PORON Medical® Urethanes — Slow Recovery
PORON Medical® Slow Recovery Urethanes are open-cell, breathable viscoelastic polyurethane foams available in four color-coded firmness grades — Very Soft (MSRVS), Soft (MSRS), Firm (MSRF), and Very Firm (MSRVF) — all at 15 lb/ft³ (240 kg/m³) density. Compression force deflection ranges from 0.3–3.5 psi (2–24 kPa) for the Very Soft grade to 4–22 psi (27–151 kPa) for the Very Firm grade at 25% deflection. All grades pass ISO 10993-10:2010 primary skin irritation and do not promote fungal growth per ASTM G21. Recommended constant use temperature is 70°C (158°F).
Key Properties
- Compression Force Deflection, psi (kPa): 0.3–3.5 (2–24) / 1.5–6.5 (10–45) / 3–18 (21–124) / 4–22 (27–151) at MSRVS / MSRS / MSRF / MSRVF; 0.2″/min. Strain Rate, Force @ 25% Deflection
- Tensile Strength, psi min. (kPa): 15 (104) / 40 (276) / 80 (552) / 100 (689) at MSRVS / MSRS / MSRF / MSRVF; ASTM D3574, Test E
- Tensile Elongation, % min.: 120 (MSRVS and MSRS) / 100 (MSRF and MSRVF); ASTM D3574, Test E
- Compression Set, % max. @ 70°C (158°F): 10; ASTM D3574, Test D
- Density, kg/m³ (lb/ft³): 15 (240) all grades; ASTM D3574-95, Test A
- Recommended Constant Use Temperature (Max.): 70°C (158°F); ASTM D746-98
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Density, kg/m³ (lb/ft³) | 15 (240) all grades | ASTM D3574-95, Test A |
| Specific Gravity | 0.24 all grades | — |
| Density Tolerance, % | ± 10 | — |
| Standard Thickness | See Product Availability | — |
| Thickness Tolerance, % | ± 10 | — |
| Standard Width, mm (inches) | 1372 (54) | — |
| Standard Color (Code) — MSRVS Very Soft | Sea Mist (73) | — |
| Standard Color (Code) — MSRS Soft | Light Jade (71) | — |
| Standard Color (Code) — MSRF Firm | Patina (79) | — |
| Standard Color (Code) — MSRVF Very Firm | Dark Jade (80) | — |
| Air Permeability | Open-Cell – Breathable | Gurley Densometer |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection, psi (kPa) — MSRVS Very Soft | 0.3–3.5 (2–24) | 0.2″/min. Strain Rate, Force @ 25% Deflection |
| Compression Force Deflection, psi (kPa) — MSRS Soft | 1.5–6.5 (10–45) | 0.2″/min. Strain Rate, Force @ 25% Deflection |
| Compression Force Deflection, psi (kPa) — MSRF Firm | 3–18 (21–124) | 0.2″/min. Strain Rate, Force @ 25% Deflection |
| Compression Force Deflection, psi (kPa) — MSRVF Very Firm | 4–22 (27–151) | 0.2″/min. Strain Rate, Force @ 25% Deflection |
| Compression Set, % max. @ 70°C (158°F) | 10 | ASTM D3574, Test D |
| Hardness, Durometer Shore O — MSRVS | 12 | — |
| Hardness, Durometer Shore O — MSRS | 18 | — |
| Hardness, Durometer Shore O — MSRF | 22 | — |
| Hardness, Durometer Shore O — MSRVF | 30 | — |
| Resilience, Shore Instrument Resiliometer avg. — MSRVS | 4 | ASTM D2632-92, Vertical Rebound |
| Resilience, Shore Instrument Resiliometer avg. — MSRS | 4 | ASTM D2632-92, Vertical Rebound |
| Resilience, Shore Instrument Resiliometer avg. — MSRF | 7 | ASTM D2632-92, Vertical Rebound |
| Resilience, Shore Instrument Resiliometer avg. — MSRVF | 8 | ASTM D2632-92, Vertical Rebound |
| Tear Strength, pli min. (kN/m) — MSRVS | 4 (0.7) | ASTM D624 Die C |
| Tear Strength, pli min. (kN/m) — MSRS | 5 (0.9) | ASTM D624 Die C |
| Tear Strength, pli min. (kN/m) — MSRF | 10 (1.7) | ASTM D624 Die C |
| Tear Strength, pli min. (kN/m) — MSRVF | 12 (2.1) | ASTM D624 Die C |
| Tensile Elongation, % min. — MSRVS and MSRS | 120 | ASTM D3574, Test E |
| Tensile Elongation, % min. — MSRF and MSRVF | 100 | ASTM D3574, Test E |
| Tensile Strength, psi min. (kPa) — MSRVS | 15 (104) | ASTM D3574, Test E |
| Tensile Strength, psi min. (kPa) — MSRS | 40 (276) | ASTM D3574, Test E |
| Tensile Strength, psi min. (kPa) — MSRF | 80 (552) | ASTM D3574, Test E |
| Tensile Strength, psi min. (kPa) — MSRVF | 100 (689) | ASTM D3574, Test E |
Environmental & Biocompatibility
| Property | Value | Test Method |
| Water Vapor Transfer, Typical g/m²/24hrs (g/ft²/24hrs) | 400 (> 37) | Based on ASTM E96-00 |
| Water Absorption, Typical % Weight Gain | < 30% | Based on ASTM D570 |
| Hydrolysis Resistance, Compression Set, % max. | Good Resistance / 5 | ASTM D3574 Test J / Test D after autoclaved 5 hrs @ 121°C (250°F) |
