Gasket material

Closed-Cell Sponge Rubber Gasket Material

Closed-cell sponge is expanded rubber whose cells do not connect, so it seals against water, dust and air at low bolt load. It is the enclosure, lid and panel gasket sheet: neoprene, EPDM, nitrile and neoprene/EPDM/SBR blends, graded under ASTM D1056, and cut to your drawing on our waterjet.

Request a quote in Closed-Cell Sponge RubberAll gasket materials
Family
Cellular rubber, closed cell
Temperature
-40 C to 93 C (-40 F to 200 F), blended sponge
Thickness
1/16 in to 2 in
Formats
Rolls 42 in and 54 in wide; sheets 39 x 78 in, on the cited listings
Designations
ASTM D1056 Type 2 grades, e.g. 2A1
Product
Sheet gaskets waterjet-cut to your drawing in Orange, California

Figures are the cited maker or standards values; the sheet datasheet and your application govern the final choice.

Every common gasket sheet material is quick for us to source, and we cut it to your print on our waterjet.

What closed-cell sponge seals

Closed-cell sponge compresses easily and springs back, so it takes up gaps between stamped covers, doors, lids and panels that a solid sheet would bridge only under heavy bolting. Because the cells are sealed, the sheet does not wick water the way open-cell foam does. That makes it the usual choice for weather seals, dust seals, vibration pads and enclosure gaskets where the load is a latch or a few screws, not a flange.

Read the ASTM D1056 callout on the print before you pick a sheet. The first digit is the cell type, the letter is the polymer class, and the last digit is the firmness grade [S3]. A print that says 2C2 wants closed-cell neoprene at 5 to 9 psi compression deflection; a 2A1 wants a soft EPDM or blended sponge.

Neoprene, EPDM or blend

Neoprene sponge (class C) tolerates moderate oil and weather. EPDM sponge (class A) is the outdoor and ozone choice where no oil is present, and the blended neoprene/EPDM/SBR sheet is the general-purpose enclosure gasket that carries most of the UL listings [S4]. Nitrile sponge (class B) is the one to name when the gasket sees oil mist or fuel vapor. For high or low temperature, silicone sponge (class D) takes over.

Specifications

Closed-Cell Sponge Rubber specifications

Values as published by the cited sources; [Sn] refers to the source list below
PropertyValue (in / mm, C / F as stated)Source
Cell structureClosed cell (ASTM D1056 Type 2); open cell is Type 1[S3, S1]
Class (polymer family)A: not oil resistant (EPDM or SBR); B: oil resistant, low swell (nitrile); C: oil resistant, medium swell (neoprene); D: extreme temperature (silicone)[S3]
FirmnessD1056 grade by compression deflection at 25 percent: grade 1 = 2 to 5 psi, grade 2 = 5 to 9 psi, grade 3 = 9 to 13 psi, grade 4 = 13 to 17 psi, grade 5 = 17 to 25 psi[S3]
Example gradeNeoprene/EPDM/SBR blend, ASTM D1056 2A1: density 6 plus or minus 2 pcf, compression deflection 3.5 plus or minus 1.5 psi[S5]
Temperature, blended sponge-40 C to 93 C (-40 F to 200 F); 121 C (250 F) intermittent[S4, S5]
Temperature, EPDM sponge-40 C to 93 C (-40 F to 200 F)[S6]
Thickness1/16 in to 2 in (1.6 mm to 51 mm), blended sponge; 1/16 in to 1 in, EPDM sponge sheet[S4, S6]
FormatsRolls 42 in and 54 in wide, slit as narrow as 1/4 in; sheets 39 x 78 in, on the cited listings[S4, S6]
DesignationsASTM D1056 type, class and grade (for example 2A1, 2C2); the standard itself lists Types 1 and 2, Classes A to D, Grades 0 to 5[S1, S3]

How we cut it

Gaskets are waterjet-cut to your drawing in Orange, California. Send a DXF, DWG or PDF with the thickness, the material or the specification callout, and the quantity. There is no die to build, so a single prototype and a repeat run go through the same setup, and a revision needs only a new file. The sheet comes from the sheet makers we buy from, to the callout on your print; the cutting is ours. Thick sponge is where the waterjet earns its place: a steel-rule die pinches soft cellular sheet and leaves a concave edge, while the jet leaves the edge square. Adhesive-backed sponge is cut with the liner on.

