Choosing Foams for Cold-Weather Footwear
With winter fast approaching, it’s time to start thinking about how your footwear will behave in the colder weather. If you’ve ever left the house in your favorite pair of trainers only to find they feel completely different below certain temperatures, you aren’t going crazy. The foam used for your insoles and midsoles can be impacted by extreme conditions and may perform differently as a result. So, a foam that is otherwise high quality may not suit the needs of winter footwear based on its material and structural properties. Here is what you can expect for how your shoe foam may function if not properly outfitted for winter—and foams that may work instead.
How Extreme Cold Affects Foam Mechanical Properties
There are many different types of foam used in footwear, and temperature will affect each one differently because of the varied base materials and structures. Therefore, some foams will be more reactive than others. That said, there are certain trends in how extreme cold will affect a foam’s mechanical properties.
Increased Firmness
Footwear foams can harden in cold temperatures, becoming firmer underfoot. A foam that is more sensitive to cold weather can suddenly feel less cushioned and overall less comfortable. If you’re counting on your footwear for cushioning and comfort for training or all day wear, it’s definitely important to consider if the foam is appropriate for the winter months.
More Rigidity
Freezing temperatures can cause foam to stiffen, limiting its flexibility and dynamic movement. The foam may also feel more brittle. If your shoe includes carbon fiber plates they will already have a degree of stiffness accounted for in the design, but with unexpected stiffness in the midsoles, running or walking may not feel as smooth as you’re used to.
Reduced Energy Returns
Because extreme cold impacts how the material’s cells and structure function, the foam may suffer from reduced recovery after compression and the foam may not provide that bounce back that’s so great for energy return.
Impacted Durability
Exposure to extreme temperatures will wear the foam down quicker than otherwise anticipated. So, especially with foams more susceptible to performance drops in cold weather, you may find that you need to replace them sooner even if your usage has been minimal.
Read More: All About Footwear Foam Physical Properties
Cold-Resilient Foam Alternatives
Not every foam is impacted by cold temperatures to the same degree. Unfortunately, EVA, a typically durable closed cell foam found in most running shoes, is highly sensitive to the cold weather. If the properties listed above aren’t what you are looking for in your footwear, here are other foams to consider:
● Polyamide Block Elastomer (PEBA): A very lightweight and bouncy closed cell foam often used in racing shoes. PEBA is less reactive to the cold than EVA but does become stiffer than TPU and TPE variations.
● Thermoplastic Elastomers (TPE) and Thermoplastic Polyurethane (TPU): Made from thermoplastic filaments, these closed cell foams are highly durable and provide excellent energy return. Cold does affect these foams and their various subtypes (ETPU, ATPU), but to a much lesser degree. TPE and TPU foams also retain the ability to recover from compression.
Through our Pulsion line of foams, we offer Pulsion® Ignite ETPU, a high rebound ETPU foam for insoles and midsoles that provides active comfort for a range of footwear categories.
Materials Engineered for Active Comfort
INSITE Pulsion ETPU foam provides explosive momentum and energy return to elevate athletic performance. Request your sample today to experience how INSITE footwear foams can take your footwear to the next level.