Why do Shoe Soles Disintegrate?

There is no doubt that some of you have shoes of the same age in your closet, but they are still very good to wear. The reason is the aforementioned polyurethane (PU) sole material.

Polyurethane (PU) is often used in safety shoes because of its many positive properties.

very light
Very flexible
Very good shock absorption performance
Highly wear-resistant
Good anti-slip performance
All of these have a very beneficial effect on the wearer's natural movement patterns and the product life (mechanical influence) of the sole.

The specific composition of PU produces these material qualities, but it also affects the service life of the material.

The most important thing is that the PU sole material undergoes a natural aging process-hydrolysis.

What happens to the aging of the sole?
PU is composed of long polymer chains, which gradually separate due to the influence of moisture. Therefore, PU will lose its flexibility and become brittle over time.

As the shoe ages, this can cause signs of decomposition of the sole.

But why storing shoes is often more detrimental to their longevity than wear?

Work shoes are usually stored in basements, sheds or garages-usually places with high moisture. It is this moisture that amplifies the hydrolysis process and makes the shoes age faster, even if they are not actually worn.

Other sole materials will also undergo an aging process. For example, the plasticizer contained in rubber gradually diffuses out of the material. This will also cause the sole to lose elasticity and become hard and brittle.

Ethylene vinyl acetate (EVA), which is well known in the sports footwear industry, does not hydrolyze, but it does have a disadvantage: it shrinks faster under constant loads such as walking and running, so it does not return to its original shape.

This is easy to recognize from the small "wrinkles" obtained in the material.

Our recommendations for you and your safety shoes
The aging of safety shoes is a completely normal process that all shoes go through. If we want to benefit from all the positive characteristics of safety shoes, we need to realize that the product life of shoes is limited.

We recommend changing safety shoes regularly. Due to other effects that also affect the use and storage period, the shoes will not be used indefinitely. More information can be found in the instructions that accompany each pair of shoes.