Where Closed-Cell Sponge Rubber is used, and the usual alternatives

The print or the sheet datasheet governs; these are the sheets usually specified instead:

  • Solid neoprene: when the gasket carries a bolted flange load and needs to hold pressure.
  • Silicone sponge: when the enclosure runs hot or cold beyond what neoprene and EPDM sponge tolerate.
  • PORON® foam: when a thin, low-compression-set pad is wanted for electronics or displays.
  • Adhesive backing: when the gasket must stay put on a door or lid during assembly.

Related gasket materials: Neoprene Gasket Material, Silicone Sponge Gasket Material, PORON Polyurethane Foam Gasket Material, Adhesive-Backed (PSA, Peel-and-Stick) Gasket Material. The full index is on the gaskets hub; send the drawing through request a quote.

Frequently asked

What is the difference between closed-cell sponge and foam?

Trade use is loose. In ASTM D1056, sponge or expanded rubber is the material, and Type 2 means closed cell. Open-cell foam soaks up water and is cut dry; closed-cell sponge does not and goes on the waterjet.

How do I read a D1056 callout like 2C2?

Type 2 is closed cell, class C is neoprene (oil resistant, medium swell), and grade 2 is a compression deflection of 5 to 9 psi at 25 percent. State the callout on the print and the sheet is matched to it.

Can you cut sponge with adhesive on one side?

Yes. Adhesive-backed sponge is cut with the release liner on, so the part arrives ready to peel and place. Say which face gets the adhesive.

How thick can a sponge gasket be?

Blended closed-cell sponge is sold from 1/16 in to 2 in thick; waterjet cutting typically handles sponge to 2 in, an industry figure rather than a Conquest machine spec, and the thickness is confirmed on the quote. Thick sponge cuts cleaner on the waterjet than under a die.

Does closed-cell sponge hold pressure?

Not much. Sponge seals against weather, dust and low-pressure air at light bolt load. A flange with pressure behind it wants solid sheet.

Sources

  1. [S1] ASTM D1056-20, Standard Specification for Flexible Cellular Materials: Sponge or Expanded Rubber, https://store.astm.org/d1056-20.html, accessed 2026-09-13.
  2. [S2] ASTM F104-11(2020), Standard Classification System for Nonmetallic Gasket Materials, https://store.astm.org/f0104-11r20.html, accessed 2026-09-13.
  3. [S3] ASTM D1056 summary (type, class and grade table), Atlantic Gasket Corporation, https://www.atlanticgasket.com/ASTM-D-1056-information.html, accessed 2026-09-13.
  4. [S4] Neoprene/EPDM/SBR Closed Cell Sponge Rubber, Gasket Supply, https://www.gasketsupply.com/pages/neoprene-epdm-sbr-closed-cell-sponge-rubber, accessed 2026-09-13.
  5. [S5] Style SCE41B Closed Cell Neoprene/EPDM/SBR Sponge, Atlantic Gasket Corporation, https://www.atlanticgasket.com/materials/spec-sheets/style-sce41b-closed-cell-sponge.html, accessed 2026-09-13.
  6. [S6] Foam Sponge Rubber (closed-cell blend and EPDM sheets), Rubber-Cal, https://www.rubbercal.com/closed-cell-rubber-blend.html, accessed 2026-09-13.

PORON is a trademark of Rogers Corporation. No affiliation or endorsement is implied.

Related guides

O-Ring Temperature Ranges by MaterialO-Ring Chemical Compatibility GuideWhich O-Ring Durometer (Shore A Hardness) to Pick

Send the Closed-Cell Sponge Rubber gasket drawing and the quantity

Upload a DXF, DWG or PDF of the gasket with the quote request, or a photo of the part with a ruler if no drawing exists. Add the sheet thickness, the durometer or grade, the quantity and whether adhesive backing is wanted. Gaskets are cut in our own shop in Orange, California; a Conquest representative replies.

Request a quote

Last updated

Request a quote