HR Foam HR-SS
Hardness band
HR-SS = super-soft / hyper-soft HR
Pick for mattress and pillow top layers and soft back cushions: indentation hardness is low at ~38 kg/m³ while resilience stays high and hysteresis low.
Values for the HR-SS condition
Other HR Foam grades and fills
HR Foam is listed in 9 conditions; see the grade overview at HR Foam.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
HR-SSThis page Super-soft / hyper-soft HR | Pick for mattress and pillow top layers and soft back cushions: indentation hardness is low at ~38 kg/m³ while resilience stays high and hysteresis low. | — | 0.08 | 180 | — |
Low-density HR slabstock, ~32–38 kg/m³ | Choose for cost-sensitive furniture backs, upholstery and packaging cushioning at ~32–38 kg/m³; resilience stays good but load bearing and durability are lower. | — | 0.1 | 150 | — |
Conductive / antistatic HR | Choose the carbon-loaded conductive version for electronic component packaging and ESD workstation pads with controlled surface resistance; tensile strength drops to 0.1 MPa. | — | 0.1 | 110 | — |
Combustion-modified / flame-retardant HR | Choose for public, medical and vehicle cushioning that must meet BS 5852 Crib 5, CAL TB117 or GB 17927 fire requirements; combustion modifiers trim tensile strength to 0.11 MPa. | — | 0.11 | 110 | — |
Medical / antimicrobial-treated HR | Pick for medical mattresses, wheelchair cushions and rehabilitation supports needing low VOC and antimicrobial treatment, and suitable for use with waterproof film. | — | 0.12 | 130 | — |
HR45Default Standard HR slabstock, ~42–48 kg/m³ | Default slabstock for sofa seat cushions, mattress comfort layers and office chair pads at ~42–48 kg/m³, giving the best balance of resilience and durability. | — | 0.13 | 130 | — |
Cold-cure molded HR | Use the cold-cure molded version for automotive seats and headrests with bonded covers: one-shot molding avoids cutting scrap but needs mold temperature and release agent control. | — | 0.14 | 110 | — |
High-density HR slabstock, ~52–58 kg/m³ | Pick for high-end sofas, mattresses and long sitting or lying use, where ~52–58 kg/m³ gives the best sag resistance and fatigue life at higher weight and cost. | — | 0.16 | 120 | — |
High load-bearing / firm HR | Use for heavy-duty seating, truck and bus cushions and mattress support layers, where 60 kg/m³ gives a high support (SAG) factor and strong sag resistance at a firmer feel. | — | 0.17 | 100 | — |
What is HR Foam HR-SS?
HR Foam HR-SS is HR Foam heat treated to HR-SS — pick for mattress and pillow top layers and soft back cushions: indentation hardness is low at ~38 kg/m³ while resilience stays high and hysteresis low. HR Foam HR-SS has a tensile strength of 0.08 MPa (0.0116 ksi), weaker than 100% of polymer grades. Elongation at break is 180% and the elastic modulus is 1×10⁻⁵ GPa (1.45×10⁻⁶ Msi). HR Foam HR-SS has a density of 0.04 g/cm³ (0.0014 lb/in³), lighter than 91% of polymer grades. Its glass-transition temperature is -55°C (-67 °F). HR45 is the default condition FabDigit quotes; HR-SS is available on request or by drawing note.
Advantages
- Forms and bends easily — 96/100, better than 100% of polymer grades
- Easy to machine — 88/100, better than 92% of polymer grades
- Lightweight — 0.04 g/cm³ (0.0014 lb/in³), better than 91% of polymer grades
Limitations
- Low stiffness — 1×10⁻⁵ GPa (1.45×10⁻⁶ Msi), worse than 100% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.022 BTU/hr·ft·°F), worse than 90% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
HR Foam HR-SS properties
Typical room-temperature values for HR Foam HR-SS; 15 are specific to this condition. Other listed values are HR Foam reference data and may not represent this condition. Bars are the position among polymer grades.
Physical2
HR Foam HR-SS has a density of 0.04 g/cm³ (0.0014 lb/in³), lighter than 91% of polymer grades. Its glass-transition temperature is -55°C (-67 °F).
Mechanical8
HR Foam HR-SS has a tensile strength of 0.08 MPa (0.0116 ksi), weaker than 100% of polymer grades. Elongation at break is 180% and the elastic modulus is 1×10⁻⁵ GPa (1.45×10⁻⁶ Msi).
Thermal7
HR Foam HR-SS is rated for continuous service to 95°C (203 °F). It conducts heat at 0.04 W/m·K (0.022 BTU/hr·ft·°F), worse than 90% of polymer grades.
