PE, PU, EVA & ESD Foam Explained

Foam is not one material. The four types we cut most often — polyethylene, polyurethane, EVA, and ESD — behave differently under load, feel different in the hand, and cost different amounts. Choosing well means matching the foam to the job, not defaulting to whatever is cheapest or whatever the last supplier used.

Below is a plain guide to each foam, how density changes what it does, and the situations where each one is the right answer. We stock densities from 1.2 to 9.0 lb/ft³, and density matters as much as the polymer itself.

Polyethylene (PE)

PE is a closed-cell foam and the workhorse of protective packaging. Closed cells mean it does not soak up water and it holds a routed cavity crisply, so it locates a product precisely. It resists repeated impacts without collapsing, which makes it the default for medium-weight electronics, tools, and instruments. PE also has a clean, firm feel that reads as premium in a fitted case.

Polyurethane (PU)

PU is an open-cell foam that is softer and more compressible than PE. That softness makes it excellent for delicate, low-mass items and for convoluted (egg-crate) lids that press gently down on a product. It is lighter and typically cheaper per volume, but it recovers more slowly after heavy repeated impacts and is less water-resistant. Reach for PU when the product is fragile and light rather than heavy.

EVA

EVA is a denser, more resilient closed-cell foam with a smooth, high-end surface finish. It is the choice when the insert itself is part of the product experience — premium tool cases, cosmetics kits, and presentation packaging — because it looks and feels like a finished good. It carries load well and holds fine detail in routed cavities, at a higher material cost than PE.

ESD (anti-static)

ESD foam is engineered to safely dissipate static charge, which protects sensitive electronics from electrostatic discharge. It comes in static-dissipative and conductive grades and is usually pink or black so it is easy to identify on the line. Use it whenever bare boards, drives, or static-sensitive components are involved. It is not a general upgrade — it is a requirement for specific products.

Compare the four foams

How density changes the protection

Within any foam type, density controls firmness and how much load the material carries before it bottoms out. Low-density foam (around 1.2 to 1.7 lb/ft³) is soft and best for light products; it deflects easily and returns a gentle cushion. High-density foam (up to 9.0 lb/ft³) resists compression and supports heavy items without collapsing under repeated handling. The right density spreads the product’s weight over enough foam that peak impact stays below the product’s failure threshold. Too soft and a heavy item bottoms out onto the box; too firm and a light item gets a harsh, unforgiving stop.

Keep reading

Choosing between foam and paper first? Start with Foam vs. Cardboard Inserts: How to Choose. To see how density and thickness get set against a real drop, read How We Spec Cushioning for Drop Tests. For ESD specifically, see ESD Foam for Electronics. Full material options live on our products page.