This article concentrates on the difference between closed and open cell Foam padding, the formulation of Rubber Foams, the properties and primary characteristics of closed and open cell Foams and their applications.

What is the difference between open and closed cell?

Open cell is made up of a series of inter-connecting cells with an open structure, allowing for the elastic properties of the cells. When compressed, cells squash together tightly in any direction, and when compression is released, the air intake allows the padding to return to its original state quickly. Open cells are less likely to be broken, resulting superior performance when used over time. Open cells are typically less dense than their closed cell counterparts, although depending on the application, the composition of the padding can be altered to increase density.

Closed cell is made up of a series of enclosed air pockets, comparable to small balloons or Rubber balls compacted within a Rubber membrane. When compressed, air is released through the cell walls and the air pockets are squashed down to small disc shapes. When compression is released, air enters back through the cell walls at a slower rate than open cells. Closed cells tend to be stiffer or more rigid due to this giving them superior resistance to moisture, ideal for use in damp applications such as gasketing and insulation. Similar to open cell padding, closed cell composition can be altered to amend its density, rigidity, compression resistance and more.

How are Rubber Foams formulated?

Rubber Foams are produced by a process of sheeting, moulding and extrusion from compounded gum Rubber and formulated using a number of raw ingredients including chemicals, liquid polymers such as polyol and polyisocyanates, additives which act as catalysts to increase production speed and blowing agents to create gas bubbles during Foam formulation. Surfactants such as silicone or polyethers are also used to control the size of the bubbles. The physical properties of Rubber Foams are dependent on the alloy composition and reaction temperature at the production stage. This will be determined by the application of the end product and the characteristics and qualities of the product can be manipulated to suit individual requirements.

Properties and primary characteristics of open and closed cell Foams

Property/ Primary characteristicOpen cell FoamsClosed cell Foams
ComfortSofter and less rigidStiffer and firmer to touch
DurabilityLess durable, application dependentMore durable, application dependent
WeightTypically 0.5lb per cubic foot, formulation
Typically 2lb per cubic foot, formulation
Compression resistanceMore compressiveLess compressive
DensityTends to be higherTends to be lower
Recovery and reboundDraws air back in faster so returns to original
state quicker
Slower to return to original state
Quality of performanceDependent on applicationSuperior air sealing benefits for use in
application such as insulation.
Heat transferHigher thermal conductivityLower thermal conductivity
Moisture transferLess resistant to moistureSuperior water resistance


Automotive seating and cushioning – both closed and open cell Foams can be used for seating, depending on the formulation of the Foam at the manufacturing stage, however, open cell Foams are known for their comfort, rebound and recovery characteristics.

  • HVAC Gaskets and Insulation – closed cell Foams are often chosen for gasketing and insulation applications due to their water-resistant properties.
  • Seals and wrapping – due to its density, rigidity, durability and performance, closed cell Foams are the most common choice for pipe wrapping and sealing applications in the construction industry.
  • Soundproofing – open cells are most effective in soundproofing small spaces.
  • Interior applications – open cell Foams are more common in interior applications such as roofing and wall lining.
  • Exterior applications – closed cell Foam padding is commonly used in exterior applications due to its resistance to heat and water.
  • Sound insulation – closed cell Foams are ideal in sound insulation applications such as microphones or amplifiers due to their resilience to vibration.

Types of elastomeric Foams

Alanto specialises not only in manufacturing the highest quality in open and closed cell Foam formulations, but in ensuring that we supply the most effective solution for your unique application.

Please be aware that this article should be used as a guide only. For a tailored solution or to find out more about the best Foam for your needs, send us an enquiry and we’ll be more than happy to help.