What Phylon is
Phylon is ethylene vinyl acetate (EVA) compounded with a blowing agent and a crosslinker, then processed through compression molding rather than open slab foaming or direct injection. In the industry the process is often called CMEVA. The finished part has a closed-cell structure with small, even cells and a smooth molded skin.
How Phylon is made
- Compounding — EVA is mixed with a blowing agent, peroxide cross-linker, activators and pigments, then formed into pellets or sheets.
- Pre-foaming — The compound is expanded into an oversized blank, either in a primary mold or as a cut slab.
- Compression molding — The blank is placed in a shaped mold, heated and compressed.
The foam softens, fills the cavity and takes on the final geometry.
- Cooling and stabilising — The mold is cooled under pressure, which fixes the shape and locks in the cell structure.
- Finishing — Flash is trimmed and parts are often painted on the sidewalls.
The second heat-and-press cycle is what separates Phylon from basic EVA. It refines the cell structure, densifies the skin and allows sculpted sidewalls, flex grooves and precise thickness profiles. The trade-off is a longer, more expensive cycle and higher tooling cost than injection molding.
Cushioning: 8 / 8, Max
Phylon's fine, even cells compress progressively under load, which gives a soft, smooth landing without the patchy feel that coarse foams can have. Because compression molding allows lower densities while keeping the part's shape, brands can push Phylon lighter and softer than many injected EVA parts. Hardness, usually specified in Asker C, is tuned through compound and compression ratio.
Rebound: 4 / 8, Medium
Like all standard EVA, Phylon returns a moderate share of the energy put into it. It feels cushioned and damped rather than springy. Ball rebound testing to ISO 8307 typically places it below ETPU and PEBA-based foams. Higher-rebound EVA blends and supercritical foaming can close part of that gap, but they move the material beyond classic Phylon.
Durability: 4 / 8, Medium
Phylon packs out over time for the same reason EVA does: cell walls fatigue under repeated compression and the midsole takes a permanent set. Compression set testing, for example to ASTM D395, is the best way to compare compounds. A dense, well-formed skin and a tight cell structure help, but Phylon will not match PU or TPU over a long service life. Very soft, low-density Phylon loses its feel fastest.
Where Phylon is used
- Running and training shoes — the standard lightweight midsole across many mid-price models.
- Basketball and court shoes — sculpted sidewalls and pods for cushioning units.
- Lifestyle sneakers — clean molded shapes and crisp sidewall detail for design-led silhouettes.
- Carrier midsoles — a frame that holds softer or more resilient foam inserts in place.
Designing with Phylon
Choose Phylon over injected EVA when shape precision, sidewall detail and consistent density matter, and the budget allows for compression tooling. Choose a higher-rebound foam when energy return is part of the product promise.
- Specify density and hardness together; hardness alone does not describe how the part will feel.
- Use compression ratio as a design tool — more compression gives a firmer, more durable skin.
- Reserve the softest grades for the forefoot or a top layer, with firmer Phylon under the heel.
- Cover high-wear contact zones with rubber; exposed Phylon scuffs and wears quickly.