4# Polyester Polyurethane Foam
H-O Products 4# Polyester Polyurethane Foam is an open cell, medium density polyester polyurethane foam with a density of 4 lb/ft³ ±10% and a compression force deflection of 0.65 psi average at 25% per ASTM D3574. It is described as a medium firm foam rated for FMVSS-302, UL 94 HF-1 (at 0.12″ minimum thickness), REACH, and RoHS compliance. It is suited to acoustical sound absorption and air dam foam and pad applications.
Key Properties
- Compression Force Deflection @ 25%, Average: 0.65 psi (ASTM D3574)
- Tensile Strength (Average): 20 psi (ASTM D3574)
- Elongation (Average): 215% (ASTM D3574)
- Density: 4 lb/ft³ ±10% (ASTM D3574)
- UL 94 HF-1: Pass (at 0.12″ minimum thickness)
- FMVSS-302: Pass
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Thickness | 1/8″, 3/16″, 1/4″, 3/8″, 1/2″, 3/4″, 1″ | — |
| Color | Charcoal Gray | — |
| Material/Substrate | Polyester Polyurethane Foam | — |
| Cell Structure | Open Cell | — |
| Density | 4 lb/ft³ ±10% | ASTM D3574 |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection @ 25%, Average | 0.65 psi | ASTM D3574 |
| Compression Force Deflection @ 25%, Minimum | 0.55 psi | ASTM D3574 |
| Compression Force Deflection @ 50%, Average | 0.85 psi | ASTM D3574 |
| Compression Force Deflection @ 50%, Minimum | 0.65 psi | ASTM D3574 |
| Tensile Strength (Minimum) | 12 psi | ASTM D3574 |
| Tensile Strength (Average) | 20 psi | ASTM D3574 |
| Elongation (Minimum) | 120% | ASTM D3574 |
| Elongation (Average) | 215% | ASTM D3574 |
Flame & Fire Performance
| Property | Value | Test Method |
| Flame Retardant | Flame retardant by special request | — |
| FMVSS-302 | Pass | — |
| UL 94 HF-1 | Pass | — |
Regulatory / Compliance Data
| Property | Value | Test Method |
| REACH | Pass | — |
| RoHS | Pass | — |
Aging Performance
Dry Heat Aging
| Property | Value | Test Method |
| Retention of Tensile Strength After 22 Hours, 140°C, Dry Heat Aging | Min. 70% | ASTM D3574 |
Steam Autoclave
| Property | Value | Test Method |
| Retention of Tensile Strength After 3 Hours, 105°C, Steam Autoclave | Min. 70% | ASTM D3574 |
Compliance
- FMVSS-302 — Compliant
- UL 94 HF-1 — Compliant (at 0.12″ minimum thickness)
- REACH — Compliant
- RoHS — Compliant
- Acoustical and sound absorbing foam components in automotive, HVAC, and enclosure assemblies where a medium firm open cell polyester foam is specified
- Air dam foam and pads in automotive and electronic assemblies requiring moderate compression resistance and reliable dimensional recovery
- Die-cut or clicked foam components for high-volume production where medium density and broad thickness availability are required
- Automotive interior and underhood acoustic insulation components requiring FMVSS-302 and UL 94 HF-1 compliance at 0.12″ minimum thickness
- Sound damping pads and baffles in consumer electronics and appliance assemblies
Common industries: automotive, HVAC, acoustics, consumer goods, electronics.
The 4# Polyester Polyurethane Foam is the mid-density grade in H-O Products’ polyester polyurethane foam series, at 4 lb/ft³ ±10%, and is described as a medium firm open cell foam. It is designed for acoustical sound absorption and air dam foam and pad applications where a moderate compression resistance is required. The material can be easily die-cut into any shape and is clickable, supporting high-volume converted part production.
Tensile strength is 12 psi minimum and 20 psi average per ASTM D3574. Elongation is 120% minimum and 215% average — the highest average elongation in the series. Retention of tensile strength after 22 hours at 140°C dry heat aging is a minimum of 70%, and after 3 hours at 105°C steam autoclave is a minimum of 70%, both per ASTM D3574. The material passes FMVSS-302, UL 94 HF-1 (at 0.12″ minimum thickness), REACH, and RoHS. A flame retardant formulation is available by special request.
Compliant with FMVSS-302, UL 94 HF-1 (at 0.12″ minimum thickness), REACH, and RoHS.
What differentiates the 4# Polyester Polyurethane Foam from the lower-density 2# and higher-density 6# grades?
The 4# is the mid-density grade at 4 lb/ft³ with a CFD of 0.65 psi average at 25% — lower than both the 2# (0.75 psi) and 6# (0.75 psi) at that deflection level. It delivers the highest average elongation in the series at 215%, indicating greater flexibility and stretch capacity than either adjacent grade. It meets UL 94 HF-1 at 0.12" minimum thickness, the same as the 6# but a thicker requirement than the 2#'s 0.06".
Why does compression force deflection matter for open cell polyurethane foam selection?
Compression force deflection (CFD) defines the load required to compress the foam to a given deflection level, which determines how much resistance the foam provides in a seal, cushioning, or air dam application. The 4# grade has an average CFD of 0.65 psi at 25% — the lowest in the series — reflecting its medium firm character. This positions it for applications where moderate, consistent compression resistance is needed without the higher resistance of the denser 6# grade.
What is the service temperature range for the 4# Polyester Polyurethane Foam?
A specific service temperature range is not stated on the manufacturer's TDS for this material. Aging performance data includes retention of tensile strength after 22 hours at 140°C dry heat aging and after 3 hours at 105°C steam autoclave, both with a minimum retention of 70%.
Is the 4# Polyester Polyurethane Foam suitable for regulated environments?
Yes. The material passes FMVSS-302, UL 94 HF-1 (at 0.12" minimum thickness), REACH, and RoHS, as stated on the TDS. A flame retardant formulation is also available by special request.
How should the 4# Polyester Polyurethane Foam be specified?
Specify grade (4# Polyester Polyurethane Foam), thickness, compliance requirements (FMVSS-302, UL 94 HF-1 minimum thickness if applicable, REACH, RoHS), dimensional tolerances, and finished format.
