Closed Cell v Open Cell

Closed Cell Foam and Open Cell Foam

Foam structures consist of a flexible material that is filled with voids, or bubbles. Two of the primary categories of foam are open cell foam and closed cell foam.

Foams are generated by forming gas bubbles in a liquid base which then begins to set over a short period of time, and the properties of the liquid and gas determines the final foam structure.

The distinction between Closed Cell and Open Cell Foam

  • Closed cell foam - the bubbles are completely encompassed within the liquid and when it sets, the gases are entirely fixed within each individual bubble, creating a structure that is impervious.
  • Open cell foam - the bubbles burst during the foaming process to create and interconnection cellular network. This gives rise to softer and breathable foams.
  • Semi-Open Cell foam – this is created by physically bursting the closed cells to create a more open cell product which is softer and easier to compress.


Closed Cell Foam

The need for Closed Cell Foams

Every manufacturing technique has a tolerance, and as such when parts are assembled there are gaps which become part of the final product . Since a closed cell foam is impervious to gases or liquids, it is an ideal medium to use to plug these gaps. Closed cell foams can be used to prevent water or air from passing from one area to another and so they are an ideal medium for plugging the gaps.

The gases within bubbles can’t escape, and so if a heavy weight is dropped on a closed cell foam, the gases are compressed initially, but want to recover, which makes a closed cell foam ideal as a shock absorber.

Actual foam selection, is determined by the end use and environment where it is to be used.

Typical Applications:

  • Seals & Gaskets
  • Packaging
  • Joint fillers
  • Impact Protection products
  • Thermal Insulation
  • Extrusions for edge protector foam, pipe insulation foam or backer rod foam
Closed Cell Foam

Types of Closed Cell Foam or Sponge


Open Cell Foam

The need for Open Cell Foams

Open cell foams are generally soft and compressible and act as good insulators by trapping air within the cells though do allow water and air to pass through.

These foams are particularly good where a lightweight and soft product is required. The modification of the chemistry in the likes of Polyurethane foam, creates a whole host of different properties, such as improvements in the physical properties. So a much wider scope is possible with the developments of PU foam.

Open Cell Foam

Typical Applications:

  • Seating
  • Household sponges
  • Automotive trim
  • Filters
  • Acoustic applications
  • Packaging
  • There are many more

Types of Open Cell Foams

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