Electrical2
HR Foam HR-SS has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 61% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of HR Foam HR-SS takes about 103 MJ of energy and emits 5 kg of CO₂ — less than 54% of polymer grades. Typical recycled content is 0%.
Manufacturability3
HR Foam HR-SS's machinability is excellent (88/100, better than 92% of polymer grades); weldability fair (40/100); formability excellent (96/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HR Foam HR-SS
Is HR Foam easy to machine?
Cut with band saw, horizontal splitting machine, oscillating knife or CNC contour and profile cutting. Hot-wire cutting is not suitable because PU chars and smokes; keep blades sharp and use extraction to avoid torn edges and dust.
Can HR Foam be welded?
Not weldable; bond with water-based or hot-melt adhesive, flame lamination, or high-frequency welding and sewing when combined with fabric.
Can HR Foam be formed, bent or molded?
Two routes: TDI-based continuous box or vertical slabstock foaming with 24 h cure before cutting (Type R), or MDI cold-cure moulding (Type Q) at 45–70 °C mould temperature with 4–6 min demould. Formulation index and cell-opening control set resilience and compression set.
What surface finishes work on HR Foam?
Can be flame- or adhesive-laminated to fabric and nonwoven, fitted with a waterproof TPU film, and die-cut to shape. Plating and hard paint films are not possible, and the open cells absorb solvent-based adhesives.
HR Foam chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| polyether polyol (high-reactivity, EO-timain polyol, functionality 3, OH value 28–35 mgKOH/g | 40 – 60 | 50 |
| polymer (graft SAN/PHD) polyolprovides load bearing and support factor | 5 – 25 | 12 |
| TDI 80/20 or MDI / TDI-MDI blend isocyanTDI for slabstock, MDI for cold-cure molding; index 95–105 | 28 – 40 | 34 |
| water (blowing agent)reacts with NCO to generate CO₂ for blowing | 2 – 4.5 | 3.2 |
| amine + tin catalysts | 0.2 – 1 | 0.5 |
| silicone surfactant (cell opener type) | 0.3 – 1.5 | 0.8 |
| flame retardant / additives (optional)CMHR grades use intumescent or phosphorus FR and melamine | 0 – 15 | 0 |
HR Foam HR-SS — frequently asked
What is HR Foam HR-SS used for?
HR Foam HR-SS is typically used for furniture and mattress cushioning, automotive seat cushions, molded seating pads and sports padding. In short: high-resilience flexible PU; better fatigue than slabstock; higher support factor.
What is the tensile strength of HR Foam HR-SS?
HR Foam HR-SS has a typical tensile strength of 0.08 MPa (0.0116 ksi) — weaker than 100% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is HR Foam HR-SS easy to machine?
Yes — machinability is rated excellent (88/100, better than 92% of polymer grades). Cut with band saw, horizontal splitting machine, oscillating knife or CNC contour and profile cutting. Hot-wire cutting is not suitable because PU chars and smokes; keep blades sharp and use extraction to avoid torn edges and dust.
Can HR Foam HR-SS be welded?
With care — weldability is rated fair (40/100). Not weldable; bond with water-based or hot-melt adhesive, flame lamination, or high-frequency welding and sewing when combined with fabric.
What surface finishes work on HR Foam HR-SS?
Can be flame- or adhesive-laminated to fabric and nonwoven, fitted with a waterproof TPU film, and die-cut to shape. Plating and hard paint films are not possible, and the open cells absorb solvent-based adhesives.
Can HR Foam HR-SS be formed, bent or molded?
Two routes: TDI-based continuous box or vertical slabstock foaming with 24 h cure before cutting (Type R), or MDI cold-cure moulding (Type Q) at 45–70 °C mould temperature with 4–6 min demould. Formulation index and cell-opening control set resilience and compression set.
What is the maximum service temperature of HR Foam HR-SS?
HR Foam HR-SS is rated for continuous use to about 95°C (203 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM D3574 — Standard Test Methods for Flexible Cellular Materials—Slab, Bonded, and Molded Urethane Foams — ASTM (2017)
- JIS K 6401 Flexible cellular polymeric materials — Polyurethane foam — JSA (2011)
- ISO 2439 Flexible cellular polymeric materials — Determination of hardness (indentation technique) — ISO (2008)
- Cellular Solids: Structure and Properties (Gibson & Ashby) — Cambridge University Press (1997)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- HR slabstock and cold-cure molded foam technical data — FXI / Carpenter / Recticel (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.