Closed Cell vs Open Cell Foam Explained

The Fundamental Difference

The distinction between closed-cell and open-cell foam lies in the internal structure. In closed-cell foam, each individual gas bubble is completely sealed — gas cannot move between cells. In open-cell foam, the cell walls are broken, allowing gas and liquid to flow freely through the foam matrix.

Closed Cell EVA Foam

All Atami EVA products are closed-cell. The sealed cell structure delivers several critical properties:

• Waterproof: Zero water permeability — water cannot enter the foam at all
• Antibacterial: No internal moisture = no bacterial growth
• High impact absorption: Compressed gas in sealed cells provides excellent rebound
• Chemical resistance: Oils, acids and alkalis cannot penetrate the foam
• Dimensional stability: Maintains shape over long service life
• CE/RoHS certifiable: Meets EU safety requirements for industrial use

Open Cell Foam

Open-cell foam (typically PU or certain PE grades) has interconnected cells that allow free movement of air and moisture. This structure provides:

• Good acoustic insulation (sound absorbed into cell network)
• Very soft, conforming feel
• Low cost for indoor cushioning applications

However, open-cell foam absorbs water readily, degrades with UV exposure and is not suitable for wet, outdoor or industrial environments.

Which for Industrial Applications?

Summary

For any industrial application involving moisture, outdoor exposure, food contact or CE/RoHS compliance requirements, closed-cell EVA foam is the correct specification. Open-cell foam should only be considered for dry indoor applications where cost is the primary constraint and durability is secondary.