| Antimicrobial, Fungal Resistance | Does not promote fungal growth | ASTM G21 |
| Skin Contact — Primary Skin Irritation | Pass | ISO 10993-10, 2010 |
Thermal Properties
| Property | Value | Test Method |
| Recommended Constant Use, max. | 70°C (158°F) | ASTM D746-98 |
| Recommended Intermittent Use, max. | 121°C (250°F) | — |
- Orthotic and prosthetic slow-recovery padding where viscoelastic memory response is required for pressure redistribution
- Pressure-relief insoles and foot orthotics requiring gradual recovery after each step cycle
- Wearable device comfort layers where slow rebound reduces impact transmission at skin interfaces
- Skin-contact cushioning requiring memory response in seating and positioning medical devices
- Protective equipment liners requiring progressive energy absorption across four firmness grades
Common industries: medical devices, orthotics and prosthetics, wearable technology, protective equipment.
PORON Medical® Slow Recovery Urethanes are open-cell, breathable polyurethane foams that exhibit a viscoelastic (memory foam) response, returning slowly to their original shape after compression.
Four color-coded firmness grades are available — Very Soft (MSRVS, Sea Mist / 73), Soft (MSRS, Light Jade / 71), Firm (MSRF, Patina / 79), and Very Firm (MSRVF, Dark Jade / 80) — all sharing the same density of 240 kg/m³ (15 lb/ft³) and a standard width of 1372 mm (54 in). The slow-recovery characteristic is quantified by resilience (vertical rebound) values of 4–8 across the four grades, distinguishing them from standard resilient PORON grades.
Shore O hardness ranges from 12 (Very Soft) to 30 (Very Firm).
All four grades pass ISO 10993-10:2010 primary skin irritation and do not promote fungal growth per ASTM G21. Hydrolysis resistance is good, with a maximum compression set of 5% after autoclaving 5 hrs @ 121°C (250°F), supporting autoclave compatibility. Water vapor transfer is 400 g/m²/24hrs (> 37 g/ft²/24hrs) typical — notably higher than standard PORON Medical grades. Water absorption is less than 30% weight gain typical.
PORON® Urethanes are unaffected by mild organic acids and bases; they show modest swelling with oils, greases, and other linear hydrocarbons. Strongly polar solvents will greatly swell PORON Urethanes; in most cases, physical properties recover to a great extent as the solvents evaporate.
What differentiates PORON Medical® Slow Recovery from standard PORON Medical® grades?
PORON Medical® Slow Recovery grades exhibit a viscoelastic (memory foam) response, returning slowly to their original shape after compression. This is quantified by resilience (vertical rebound) values of 4–8 — significantly lower than standard PORON Medical grades — and makes these materials suited for pressure-relief and load-redistribution applications where rapid spring-back would be counterproductive.
Why is compression set critical for a slow-recovery medical foam?
Compression set measures how much permanent deformation occurs after sustained loading at temperature. All Slow Recovery grades achieve a maximum compression set of 10% at 70°C (158°F) and 5% maximum after autoclave exposure at 121°C (250°F), ensuring the foam retains its original thickness and continues to provide consistent pressure redistribution and comfort over the service life of the orthotic or device.
What is the service temperature range for PORON Medical® Slow Recovery grades?
Recommended constant use temperature is 70°C (158°F) maximum per ASTM D746-98 — lower than standard PORON Medical grades — with intermittent use to 121°C (250°F). The material is autoclave compatible at 5 hrs @ 121°C (250°F).
Are PORON Medical® Slow Recovery grades suitable for skin-contact medical environments?
Yes. All four grades pass ISO 10993-10:2010 primary skin irritation testing and do not promote fungal growth per ASTM G21. The material is hydrolysis resistant and autoclave compatible. No additional regulatory compliance standards are specified on the manufacturer's TDS.
How should PORON Medical® Slow Recovery grades be specified?
Specify grade (PORON Medical® Slow Recovery), firmness sub-grade (MSRVS, MSRS, MSRF, or MSRVF), thickness, color, compliance requirements, dimensional tolerances, and finished format.
