Open Cell vs Closed Cell Foam: Which is Better for Backpacks?

The Lab,  
Taylor Coil

Foam is a varied and versatile thing, ranging from the ultra-squishy stuff of mattresses to the dense, durable soles of running shoes. It can be millimeters thin or inches thick, rigid or soft, springy or squishy. It can be injection-molded, which is a 3D shaping method, or die-cut, which is like a giant cookie cutter.

Perhaps the most noticeable difference between foams, however, is whether they’re open-cell or closed-cell.

Open-Cell Foam


Think of a sponge when you picture open-cell foam — the holes that give open-cell foam its squish go all of the way to the edges of the material for a swiss cheese look. Open-cell foam is known for “spring,” immediately returning to its shape when you press it down. Picture those mattress toppers that were popular in the 90s — the ones that look like egg crates. Remember how squishy and springy they felt? They’re a classic example of open-cell foam.

The downside of open-cell foam: it’s not as durable as closed-cell foam. Eventually, it will flatten out, which is a problem for a backpack’s shoulder straps if not used in tandem with closed-cell foam.

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Closed-Cell Foam


When you picture closed-cell foam, picture the dense, slightly squishy stuff found in the bottom of running shoes. It looks solid from the outside — there are holes inside that make the material springy, but you can’t see them from the outside because they don’t go all the way to the edge. Closed-cell foam is a slightly rigid, highly durable type of foam that breaks in over time to get even more comfortable. It’s not springy like open-cell foam and won’t flatten over time, but it’s also not as cushy.

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Ariaprene is a brand of premium closed-cell foam. It’s incredibly soft and comfortable, and moves with your body without needing to break it in — kind of like an environmentally-friendly version of the stuff used in wetsuits. Ariaprene is an ideal use of closed-cell foam’s durability without sacrificing comfort, softness, and squish. Best of all, Ariaprene incorporates innovative fabric technology to provide hypoallergenic, sweat-wicking, and quick-drying properties.

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