Soling and Midsoles

High-Density Rebonded Polyurethane Foam: Rebonded foam is widely used as a structural layer in footwear that requires high load-bearing capacity. Produced from bonded polyurethane foam particles, it is typically available in density ranges from 60 to 150 kg/m³, with common thicknesses between 6 mm and 25 mm.
Its primary function is to provide dimensional stability and resistance to permanent compression. Because of its firmness and durability, rebonded foam is frequently used in safety shoes, work boots, leather footwear, and footwear designed for heavier users. It is also commonly applied as a base layer in orthopedic or medical footwear where long-term support is required.
EVA Foam (Ethylene-Vinyl Acetate): EVA foam is one of the most commonly used materials in athletic and casual footwear midsoles. Typically produced in 25–60 kg/m³ density ranges and 10–35 mm thicknesses, EVA is valued for its lightweight nature and ability to absorb impact while remaining flexible.
EVA offers good energy return and cushioning but may experience compression set over time in heavy-duty or high-load applications. As a result, it is most suitable for running shoes, sports footwear, casual shoes, and applications where reduced weight and flexibility are prioritized.
Closed-Cell Polyurethane (PU) Foam: Closed-cell PU foam is selected for applications that require greater durability than EVA. With densities generally ranging from 45 to 90 kg/m³ and thicknesses between 8 mm and 30 mm, this material provides strong resistance to moisture, oils, and mechanical fatigue.
Because it maintains its shape under sustained load, closed-cell PU foam is commonly used in work boots, hiking footwear, safety shoes, and military or industrial applications where footwear is exposed to demanding environments.
Multi-Layer and Hybrid Midsole Constructions: In performance footwear, it is common to combine multiple foam layers to balance comfort and durability. A typical hybrid structure may include a cushioning layer (such as EVA or PU) paired with a firmer structural base (such as rebonded foam).
This layered approach allows manufacturers to manage shock absorption while maintaining long-term stability, making it suitable for premium athletic footwear, occupational shoes, and medical or orthopedic designs.

Different footwear categories place different demands on midsole and soling foams. Athletic shoes typically prioritize lightweight cushioning and energy return, while safety and industrial footwear require higher density materials to manage load and protect the wearer. Leather and formal shoes often use firmer foams to maintain shape and appearance, whereas hiking and work boots require materials that can withstand uneven terrain and prolonged use.
User Profile Considerations: User characteristics also influence foam selection. Footwear designed for adult men or overweight users generally requires higher density foams to prevent early compression. Women’s footwear often balances reduced weight with moderate support, while children’s footwear favors lighter materials that allow natural foot movement. In medical and orthopedic applications, stability and alignment are prioritized over softness, often requiring firmer base layers combined with controlled cushioning.
Medical Footwear Applications: In medical footwear, the midsole plays a role in supporting posture, reducing excessive impact, and maintaining consistent performance over long wear periods. Materials selected for these applications must resist deformation and provide predictable mechanical behavior. Rebonded and high-resilience foams are commonly used as structural layers, sometimes combined with softer materials for controlled cushioning.

Soling and midsole foams are critical to footwear performance, durability, and user safety. The selection of foam type, density, thickness, and construction method directly affects how a shoe performs under real-world conditions. Understanding these materials allows manufacturers to design footwear that meets functional requirements across athletic, industrial, casual, and medical categories.