TECHNICAL DATASHEET · SPONGE & FOAM RUBBER
Sponge & Foam Rubber Datasheet
Service temperatures, ASTM D1056 designations, density and compression force deflection for the five cellular compounds we mix — EPDM, neoprene, NBR, natural rubber and silicone. Cellular figures differ from the same polymers in solid form; section 03 explains why. No form, no email address required.
Published 16 September 2026 · Updated
| Field | Value |
|---|---|
| Issue | Rev 1 · publication date |
| Applies to | /products/sponge-foam-rubber |
| Governing standard | ASTM D1056 · ASTM D6576 for adhesive-backed |
Sponge Is Not Specified by Durometer
Solid rubber is specified by hardness. Cellular rubber is specified by compression force deflection — the force needed to compress a specimen to 75% of its original thickness — together with density. A durometer pressed into sponge measures the skin and the gas phase together and gives a number that will not reproduce between batches, which is why ASTM D1056 does not use one.
ASTM D1056 identifies a cellular material with a three-character designation — Type, Class, Grade. A closed-cell, medium-oil-resistance material at 62 to 90 kPa compression force deflection is 2C3. Quote the designation and any competent supplier anywhere will know what you mean.
| Character | Value | Means |
|---|---|---|
| Type | 1 | Open cell — cells interconnect. Absorbs water. Used where compliance matters more than sealing |
| Type | 2 | Closed cell — each cell sealed. Resists water ingress. The type most gasket and weatherseal duty needs |
| Class | A | No oil-resistance requirement |
| Class | B | Oil resistance with low mass change |
| Class | C | Oil resistance with medium mass change |
| Class | D | Extreme temperature service; oil resistance not required |
| Grade | Compression force deflection, kPa | psi | Feel |
|---|---|---|---|
| 0 | 0 – 13.8 | 0 – 2 | Very soft |
| 1 | 13.8 – 34.5 | 2 – 5 | Soft |
| 2 | 34.5 – 62.1 | 5 – 9 | Medium soft |
| 3 | 62.1 – 89.6 | 9 – 13 | Medium |
| 4 | 89.6 – 117.2 | 13 – 17 | Firm |
| 5 | 117.2 – 172.4 | 17 – 25 | Very firm |
Five Cellular Compounds
These figures are for cellular grades and they are not the same as the solid-rubber ranges published elsewhere on this site. A sponge has a gas phase running through it, so its service range, recovery and ageing behaviour all differ from the same polymer in solid form. Where the two disagree, the material form decides which applies.
| Compound | Full name | Service temperature | Indicative hardness | Key applications |
|---|---|---|---|---|
| EPDM | Ethylene propylene diene monomer | −50 to +120 °C constant +130 °C intermittent | 20 – 80 Shore A | HVAC gaskets, roofing tape, weatherseals, hot-water systems |
| CR | Chloroprene (neoprene) | −40 to +75 °C constant +90 °C intermittent | 25 – 70 Shore A | Marine seals, refrigerant lines, adhesive tape backing |
| NBR | Nitrile butadiene rubber | −40 to +100 °C constant +120 °C intermittent | 30 – 90 Shore A | Hydraulic seals, oil-resistant gaskets, fuel system foam |
| NR | Natural rubber | −55 to +80 °C constant | 20 – 60 Shore A | Anti-vibration mounts, acoustic panels, packaging foam |
| VMQ | Silicone (vinyl methyl) | −60 to +200 °C constant +230 °C intermittent | 10 – 80 Shore A | Clean-room seals, high-temperature ovens, gasketing |
Not available as sponge
AEM, FKM and SBR are mixed as solid compounds and are not offered in cellular form. If your duty needs a fluoroelastomer or a hot-oil compound in a compressible section, tell us the duty — a solid section at low hardness will often do the job a sponge was specified for.
