Shoe insoles are predominantly manufactured from expanded foam sheets – usually polyurethane, or PU for short. Unfortunately, these thermally deformed materials have only very limited resistance to water, heat, light, and sweat. Due to the conditions inside the shoe, such as a warm, humid climate and mechanical stress, the increasing abrasion of the foam material is unavoidable. Furthermore, these insole materials age rapidly and lose their mechanical resistance after only a few weeks.
The biodegradable GUPPYFRIEND insoles consist of a natural latex foam core and 100% natural fiber felts with particularly high strength. During the production process, a linen-cotton textile cover is applied to the felt made of cotton, kenaf, and hemp fibers using corn starch. Thanks to this breathable construction and the naturally antibacterial materials, the GUPPYFRIEND insoles ensure a pleasantly dry shoe climate and also have an odor-reducing effect.
The GUPPYFRIEND insole can be universally adapted to the shape of your shoes by trimming it to size. It is suitable not only for everyday shoes, but also for barefoot shoes and all types of sports shoes, such as hiking, soccer, running, and cycling shoes.
The GUPPYFRIEND insoles adapt to the shoe and provide light arch support.
Polyurethane ages. As soon as PU comes into contact with water or moisture, a chemical process called "hydrolysis" begins. In simple terms, it can be described as the cleavage of chemical bonds through reaction with water. The water (H2O) atoms split the PU polymer chains from the surface inward. Chemical additives can slow down this reaction. Nevertheless, the health concerns associated with these materials remain.
The chemicals used in the production of PU foam boards, polyol and isocyanate, are extremely hazardous to the environment and human health. Transport, processing, and disposal can pose unpredictable risks.
Furthermore, the approval of the chemicals polyol and isocyanate requires numerous, long-lasting, and cruel tests on mammals. We do not wish to be complicit in these often-unmentioned "side effects."
Insoles continue to lose microplastics or can end up in the environment if they are not disposed of properly. Normally, they must be put in the residual waste because they are reliably incinerated there.
However, we cannot say for sure: it is often not transparent which chemicals are actually used in the soles. It is possible that they are actually better off in hazardous waste.
