Open Cell vs. Closed Cell Foam: A Buyer's Guide for Industrial Die Cutting
Whether you're specifying a foam gasket for an HVAC enclosure, a cushioning insert for industrial packaging, or a vibration isolation pad for equipment, the single most consequential decision you'll make is foam cell structure. Open cell and closed cell foams behave differently in almost every performance dimension that matters to a design engineer -- compression, moisture, temperature, acoustic absorption, and long-term seating. Getting it right at the spec stage is far less expensive than correcting it after tooling.
This guide covers the core differences, common material types within each category, and the industrial applications where each performs best.
What Cell Structure Actually Means
Foam is made by introducing gas into a polymer matrix during manufacturing. In open cell foam, the gas bubbles break through their cell walls during processing, creating an interconnected porous structure. In closed cell foam, each bubble remains intact and sealed.
That structural difference drives nearly every performance characteristic downstream:
Open cell foam – soft, compressible, breathable, and acoustically absorptive. Because the cells are connected, air and moisture can pass through.
Closed cell foam – firmer, more dimensionally stable, moisture-resistant, and better at blocking rather than absorbing sound. Each sealed cell traps a small volume of gas, which gives closed cell foam its buoyancy and insulating properties.
Open Cell Foam: Material Types and Best Applications
Open cell foams are the right choice when your application needs compliance, acoustic absorption, or air/moisture permeability:
Polyurethane (PU) foam – The most widely used open cell foam in industrial applications. Available across a wide density range; softer grades are used for cushioning and sound absorption, higher-density grades for filtration and technical seating applications.
Reticulated polyurethane – A highly open, skeletal foam used in filtration, liquid absorption, and acoustic baffling. Very low density and high airflow -- often specified in HVAC and industrial equipment applications.
Common industrial applications for open cell foam:
HVAC and equipment acoustics – lining panels and enclosures where sound absorption, not blocking, is the goal
Filtration media – air and liquid filtration elements that require high airflow through the foam
Protective packaging inserts – cushioning for instruments, electronics, and components where controlled compression is needed
Seating and operator interfaces – comfort pads, handle grips, and ergonomic applications
Note: Open cell foam should not be used in applications with water exposure or where compression set matters -- the interconnected cells will hold moisture and the foam will not recover fully after sustained load.
Closed Cell Foam: Material Types and Best Applications
Closed cell foams are the right choice when your application demands moisture resistance, consistent sealing force, thermal insulation, or long-term dimensional stability:
Polyethylene (PE) foam – Lightweight, chemically resistant, and available in cross-linked and non-cross-linked grades. Cross-linked PE (XLPE) is stiffer and more durable; commonly used in protective packaging, automotive liners, and vibration isolation.
EVA (Ethylene Vinyl Acetate) – Closed cell foam with better mechanical properties than PE -- higher tear strength, better compression set recovery, and broader temperature tolerance. Used in gasketing, footwear, marine, and specialty packaging applications.
EPDM foam – Closed cell rubber-based foam with excellent weather, UV, and ozone resistance. The standard for outdoor sealing applications, HVAC gaskets, and anywhere the foam will see temperature cycling.
Neoprene foam – Closed cell with good chemical resistance and moderate temperature performance. Used in industrial seals, vibration dampening mounts, and aerospace applications.
Silicone foam – Closed cell with the broadest operating temperature range (-65F to 400F+). Specified in high-temperature sealing, electrical enclosures, and medical device applications where other foams fail.
Common industrial applications for closed cell foam:
Gaskets and enclosure seals – HVAC units, electrical enclosures, appliance housings, and industrial equipment panels
Thermal insulation – anywhere heat transfer through the foam is a concern -- pipe insulation, refrigeration, and equipment panels
Vibration and shock isolation – equipment mounts, transport packaging, and anti-vibration pads where the foam must return to shape after load
Weather sealing – door and window gasketing, marine applications, and outdoor enclosures
Automotive liners and die cut parts – wheel well liners, trunk liners, and underbody applications where moisture exposure is continuous
Note: Closed cell foam is generally firmer and less acoustically absorptive than open cell. If sound absorption is the primary goal, closed cell is the wrong choice even if it is moisture-resistant.
Choosing Between Open Cell and Closed Cell: A Quick Reference
Sealing against air or water? – Closed cell
Absorbing airborne sound? – Open cell
Blocking sound transmission? – Closed cell (mass matters more than absorption here)
Sustained compression load? – Closed cell (better compression set recovery)
Thermal insulation? – Closed cell
Filtration or airflow through the foam? – Open cell (reticulated)
Moisture or outdoor exposure? – Closed cell
Cushioning for impact protection? – Open cell (PU) for light loads; closed cell PE or EVA for heavier impact
Chemical resistance? – Depends on the specific chemical -- EVA, EPDM, neoprene, and silicone each have distinct profiles
Fabrication Considerations for Die Cut Foam
Both open and closed cell foams can be flatbed die cut into precise shapes. A few considerations that affect supplier selection:
PSA adhesive backing – Both foam types accept pressure-sensitive adhesive backing. In-house lamination from your die cutter means consistent adhesive coverage and eliminates a handling step. Specifying PSA-backed foam that gets cut and laminated by two different vendors introduces registration and delamination risk.
Tolerances – Closed cell foams hold tighter dimensional tolerances than open cell because they compress less during cutting. If your gasket requires a specific seating force, tolerance on the finished part -- not just the blank -- matters.
Thickness and density – Both variables affect compression deflection force (CDF), which determines how much force is required to compress the foam a given percentage. Specify the compression requirements, not just the material type.
Multi-layer construction – Some applications combine open and closed cell layers -- an open cell absorber bonded to a closed cell barrier, for example. Single-source suppliers who can laminate and cut reduce the number of parties involved and the chances of layer misalignment.
Roylco Industrial cuts both open and closed cell foam to custom shapes with PSA lamination and flatbed capacity up to 84". We are ISO 9001:2015 and WBENC certified, and we support programs from prototype through production. Contact us to discuss your application.