55 and 70 Shore A.
- Below about 40 Shore A a visible surface marks and picks up dirt easily; above about 80 Shore A it stops reading as soft-touch.
- Hardness tells you nothing about strength, melt flow or weathering. Check those separately.
How the durometer scales work
A durometer presses a standardised indenter into the material under a defined force and reports how far it penetrates on a 0 to 100 scale. Shore A uses a blunt indenter suited to soft, elastomeric materials. Shore D uses a sharper one and a higher force, for harder materials where the Shore A scale saturates near its top end.
The scales overlap in the middle of their ranges but they are not interchangeable, and there is no reliable universal conversion between them - published conversion charts are approximations that depend on the polymer. That is why the two are kept separate throughout this catalogue.
15 to 30 Shore A: cushioning and damping
Gel-like to very soft. These compounds deform readily under thumb pressure and recover. They absorb more energy per unit deflection than anything firmer, which is what makes them the choice for vibration isolation and cushioning.
Grades: FARRPRENE IEU150A (15 Shore A, the softest here, and the only dual-process grade), FARRPRENE IU204A and FARRPRENE IU205A (20 Shore A), FARRPRENE IU250A and FARRPRENE IU251A (25 Shore A).
35 to 50 Shore A: seals, gaskets and soft overmoulds
Soft and rubbery, still compressing easily but with enough body to hold a moulded form. This is the compression-sealing band: soft enough to fill an irregular gap at low closure force, elastic enough to recover when the joint opens.
Injection grades: FARRPRENE IF350A, FARRPRENE IF402A, FARRPRENE IF453A, FARRPRENE IF454A, FARRPRENE IF458A, FARRPRENE IU450A, FARRPRENE IF500A. Extrusion grades: FARRPRENE EU400A, FARRPRENE EU401A, FARRPRENE EF455A, FARRPRENE EF456A, FARRPRENE EF457A, FARRPRENE EF501AU, FARRPRENE EU502A.
55 to 70 Shore A: the most specified band
Firm but clearly compliant. This is where most handle grips, weatherstrip, gaskets and cable accessories land, because it is the compromise that holds a sealing force while still reading as soft in the hand.
Injection grades: FARRPRENE IU550A, FARRPRENE IF602AU, FARRPRENE IU601A, FARRPRENE IF658AS, FARRPRENE IF700A, FARRPRENE IF701AS. Extrusion grades: FARRPRENE EF551AU, FARRPRENE EF600AU, FARRPRENE EF651A, FARRPRENE EF653AU, FARRPRENE EF654AU, FARRPRENE EF655A, FARRPRENE EF656AU, FARRPRENE EF657A.
75 to 90 Shore A: load-bearing flexible parts
Firm enough to carry load and resist permanent deformation, still flexible enough to bend without cracking. Bushings, spacers, pedal pads, firm grips and structural flexible components.
Injection grades: FARRPRENE IF750AS, FARRPRENE IF751A, FARRPRENE IF752A, FARRPRENE IF753A, FARRPRENE IF800AS, FARRPRENE IF801A, FARRPRENE IF850A, FARRPRENE IF852A, FARRPRENE IF900A, FARRPRENE IF901AS. Extrusion grades: FARRPRENE EF753AV, FARRPRENE EF820A, FARRPRENE EF902AV.
Shore D: rigid profiles and structural sections
Harder than the entire Shore A range. These behave closer to a flexible plastic than to a rubber: they carry load, hold their shape and resist deformation, while retaining impact resistance.
Grades: FARRPRENE EF400DV and FARRPRENE EF401DV (40 Shore D), FARRPRENE EF520DV (52 Shore D). All three are UV and heat stabilised extrusion grades. See the full Shore D range.
What hardness will not tell you
Two cautions. First, hardness is a weak predictor of strength: across the 46 Shore A grades here the correlation with tensile strength is only 0.57, and two grades at 90 Shore A differ by more than threefold in tensile. Second, hardness says nothing about processability - the seven grades at 45 Shore A span a factor of roughly 99 in melt flow.
All values quoted are typical average values from a limited sample set, not a formal specification. Request the signed datasheet for current values.
Scope note. The guidance on this page is based on published mechanical properties - hardness, tensile strength, elongation, melt flow, specific gravity, base polymer and stabilisation. Food contact, skin contact, biocompatibility, flame retardancy, halogen-free formulation and electrical performance are not characterised in the public catalogue and require a separately qualified compound and testing. Contact us to qualify a grade against any of those.
Frequently Asked Questions
What is the difference between Shore A and Shore D hardness?
They are different durometer scales using different indenters and forces. Shore A is for soft, rubber-like materials; Shore D is for harder, more rigid ones. A material at 40 Shore D is considerably harder than one at 90 Shore A, so the numbers cannot be compared directly and there is no reliable universal conversion between the scales.
What Shore hardness is best for a handheld grip?
Most handheld grips sit between 55 and 70 Shore A. Below roughly 40 Shore A the surface feels spongy and marks easily; above roughly 80 Shore A users stop perceiving it as soft-touch. The exact choice within that band depends on grip force and surface texture.
What hardness should a compression gasket be?
Typically 20 to 50 Shore A. The design aim is the softest compound that still recovers fully under the working compression, because a softer seal fills irregular surfaces at lower closure force and transmits less load into the mating parts.
Can I convert Shore A to Shore D?
Only approximately, and not reliably. Published conversion charts exist but they are approximations that vary with the polymer, so a converted figure should never be used as a specification. Where both scales matter, measure on the scale you intend to specify.
Does a higher Shore hardness mean a stronger part?
No. Hardness measures indentation resistance, not tensile strength. In this catalogue the correlation between Shore A hardness and tensile strength is only 0.57, and at 90 Shore A one grade publishes 17.5 MPa while another publishes 5.5 MPa. Read the tensile figure directly.
Related guides
- How to Choose a TPE Grade: A Specifier's Guide
- Shore A vs Shore D TPE: When Your Part Needs to Be Rigid
- Why Hardness Does Not Predict TPE Strength
- TPE Melt Flow Index: Why Injection and Extrusion Grades Are Not Interchangeable
About the FARRPRENE range
FARRPRENE is the thermoplastic elastomer (TPE) compound range of Farr Polychem FZCO, a polymer compounder based in Jebel Ali Free Zone, Dubai, United Arab Emirates, supplying the UAE, the wider MENA region and Europe. The range covers injection moulding and extrusion compounds from soft gel-like Shore A grades through rigid Shore D grades, in unfilled translucent and filled natural variants, colour-matchable to a customer reference, with free samples and technical datasheets available on request. Browse the full grade catalogue, see every grade side by side on the comparison table, or request a sample.
FARRPRENE GRADES
Grades commonly specified for industrial applications
| GRADE | HARDNESS | TENSILE (MPa) | TYPICAL USE |
|---|---|---|---|
| IEU150AInjection / Extrusion / Unfilled | 15 Shore A | 3 | Vibration-damping pads and soft mounts |
| IF752AInjection / Filled | 75 Shore A | 5.5 | Bushings, spacers and wear components |
| IF900AInjection / Filled | 90 Shore A | 5.5 | Hard bushings and near-rigid flexible parts |
Typical average values from a limited sample set; not a formal specification. Request the signed datasheet for current values.
MORE INSIGHTS
View All Articles