The Two Numbers That Actually Specify a Sponge
Density governs weight, cost and how much the section recovers after being held compressed. Compression force deflection governs the closing force a gasket needs and how well it seals against an uneven flange. Neither is a property of the polymer — both follow from the grade. Closed-cell EPDM runs 75 to 105 kg/m³ at grade 2A1 and 180 to 200 at 2A2, which is the same compound at twice the density. So specify the D1056 designation and it carries both numbers, and we confirm the measured figures for the exact material on the batch certificate.
| Compound | D1056 Type & Class | Typical density by grade | CFD at 25% | Water absorption |
|---|---|---|---|---|
| EPDM closed cell | Type 2, Class A | 2A1 75–105 kg/m³ 2A2 180–200 kg/m³ | set by grade — see §02 | Low — closed cell |
| CR closed cell | Type 2, Class C | 2C1 115–155 kg/m³ 2C2 140–190 kg/m³ | set by grade — see §02 | Low — closed cell |
| NBR closed cell | Type 2, Class C | quoted per grade | set by grade — see §02 | Low — closed cell |
| NR open cell | Type 1, Class A | quoted per grade | set by grade — see §02 | High — open cell |
| VMQ closed cell | Type 2, Class D | quoted per grade | set by grade — see §02 | Low — closed cell |
Sheet, Roll, Profile and Moulded
| Format | Quoted by | Notes |
|---|---|---|
| Sheet | area | Cut to your development or template. Thickness to your drawing |
| Roll | length | Where the run is continuous and the width is standard |
| Extruded profile | total length | Door, window and cabinet seals. Die cut in-house; tolerances to ISO 3302-1 class E1–E3 |
| Die-cut parts | piece | Gaskets and washers cut from sheet, to your outline |
| Moulded sponge | piece | Where the part has a three-dimensional shape rather than a section |
Thickness, width and length are quoted against the job rather than held as stock sizes. Tell us the section and the quantity and we will confirm what is practical from a single run.
Self-Adhesive Foam Tape
| Core | Temperature | Resistance | Used for |
|---|---|---|---|
| EPDM foam tape | −50 to +120 °C constant | Excellent UV and ozone resistance | Outdoor weatherseals, curtain-wall expansion joints, HVAC flanges |
| CR (neoprene) foam tape | −40 to +75 °C constant | Good oil and flame resistance | Marine hatches, refrigerant pipe wrap, fire-door perimeters |
The adhesive is rated separately from the rubber and it is usually the limiting component. A tape core good to +120 °C on an adhesive rated to +80 °C is an +80 °C part. Tell us the surface it goes onto — painted steel, powder coat, plastic or glass — and the service temperature, and we will confirm the adhesive system with the core.
What We Measure
| Property | Method | Where |
|---|---|---|
| Density | ASTM D1056 | In-house |
| Compression force deflection | ASTM D1056 at 25% | In-house |
| Compression set | ASTM D1056 | In-house |
| Tensile and elongation | ASTM D412 | In-house |
| Water absorption | ASTM D1056 | NABL partner laboratory |
| Ozone resistance | ISO 1431-1 | NABL partner laboratory |
| Dimensional conformity | ISO 3302-1 — class M1–M4 moulded, E1–E3 extruded | In-house |
Material test reports, dimensional inspection sheets and a certificate of conformance ship with every consignment. Batch records are retained per shipment and are available on request under NDA. Sponge is packed uncompressed — a cellular section held compressed in transit does not fully recover.
Certification, and what this document is not
ISO 9001:2015 · Certificate 09111526A
Integral Certification Ltd · Valid to 21 February 2027
Scope: rubber moulded components — quality management, not a product approval
IATF 16949 — upgrade in progress, certification targeted by end 2026
ISO 14001 and ISO 45001 — targeted 2027
| This document does not | Because |
|---|---|
| Certify food contact | Margo holds no FDA 21 CFR 177.2600 or equivalent food-contact approval. Silicone sponge is often specified for food and clean-room duty and this document must not be read as clearing it |
| Certify pharmaceutical use | No USP Class VI approval is held |
| Certify potable water | Approval attaches to a compound formulation held by the compound supplier — WRAS, NSF/ANSI/CAN 61, AS/NZS 4020, KTW-BWGL. Never to “EPDM” and never to us |
| Give a flame rating | FMVSS 302 and UL 94 are certified against a specific construction by a third-party laboratory. We will have it tested on request |
| Predict service life | Ageing depends on the installed compression, the substrate and the environment. The data here ranks materials; it does not forecast a maintenance interval |
Specify It With Us
Send the duty — the gap being sealed, the closing force available, the temperature and the medium — and we will recommend a compound, a cell type and a grade, with the datasheet figures for the exact material we would supply. Our engineering team responds within 48 hours. Sponge spans three commercial models. Sheet and die-cut parts are quoted by area, roll and extruded profile by total length, moulded sponge by piece against the standard bulk minimum. Send the section and the quantity and we will tell you which applies.